diff --git a/ChangeLog b/ChangeLog
index 3673f5d..23be7dd 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -6,11 +6,11 @@
    * Fix potential heap buffer overread and overwrite in DTLS if
      MBEDTLS_SSL_DTLS_CONNECTION_ID is enabled and
      MBEDTLS_SSL_CID_IN_LEN_MAX > 2 * MBEDTLS_SSL_CID_OUT_LEN_MAX.
-   * An adversary with access to precise enough information about memory
-     accesses (typically, an untrusted operating system attacking a secure
-     enclave) could recover an RSA private key after observing the victim
-     performing a single private-key operation if the window size used for the
-     exponentiation was 3 or smaller. Found and reported by Zili KOU,
+   * Fix an issue where an adversary with access to precise enough information
+     about memory accesses (typically, an untrusted operating system attacking
+     a secure enclave) could recover an RSA private key after observing the
+     victim performing a single private-key operation if the window size used
+     for the exponentiation was 3 or smaller. Found and reported by Zili KOU,
      Wenjian HE, Sharad Sinha, and Wei ZHANG. See "Cache Side-channel Attacks
      and Defenses of the Sliding Window Algorithm in TEEs" - Design, Automation
      and Test in Europe 2023.
@@ -337,16 +337,17 @@
    * It was possible to configure MBEDTLS_ECP_MAX_BITS to a value that is
      too small, leading to buffer overflows in ECC operations. Fail the build
      in such a case.
-   * An adversary with access to precise enough information about memory
-     accesses (typically, an untrusted operating system attacking a secure
-     enclave) could recover an RSA private key after observing the victim
-     performing a single private-key operation. Found and reported by
+   * Fix an issue where an adversary with access to precise enough information
+     about memory accesses (typically, an untrusted operating system attacking
+     a secure enclave) could recover an RSA private key after observing the
+     victim performing a single private-key operation. Found and reported by
      Zili KOU, Wenjian HE, Sharad Sinha, and Wei ZHANG.
-   * An adversary with access to precise enough timing information (typically, a
-     co-located process) could recover a Curve25519 or Curve448 static ECDH key
-     after inputting a chosen public key and observing the victim performing the
-     corresponding private-key operation. Found and reported by Leila Batina,
-     Lukas Chmielewski, Björn Haase, Niels Samwel and Peter Schwabe.
+   * Fix an issue where an adversary with access to precise enough timing
+     information (typically, a co-located process) could recover a Curve25519
+     or Curve448 static ECDH key after inputting a chosen public key and
+     observing the victim performing the corresponding private-key operation.
+     Found and reported by Leila Batina, Lukas Chmielewski, Björn Haase, Niels
+     Samwel and Peter Schwabe.
 
 Bugfix
    * Add printf function attributes to mbedtls_debug_print_msg to ensure we
diff --git a/ChangeLog.d/mbedtls_ssl_read_undefined_behavior.txt b/ChangeLog.d/mbedtls_ssl_read_undefined_behavior.txt
new file mode 100644
index 0000000..1f2c563
--- /dev/null
+++ b/ChangeLog.d/mbedtls_ssl_read_undefined_behavior.txt
@@ -0,0 +1,3 @@
+Bugfix
+   * Fix undefined behavior in mbedtls_ssl_read() and mbedtls_ssl_write() if
+     len argument is 0 and buffer is NULL.
diff --git a/docs/getting_started.md b/docs/getting_started.md
deleted file mode 100644
index 507afa1..0000000
--- a/docs/getting_started.md
+++ /dev/null
@@ -1,962 +0,0 @@
-## Getting started with Mbed TLS
-
-### What is Mbed TLS?
-
-Mbed TLS is an open source cryptographic library that supports a wide range of
-cryptographic operations, including:
-* Key management
-* Hashing
-* Symmetric cryptography
-* Asymmetric cryptography
-* Message authentication (MAC)
-* Key generation and derivation
-* Authenticated encryption with associated data (AEAD)
-
-Mbed TLS provides a reference implementation of the cryptography interface of
-the Arm Platform Security Architecture (PSA). It is written in portable C.
-
-Mbed TLS is distributed under the Apache License, version 2.0.
-
-#### Platform Security Architecture (PSA)
-
-Arm's Platform Security Architecture (PSA) is a holistic set of threat models,
-security analyses, hardware and firmware architecture specifications, and an
-open source firmware reference implementation. PSA provides a recipe, based on
-industry best practice, that enables you to design security into both hardware
-and firmware consistently. Part of the API provided by PSA is the cryptography
-interface, which provides access to a set of primitives.
-
-### Using Mbed TLS
-
-* [Getting the Mbed TLS library](#getting-the-mbed-tls-library)
-* [Building the Mbed TLS library](#building-the-mbed-tls-library)
-* [Using the PSA Crypto API](#using-the-psa-crypto-api)
-* [Importing a key](#importing-a-key)
-* [Signing a message using RSA](#signing-a-message-using-RSA)
-* [Encrypting or decrypting using symmetric ciphers](#encrypting-or-decrypting-using-symmetric-ciphers)
-* [Hashing a message](#hashing-a-message)
-* [Deriving a new key from an existing key](#deriving-a-new-key-from-an-existing-key)
-* [Generating a random value](#generating-a-random-value)
-* [Authenticating and encrypting or decrypting a message](#authenticating-and-encrypting-or-decrypting-a-message)
-* [Generating and exporting keys](#generating-and-exporting-keys)
-* [More about the PSA Crypto API](#more-about-the-psa-crypto-api)
-
-### Getting the Mbed TLS library
-
-Mbed TLS releases are available in the [public GitHub repository](https://github.com/Mbed-TLS/mbedtls).
-
-### Building the Mbed TLS library
-
-**Prerequisites to building the library with the provided makefiles:**
-* GNU Make.
-* A C toolchain (compiler, linker, archiver) that supports C99.
-* Python 3.6 to generate the test code.
-* Perl to run the tests.
-
-If you have a C compiler such as GCC or Clang, just run `make` in the top-level
-directory to build the library, a set of unit tests and some sample programs.
-
-To select a different compiler, set the `CC` variable to the name or path of the
-compiler and linker (default: `cc`) and set `AR` to a compatible archiver
-(default: `ar`); for example:
-```
-make CC=arm-linux-gnueabi-gcc AR=arm-linux-gnueabi-ar
-```
-The provided makefiles pass options to the compiler that assume a GCC-like
-command line syntax. To use a different compiler, you may need to pass different
-values for `CFLAGS`, `WARNINGS_CFLAGS` and `LDFLAGS`.
-
-To run the unit tests on the host machine, run `make test` from the top-level
-directory. If you are cross-compiling, copy the test executable from the `tests`
-directory to the target machine.
-
-### Using the PSA Crypto API
-
-If using PSA Crypto, you must initialize the library by calling
-`psa_crypto_init()` before any other PSA API.
-
-### Importing a key
-
-To use a key for cryptography operations in PSA, you need to first
-import it. The import operation returns the identifier of the key for use
-with other function calls.
-
-**Prerequisites to importing keys:**
-* Initialize the library with a successful call to `psa_crypto_init()`.
-
-This example shows how to import a key:
-```C
-void import_a_key(const uint8_t *key, size_t key_len)
-{
-    psa_status_t status;
-    psa_key_attributes_t attributes = PSA_KEY_ATTRIBUTES_INIT;
-    psa_key_id_t key_id;
-
-    printf("Import an AES key...\t");
-    fflush(stdout);
-
-    /* Initialize PSA Crypto */
-    status = psa_crypto_init();
-    if (status != PSA_SUCCESS) {
-        printf("Failed to initialize PSA Crypto\n");
-        return;
-    }
-
-    /* Set key attributes */
-    psa_set_key_usage_flags(&attributes, 0);
-    psa_set_key_algorithm(&attributes, 0);
-    psa_set_key_type(&attributes, PSA_KEY_TYPE_AES);
-    psa_set_key_bits(&attributes, 128);
-
-    /* Import the key */
-    status = psa_import_key(&attributes, key, key_len, &key_id);
-    if (status != PSA_SUCCESS) {
-        printf("Failed to import key\n");
-        return;
-    }
-    printf("Imported a key\n");
-
-    /* Free the attributes */
-    psa_reset_key_attributes(&attributes);
-
-    /* Destroy the key */
-    psa_destroy_key(key_id);
-
-    mbedtls_psa_crypto_free();
-}
-```
-
-### Signing a message using RSA
-
-The PSA Crypto API supports encrypting, decrypting, signing and verifying
-messages using public key signature algorithms, such as RSA or ECDSA.
-
-**Prerequisites to performing asymmetric signature operations:**
-* Initialize the library with a successful call to `psa_crypto_init()`.
-* Have a valid key with appropriate attributes set:
-    * Usage flag `PSA_KEY_USAGE_SIGN_HASH` to allow signing.
-    * Usage flag `PSA_KEY_USAGE_VERIFY_HASH` to allow signature verification.
-    * Algorithm set to the desired signature algorithm.
-
-This example shows how to sign a hash that has already been calculated:
-```C
-void sign_a_message_using_rsa(const uint8_t *key, size_t key_len)
-{
-    psa_status_t status;
-    psa_key_attributes_t attributes = PSA_KEY_ATTRIBUTES_INIT;
-    uint8_t hash[32] = {0x50, 0xd8, 0x58, 0xe0, 0x98, 0x5e, 0xcc, 0x7f,
-                        0x60, 0x41, 0x8a, 0xaf, 0x0c, 0xc5, 0xab, 0x58,
-                        0x7f, 0x42, 0xc2, 0x57, 0x0a, 0x88, 0x40, 0x95,
-                        0xa9, 0xe8, 0xcc, 0xac, 0xd0, 0xf6, 0x54, 0x5c};
-    uint8_t signature[PSA_SIGNATURE_MAX_SIZE] = {0};
-    size_t signature_length;
-    psa_key_id_t key_id;
-
-    printf("Sign a message...\t");
-    fflush(stdout);
-
-    /* Initialize PSA Crypto */
-    status = psa_crypto_init();
-    if (status != PSA_SUCCESS) {
-        printf("Failed to initialize PSA Crypto\n");
-        return;
-    }
-
-    /* Set key attributes */
-    psa_set_key_usage_flags(&attributes, PSA_KEY_USAGE_SIGN_HASH);
-    psa_set_key_algorithm(&attributes, PSA_ALG_RSA_PKCS1V15_SIGN_RAW);
-    psa_set_key_type(&attributes, PSA_KEY_TYPE_RSA_KEY_PAIR);
-    psa_set_key_bits(&attributes, 1024);
-
-    /* Import the key */
-    status = psa_import_key(&attributes, key, key_len, &key_id);
-    if (status != PSA_SUCCESS) {
-        printf("Failed to import key\n");
-        return;
-    }
-
-    /* Sign message using the key */
-    status = psa_sign_hash(key_id, PSA_ALG_RSA_PKCS1V15_SIGN_RAW,
-                           hash, sizeof(hash),
-                           signature, sizeof(signature),
-                           &signature_length);
-    if (status != PSA_SUCCESS) {
-        printf("Failed to sign\n");
-        return;
-    }
-
-    printf("Signed a message\n");
-
-    /* Free the attributes */
-    psa_reset_key_attributes(&attributes);
-
-    /* Destroy the key */
-    psa_destroy_key(key_id);
-
-    mbedtls_psa_crypto_free();
-}
-```
-
-### Using symmetric ciphers
-
-The PSA Crypto API supports encrypting and decrypting messages using various
-symmetric cipher algorithms (both block and stream ciphers).
-
-**Prerequisites to working with the symmetric cipher API:**
-* Initialize the library with a successful call to `psa_crypto_init()`.
-* Have a symmetric key. This key's usage flags must include
-  `PSA_KEY_USAGE_ENCRYPT` to allow encryption or `PSA_KEY_USAGE_DECRYPT` to
-  allow decryption.
-
-**To encrypt a message with a symmetric cipher:**
-1. Allocate an operation (`psa_cipher_operation_t`) structure to pass to the
-   cipher functions.
-1. Initialize the operation structure to zero or to `PSA_CIPHER_OPERATION_INIT`.
-1. Call `psa_cipher_encrypt_setup()` to specify the algorithm and the key to be
-   used.
-1. Call either `psa_cipher_generate_iv()` or `psa_cipher_set_iv()` to generate
-   or set the initialization vector (IV). We recommend calling
-   `psa_cipher_generate_iv()`, unless you require a specific IV value.
-1. Call `psa_cipher_update()` with the message to encrypt. You may call this
-   function multiple times, passing successive fragments of the message on
-   successive calls.
-1. Call `psa_cipher_finish()` to end the operation and output the encrypted
-   message.
-
-This example shows how to encrypt data using an AES (Advanced Encryption
-Standard) key in CBC (Cipher Block Chaining) mode with no padding (assuming all
-prerequisites have been fulfilled):
-```c
-void encrypt_with_symmetric_ciphers(const uint8_t *key, size_t key_len)
-{
-    enum {
-        block_size = PSA_BLOCK_CIPHER_BLOCK_LENGTH(PSA_KEY_TYPE_AES),
-    };
-    psa_status_t status;
-    psa_key_attributes_t attributes = PSA_KEY_ATTRIBUTES_INIT;
-    psa_algorithm_t alg = PSA_ALG_CBC_NO_PADDING;
-    uint8_t plaintext[block_size] = SOME_PLAINTEXT;
-    uint8_t iv[block_size];
-    size_t iv_len;
-    uint8_t output[block_size];
-    size_t output_len;
-    psa_key_id_t key_id;
-    psa_cipher_operation_t operation = PSA_CIPHER_OPERATION_INIT;
-
-    printf("Encrypt with cipher...\t");
-    fflush(stdout);
-
-    /* Initialize PSA Crypto */
-    status = psa_crypto_init();
-    if (status != PSA_SUCCESS)
-    {
-        printf("Failed to initialize PSA Crypto\n");
-        return;
-    }
-
-    /* Import a key */
-    psa_set_key_usage_flags(&attributes, PSA_KEY_USAGE_ENCRYPT);
-    psa_set_key_algorithm(&attributes, alg);
-    psa_set_key_type(&attributes, PSA_KEY_TYPE_AES);
-    psa_set_key_bits(&attributes, 128);
-    status = psa_import_key(&attributes, key, key_len, &key_id);
-    if (status != PSA_SUCCESS) {
-        printf("Failed to import a key\n");
-        return;
-    }
-    psa_reset_key_attributes(&attributes);
-
-    /* Encrypt the plaintext */
-    status = psa_cipher_encrypt_setup(&operation, key_id, alg);
-    if (status != PSA_SUCCESS) {
-        printf("Failed to begin cipher operation\n");
-        return;
-    }
-    status = psa_cipher_generate_iv(&operation, iv, sizeof(iv), &iv_len);
-    if (status != PSA_SUCCESS) {
-        printf("Failed to generate IV\n");
-        return;
-    }
-    status = psa_cipher_update(&operation, plaintext, sizeof(plaintext),
-                               output, sizeof(output), &output_len);
-    if (status != PSA_SUCCESS) {
-        printf("Failed to update cipher operation\n");
-        return;
-    }
-    status = psa_cipher_finish(&operation, output + output_len,
-                               sizeof(output) - output_len, &output_len);
-    if (status != PSA_SUCCESS) {
-        printf("Failed to finish cipher operation\n");
-        return;
-    }
-    printf("Encrypted plaintext\n");
-
-    /* Clean up cipher operation context */
-    psa_cipher_abort(&operation);
-
-    /* Destroy the key */
-    psa_destroy_key(key_id);
-
-    mbedtls_psa_crypto_free();
-}
-```
-
-**To decrypt a message with a symmetric cipher:**
-1. Allocate an operation (`psa_cipher_operation_t`) structure to pass to the
-   cipher functions.
-1. Initialize the operation structure to zero or to `PSA_CIPHER_OPERATION_INIT`.
-1. Call `psa_cipher_decrypt_setup()` to specify the algorithm and the key to be
-   used.
-1. Call `psa_cipher_set_iv()` with the IV for the decryption.
-1. Call `psa_cipher_update()` with the message to encrypt. You may call this
-   function multiple times, passing successive fragments of the message on
-   successive calls.
-1. Call `psa_cipher_finish()` to end the operation and output the decrypted
-   message.
-
-This example shows how to decrypt encrypted data using an AES key in CBC mode
-with no padding (assuming all prerequisites have been fulfilled):
-```c
-void decrypt_with_symmetric_ciphers(const uint8_t *key, size_t key_len)
-{
-    enum {
-        block_size = PSA_BLOCK_CIPHER_BLOCK_LENGTH(PSA_KEY_TYPE_AES),
-    };
-    psa_status_t status;
-    psa_key_attributes_t attributes = PSA_KEY_ATTRIBUTES_INIT;
-    psa_algorithm_t alg = PSA_ALG_CBC_NO_PADDING;
-    psa_cipher_operation_t operation = PSA_CIPHER_OPERATION_INIT;
-    uint8_t ciphertext[block_size] = SOME_CIPHERTEXT;
-    uint8_t iv[block_size] = ENCRYPTED_WITH_IV;
-    uint8_t output[block_size];
-    size_t output_len;
-    psa_key_id_t key_id;
-
-    printf("Decrypt with cipher...\t");
-    fflush(stdout);
-
-    /* Initialize PSA Crypto */
-    status = psa_crypto_init();
-    if (status != PSA_SUCCESS)
-    {
-        printf("Failed to initialize PSA Crypto\n");
-        return;
-    }
-
-    /* Import a key */
-    psa_set_key_usage_flags(&attributes, PSA_KEY_USAGE_DECRYPT);
-    psa_set_key_algorithm(&attributes, alg);
-    psa_set_key_type(&attributes, PSA_KEY_TYPE_AES);
-    psa_set_key_bits(&attributes, 128);
-    status = psa_import_key(&attributes, key, key_len, &key_id);
-    if (status != PSA_SUCCESS) {
-        printf("Failed to import a key\n");
-        return;
-    }
-    psa_reset_key_attributes(&attributes);
-
-    /* Decrypt the ciphertext */
-    status = psa_cipher_decrypt_setup(&operation, key_id, alg);
-    if (status != PSA_SUCCESS) {
-        printf("Failed to begin cipher operation\n");
-        return;
-    }
-    status = psa_cipher_set_iv(&operation, iv, sizeof(iv));
-    if (status != PSA_SUCCESS) {
-        printf("Failed to set IV\n");
-        return;
-    }
-    status = psa_cipher_update(&operation, ciphertext, sizeof(ciphertext),
-                               output, sizeof(output), &output_len);
-    if (status != PSA_SUCCESS) {
-        printf("Failed to update cipher operation\n");
-        return;
-    }
-    status = psa_cipher_finish(&operation, output + output_len,
-                               sizeof(output) - output_len, &output_len);
-    if (status != PSA_SUCCESS) {
-        printf("Failed to finish cipher operation\n");
-        return;
-    }
-    printf("Decrypted ciphertext\n");
-
-    /* Clean up cipher operation context */
-    psa_cipher_abort(&operation);
-
-    /* Destroy the key */
-    psa_destroy_key(key_id);
-
-    mbedtls_psa_crypto_free();
-}
-```
-
-#### Handling cipher operation contexts
-
-After you've initialized the operation structure with a successful call to
-`psa_cipher_encrypt_setup()` or `psa_cipher_decrypt_setup()`, you can terminate
-the operation at any time by calling `psa_cipher_abort()`.
-
-The call to `psa_cipher_abort()` frees any resources associated with the
-operation, except for the operation structure itself.
-
-The PSA Crypto API implicitly calls `psa_cipher_abort()` when:
-* A call to `psa_cipher_generate_iv()`, `psa_cipher_set_iv()` or
-  `psa_cipher_update()` fails (returning any status other than `PSA_SUCCESS`).
-* A call to `psa_cipher_finish()` succeeds or fails.
-
-After an implicit or explicit call to `psa_cipher_abort()`, the operation
-structure is invalidated; in other words, you cannot reuse the operation
-structure for the same operation. You can, however, reuse the operation
-structure for a different operation by calling either
-`psa_cipher_encrypt_setup()` or `psa_cipher_decrypt_setup()` again.
-
-You must call `psa_cipher_abort()` at some point for any operation that is
-initialized successfully (by a successful call to `psa_cipher_encrypt_setup()`
-or `psa_cipher_decrypt_setup()`).
-
-Making multiple sequential calls to `psa_cipher_abort()` on an operation that
-is terminated (either implicitly or explicitly) is safe and has no effect.
-
-### Hashing a message
-
-The PSA Crypto API lets you compute and verify hashes using various hashing
-algorithms.
-
-**Prerequisites to working with the hash APIs:**
-* Initialize the library with a successful call to `psa_crypto_init()`.
-
-**To calculate a hash:**
-1. Allocate an operation structure (`psa_hash_operation_t`) to pass to the hash
-   functions.
-1. Initialize the operation structure to zero or to `PSA_HASH_OPERATION_INIT`.
-1. Call `psa_hash_setup()` to specify the hash algorithm.
-1. Call `psa_hash_update()` with the message to encrypt. You may call this
-   function multiple times, passing successive fragments of the message on
-   successive calls.
-1. Call `psa_hash_finish()` to calculate the hash, or `psa_hash_verify()` to
-   compare the computed hash with an expected hash value.
-
-This example shows how to calculate the SHA-256 hash of a message:
-```c
-    psa_status_t status;
-    psa_algorithm_t alg = PSA_ALG_SHA_256;
-    psa_hash_operation_t operation = PSA_HASH_OPERATION_INIT;
-    unsigned char input[] = { 'a', 'b', 'c' };
-    unsigned char actual_hash[PSA_HASH_MAX_SIZE];
-    size_t actual_hash_len;
-
-    printf("Hash a message...\t");
-    fflush(stdout);
-
-    /* Initialize PSA Crypto */
-    status = psa_crypto_init();
-    if (status != PSA_SUCCESS) {
-        printf("Failed to initialize PSA Crypto\n");
-        return;
-    }
-
-    /* Compute hash of message  */
-    status = psa_hash_setup(&operation, alg);
-    if (status != PSA_SUCCESS) {
-        printf("Failed to begin hash operation\n");
-        return;
-    }
-    status = psa_hash_update(&operation, input, sizeof(input));
-    if (status != PSA_SUCCESS) {
-        printf("Failed to update hash operation\n");
-        return;
-    }
-    status = psa_hash_finish(&operation, actual_hash, sizeof(actual_hash),
-                             &actual_hash_len);
-    if (status != PSA_SUCCESS) {
-        printf("Failed to finish hash operation\n");
-        return;
-    }
-
-    printf("Hashed a message\n");
-
-    /* Clean up hash operation context */
-    psa_hash_abort(&operation);
-
-    mbedtls_psa_crypto_free();
-```
-
-This example shows how to verify the SHA-256 hash of a message:
-```c
-    psa_status_t status;
-    psa_algorithm_t alg = PSA_ALG_SHA_256;
-    psa_hash_operation_t operation = PSA_HASH_OPERATION_INIT;
-    unsigned char input[] = { 'a', 'b', 'c' };
-    unsigned char expected_hash[] = {
-        0xba, 0x78, 0x16, 0xbf, 0x8f, 0x01, 0xcf, 0xea, 0x41, 0x41, 0x40, 0xde,
-        0x5d, 0xae, 0x22, 0x23, 0xb0, 0x03, 0x61, 0xa3, 0x96, 0x17, 0x7a, 0x9c,
-        0xb4, 0x10, 0xff, 0x61, 0xf2, 0x00, 0x15, 0xad
-    };
-    size_t expected_hash_len = PSA_HASH_LENGTH(alg);
-
-    printf("Verify a hash...\t");
-    fflush(stdout);
-
-    /* Initialize PSA Crypto */
-    status = psa_crypto_init();
-    if (status != PSA_SUCCESS) {
-        printf("Failed to initialize PSA Crypto\n");
-        return;
-    }
-
-    /* Verify message hash */
-    status = psa_hash_setup(&operation, alg);
-    if (status != PSA_SUCCESS) {
-        printf("Failed to begin hash operation\n");
-        return;
-    }
-    status = psa_hash_update(&operation, input, sizeof(input));
-    if (status != PSA_SUCCESS) {
-        printf("Failed to update hash operation\n");
-        return;
-    }
-    status = psa_hash_verify(&operation, expected_hash, expected_hash_len);
-    if (status != PSA_SUCCESS) {
-        printf("Failed to verify hash\n");
-        return;
-    }
-
-    printf("Verified a hash\n");
-
-    /* Clean up hash operation context */
-    psa_hash_abort(&operation);
-
-    mbedtls_psa_crypto_free();
-```
-
-The API provides the macro `PSA_HASH_LENGTH`, which returns the expected hash
-length (in bytes) for the specified algorithm.
-
-#### Handling hash operation contexts
-
-After a successful call to `psa_hash_setup()`, you can terminate the operation
-at any time by calling `psa_hash_abort()`. The call to `psa_hash_abort()` frees
-any resources associated with the operation, except for the operation structure
-itself.
-
-The PSA Crypto API implicitly calls `psa_hash_abort()` when:
-1. A call to `psa_hash_update()` fails (returning any status other than
-   `PSA_SUCCESS`).
-1. A call to `psa_hash_finish()` succeeds or fails.
-1. A call to `psa_hash_verify()` succeeds or fails.
-
-After an implicit or explicit call to `psa_hash_abort()`, the operation
-structure is invalidated; in other words, you cannot reuse the operation
-structure for the same operation. You can, however, reuse the operation
-structure for a different operation by calling `psa_hash_setup()` again.
-
-You must call `psa_hash_abort()` at some point for any operation that is
-initialized successfully (by a successful call to `psa_hash_setup()`) .
-
-Making multiple sequential calls to `psa_hash_abort()` on an operation that has
-already been terminated (either implicitly or explicitly) is safe and has no
-effect.
-
-### Generating a random value
-
-The PSA Crypto API can generate random data.
-
-**Prerequisites to generating random data:**
-* Initialize the library with a successful call to `psa_crypto_init()`.
-
-<span class="notes">**Note:** To generate a random key, use `psa_generate_key()`
-instead of `psa_generate_random()`.</span>
-
-This example shows how to generate ten bytes of random data by calling
-`psa_generate_random()`:
-```C
-    psa_status_t status;
-    uint8_t random[10] = { 0 };
-
-    printf("Generate random...\t");
-    fflush(stdout);
-
-    /* Initialize PSA Crypto */
-    status = psa_crypto_init();
-    if (status != PSA_SUCCESS) {
-        printf("Failed to initialize PSA Crypto\n");
-        return;
-    }
-
-    status = psa_generate_random(random, sizeof(random));
-    if (status != PSA_SUCCESS) {
-        printf("Failed to generate a random value\n");
-        return;
-    }
-
-    printf("Generated random data\n");
-
-    /* Clean up */
-    mbedtls_psa_crypto_free();
-```
-
-### Deriving a new key from an existing key
-
-The PSA Crypto API provides a key derivation API that lets you derive new keys
-from existing ones. The key derivation API has functions to take inputs,
-including other keys and data, and functions to generate outputs, such as
-new keys or other data.
-
-You must first initialize and set up a key derivation context,
-provided with a key and, optionally, other data. Then, use the key derivation
-context to either read derived data to a buffer or send derived data directly
-to a key slot.
-
-See the documentation for the particular algorithm (such as HKDF or the
-TLS 1.2 PRF) for information about which inputs to pass when, and when you can
-obtain which outputs.
-
-**Prerequisites to working with the key derivation APIs:**
-* Initialize the library with a successful call to `psa_crypto_init()`.
-* Use a key with the appropriate attributes set:
-    * Usage flags set for key derivation (`PSA_KEY_USAGE_DERIVE`)
-    * Key type set to `PSA_KEY_TYPE_DERIVE`.
-    * Algorithm set to a key derivation algorithm
-      (for example, `PSA_ALG_HKDF(PSA_ALG_SHA_256)`).
-
-**To derive a new AES-CTR 128-bit encryption key into a given key slot using HKDF
-with a given key, salt and info:**
-
-1. Set up the key derivation context using the `psa_key_derivation_setup()`
-function, specifying the derivation algorithm `PSA_ALG_HKDF(PSA_ALG_SHA_256)`.
-1. Provide an optional salt with `psa_key_derivation_input_bytes()`.
-1. Provide info with `psa_key_derivation_input_bytes()`.
-1. Provide a secret with `psa_key_derivation_input_key()`, referencing a key
-   that can be used for key derivation.
-1. Set the key attributes desired for the new derived key. We'll set
-   the `PSA_KEY_USAGE_ENCRYPT` usage flag and the `PSA_ALG_CTR` algorithm for
-   this example.
-1. Derive the key by calling `psa_key_derivation_output_key()`.
-1. Clean up the key derivation context.
-
-At this point, the derived key slot holds a new 128-bit AES-CTR encryption key
-derived from the key, salt and info provided:
-```C
-    psa_status_t status;
-    psa_key_attributes_t attributes = PSA_KEY_ATTRIBUTES_INIT;
-    static const unsigned char key[] = {
-        0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b,
-        0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b,
-        0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b,
-        0x0b };
-    static const unsigned char salt[] = {
-        0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06,
-        0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c };
-    static const unsigned char info[] = {
-        0xf0, 0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6,
-        0xf7, 0xf8, 0xf9 };
-    psa_algorithm_t alg = PSA_ALG_HKDF(PSA_ALG_SHA_256);
-    psa_key_derivation_operation_t operation =
-        PSA_KEY_DERIVATION_OPERATION_INIT;
-    size_t derived_bits = 128;
-    size_t capacity = PSA_BITS_TO_BYTES(derived_bits);
-    psa_key_id_t base_key;
-    psa_key_id_t derived_key;
-
-    printf("Derive a key (HKDF)...\t");
-    fflush(stdout);
-
-    /* Initialize PSA Crypto */
-    status = psa_crypto_init();
-    if (status != PSA_SUCCESS) {
-        printf("Failed to initialize PSA Crypto\n");
-        return;
-    }
-
-    /* Import a key for use in key derivation. If such a key has already been
-     * generated or imported, you can skip this part. */
-    psa_set_key_usage_flags(&attributes, PSA_KEY_USAGE_DERIVE);
-    psa_set_key_algorithm(&attributes, alg);
-    psa_set_key_type(&attributes, PSA_KEY_TYPE_DERIVE);
-    status = psa_import_key(&attributes, key, sizeof(key), &base_key);
-    if (status != PSA_SUCCESS) {
-        printf("Failed to import a key\n");
-        return;
-    }
-    psa_reset_key_attributes(&attributes);
-
-    /* Derive a key */
-    status = psa_key_derivation_setup(&operation, alg);
-    if (status != PSA_SUCCESS) {
-        printf("Failed to begin key derivation\n");
-        return;
-    }
-    status = psa_key_derivation_set_capacity(&operation, capacity);
-    if (status != PSA_SUCCESS) {
-        printf("Failed to set capacity\n");
-        return;
-    }
-    status = psa_key_derivation_input_bytes(&operation,
-                                            PSA_KEY_DERIVATION_INPUT_SALT,
-                                            salt, sizeof(salt));
-    if (status != PSA_SUCCESS) {
-        printf("Failed to input salt (extract)\n");
-        return;
-    }
-    status = psa_key_derivation_input_key(&operation,
-                                          PSA_KEY_DERIVATION_INPUT_SECRET,
-                                          base_key);
-    if (status != PSA_SUCCESS) {
-        printf("Failed to input key (extract)\n");
-        return;
-    }
-    status = psa_key_derivation_input_bytes(&operation,
-                                            PSA_KEY_DERIVATION_INPUT_INFO,
-                                            info, sizeof(info));
-    if (status != PSA_SUCCESS) {
-        printf("Failed to input info (expand)\n");
-        return;
-    }
-    psa_set_key_usage_flags(&attributes, PSA_KEY_USAGE_ENCRYPT);
-    psa_set_key_algorithm(&attributes, PSA_ALG_CTR);
-    psa_set_key_type(&attributes, PSA_KEY_TYPE_AES);
-    psa_set_key_bits(&attributes, 128);
-    status = psa_key_derivation_output_key(&attributes, &operation,
-                                           &derived_key);
-    if (status != PSA_SUCCESS) {
-        printf("Failed to derive key\n");
-        return;
-    }
-    psa_reset_key_attributes(&attributes);
-
-    printf("Derived key\n");
-
-    /* Clean up key derivation operation */
-    psa_key_derivation_abort(&operation);
-
-    /* Destroy the keys */
-    psa_destroy_key(derived_key);
-    psa_destroy_key(base_key);
-
-    mbedtls_psa_crypto_free();
-```
-
-### Authenticating and encrypting or decrypting a message
-
-The PSA Crypto API provides a simple way to authenticate and encrypt with
-associated data (AEAD), supporting the `PSA_ALG_CCM` algorithm.
-
-**Prerequisites to working with the AEAD cipher APIs:**
-* Initialize the library with a successful call to `psa_crypto_init()`.
-* The key attributes for the key used for derivation must have the
-  `PSA_KEY_USAGE_ENCRYPT` or `PSA_KEY_USAGE_DECRYPT` usage flags.
-
-This example shows how to authenticate and encrypt a message:
-```C
-    psa_status_t status;
-    static const uint8_t key[] = {
-        0xC0, 0xC1, 0xC2, 0xC3, 0xC4, 0xC5, 0xC6, 0xC7,
-        0xC8, 0xC9, 0xCA, 0xCB, 0xCC, 0xCD, 0xCE, 0xCF };
-    static const uint8_t nonce[] = {
-        0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
-        0x08, 0x09, 0x0A, 0x0B };
-    static const uint8_t additional_data[] = {
-        0xEC, 0x46, 0xBB, 0x63, 0xB0, 0x25,
-        0x20, 0xC3, 0x3C, 0x49, 0xFD, 0x70 };
-    static const uint8_t input_data[] = {
-        0xB9, 0x6B, 0x49, 0xE2, 0x1D, 0x62, 0x17, 0x41,
-        0x63, 0x28, 0x75, 0xDB, 0x7F, 0x6C, 0x92, 0x43,
-        0xD2, 0xD7, 0xC2 };
-    uint8_t *output_data = NULL;
-    size_t output_size = 0;
-    size_t output_length = 0;
-    size_t tag_length = 16;
-    psa_key_attributes_t attributes = PSA_KEY_ATTRIBUTES_INIT;
-    psa_key_id_t key_id;
-
-    printf("Authenticate encrypt...\t");
-    fflush(stdout);
-
-    /* Initialize PSA Crypto */
-    status = psa_crypto_init();
-    if (status != PSA_SUCCESS) {
-        printf("Failed to initialize PSA Crypto\n");
-        return;
-    }
-
-    output_size = sizeof(input_data) + tag_length;
-    output_data = (uint8_t *)malloc(output_size);
-    if (!output_data) {
-        printf("Out of memory\n");
-        return;
-    }
-
-    /* Import a key */
-    psa_set_key_usage_flags(&attributes, PSA_KEY_USAGE_ENCRYPT);
-    psa_set_key_algorithm(&attributes, PSA_ALG_CCM);
-    psa_set_key_type(&attributes, PSA_KEY_TYPE_AES);
-    psa_set_key_bits(&attributes, 128);
-    status = psa_import_key(&attributes, key, sizeof(key), &key_id);
-    psa_reset_key_attributes(&attributes);
-
-    /* Authenticate and encrypt */
-    status = psa_aead_encrypt(key_id, PSA_ALG_CCM,
-                              nonce, sizeof(nonce),
-                              additional_data, sizeof(additional_data),
-                              input_data, sizeof(input_data),
-                              output_data, output_size,
-                              &output_length);
-    if (status != PSA_SUCCESS) {
-        printf("Failed to authenticate and encrypt\n");
-        return;
-    }
-
-    printf("Authenticated and encrypted\n");
-
-    /* Clean up */
-    free(output_data);
-
-    /* Destroy the key */
-    psa_destroy_key(key_id);
-
-    mbedtls_psa_crypto_free();
-```
-
-This example shows how to authenticate and decrypt a message:
-
-```C
-    psa_status_t status;
-    static const uint8_t key_data[] = {
-        0xC0, 0xC1, 0xC2, 0xC3, 0xC4, 0xC5, 0xC6, 0xC7,
-        0xC8, 0xC9, 0xCA, 0xCB, 0xCC, 0xCD, 0xCE, 0xCF };
-    static const uint8_t nonce[] = {
-        0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
-        0x08, 0x09, 0x0A, 0x0B };
-    static const uint8_t additional_data[] = {
-        0xEC, 0x46, 0xBB, 0x63, 0xB0, 0x25,
-        0x20, 0xC3, 0x3C, 0x49, 0xFD, 0x70 };
-    static const uint8_t input_data[] = {
-        0x20, 0x30, 0xE0, 0x36, 0xED, 0x09, 0xA0, 0x45, 0xAF, 0x3C, 0xBA, 0xEE,
-        0x0F, 0xC8, 0x48, 0xAF, 0xCD, 0x89, 0x54, 0xF4, 0xF6, 0x3F, 0x28, 0x9A,
-        0xA1, 0xDD, 0xB2, 0xB8, 0x09, 0xCD, 0x7C, 0xE1, 0x46, 0xE9, 0x98 };
-    uint8_t *output_data = NULL;
-    size_t output_size = 0;
-    size_t output_length = 0;
-    psa_key_attributes_t attributes = PSA_KEY_ATTRIBUTES_INIT;
-    psa_key_id_t key_id;
-
-    printf("Authenticate decrypt...\t");
-    fflush(stdout);
-
-    /* Initialize PSA Crypto */
-    status = psa_crypto_init();
-    if (status != PSA_SUCCESS) {
-        printf("Failed to initialize PSA Crypto\n");
-        return;
-    }
-
-    output_size = sizeof(input_data);
-    output_data = (uint8_t *)malloc(output_size);
-    if (!output_data) {
-        printf("Out of memory\n");
-        return;
-    }
-
-    /* Import a key */
-    psa_set_key_usage_flags(&attributes, PSA_KEY_USAGE_DECRYPT);
-    psa_set_key_algorithm(&attributes, PSA_ALG_CCM);
-    psa_set_key_type(&attributes, PSA_KEY_TYPE_AES);
-    psa_set_key_bits(&attributes, 128);
-    status = psa_import_key(&attributes, key_data, sizeof(key_data), &key_id);
-    if (status != PSA_SUCCESS) {
-        printf("Failed to import a key\n");
-        return;
-    }
-    psa_reset_key_attributes(&attributes);
-
-    /* Authenticate and decrypt */
-    status = psa_aead_decrypt(key_id, PSA_ALG_CCM,
-                              nonce, sizeof(nonce),
-                              additional_data, sizeof(additional_data),
-                              input_data, sizeof(input_data),
-                              output_data, output_size,
-                              &output_length);
-    if (status != PSA_SUCCESS) {
-        printf("Failed to authenticate and decrypt %ld\n", status);
-        return;
-    }
-
-    printf("Authenticated and decrypted\n");
-
-    /* Clean up */
-    free(output_data);
-
-    /* Destroy the key */
-    psa_destroy_key(key_id);
-
-    mbedtls_psa_crypto_free();
-```
-
-### Generating and exporting keys
-
-The PSA Crypto API provides a simple way to generate a key or key pair.
-
-**Prerequisites to using key generation and export APIs:**
-* Initialize the library with a successful call to `psa_crypto_init()`.
-
-**To generate an ECDSA key:**
-1. Set the desired key attributes for key generation by calling
-   `psa_set_key_algorithm()` with the chosen ECDSA algorithm (such as
-   `PSA_ALG_DETERMINISTIC_ECDSA(PSA_ALG_SHA_256)`). You only want to export the
-   public key, not the key pair (or private key); therefore, do not
-   set `PSA_KEY_USAGE_EXPORT`.
-1. Generate a key by calling `psa_generate_key()`.
-1. Export the generated public key by calling `psa_export_public_key()`:
-```C
-    enum {
-        key_bits = 256,
-    };
-    psa_status_t status;
-    size_t exported_length = 0;
-    static uint8_t exported[PSA_KEY_EXPORT_ECC_PUBLIC_KEY_MAX_SIZE(key_bits)];
-    psa_key_attributes_t attributes = PSA_KEY_ATTRIBUTES_INIT;
-    psa_key_id_t key_id;
-
-    printf("Generate a key pair...\t");
-    fflush(stdout);
-
-    /* Initialize PSA Crypto */
-    status = psa_crypto_init();
-    if (status != PSA_SUCCESS) {
-        printf("Failed to initialize PSA Crypto\n");
-        return;
-    }
-
-    /* Generate a key */
-    psa_set_key_usage_flags(&attributes, PSA_KEY_USAGE_SIGN_HASH);
-    psa_set_key_algorithm(&attributes,
-                          PSA_ALG_DETERMINISTIC_ECDSA(PSA_ALG_SHA_256));
-    psa_set_key_type(&attributes,
-                     PSA_KEY_TYPE_ECC_KEY_PAIR(PSA_ECC_FAMILY_SECP_R1));
-    psa_set_key_bits(&attributes, key_bits);
-    status = psa_generate_key(&attributes, &key_id);
-    if (status != PSA_SUCCESS) {
-        printf("Failed to generate key\n");
-        return;
-    }
-    psa_reset_key_attributes(&attributes);
-
-    status = psa_export_public_key(key_id, exported, sizeof(exported),
-                                   &exported_length);
-    if (status != PSA_SUCCESS) {
-        printf("Failed to export public key %ld\n", status);
-        return;
-    }
-
-    printf("Exported a public key\n");
-
-    /* Destroy the key */
-    psa_destroy_key(key_id);
-
-    mbedtls_psa_crypto_free();
-```
-
-### More about the PSA Crypto API
-
-For more information about the PSA Crypto API, please see the
-[PSA Cryptography API Specification](https://arm-software.github.io/psa-api/crypto/).
diff --git a/include/mbedtls/config.h b/include/mbedtls/config.h
index 1e4d95e..acdb7ac 100644
--- a/include/mbedtls/config.h
+++ b/include/mbedtls/config.h
@@ -871,7 +871,7 @@
  * - Changes the behaviour of TLS 1.2 clients (not servers) when using the
  *   ECDHE-ECDSA key exchange (not other key exchanges) to make all ECC
  *   computations restartable:
- *   - ECDH operations from the key exchange, only for Short Weierstass
+ *   - ECDH operations from the key exchange, only for Short Weierstrass
  *     curves;
  *   - verification of the server's key exchange signature;
  *   - verification of the server's certificate chain;
diff --git a/include/mbedtls/pk.h b/include/mbedtls/pk.h
index a226e71..ec83551 100644
--- a/include/mbedtls/pk.h
+++ b/include/mbedtls/pk.h
@@ -402,6 +402,11 @@
  *                  Use \c mbedtls_pk_verify_ext( MBEDTLS_PK_RSASSA_PSS, ... )
  *                  to verify RSASSA_PSS signatures.
  *
+ * \note            If #MBEDTLS_USE_PSA_CRYPTO is enabled, the PSA crypto
+ *                  subsystem must have been initialized by calling
+ *                  psa_crypto_init() before calling this function,
+ *                  if the key might be an ECC (ECDSA) key.
+ *
  * \note            If hash_len is 0, then the length associated with md_alg
  *                  is used instead, or an error returned if it is invalid.
  *
diff --git a/include/mbedtls/ssl.h b/include/mbedtls/ssl.h
index 7836ece..26e4ec4 100644
--- a/include/mbedtls/ssl.h
+++ b/include/mbedtls/ssl.h
@@ -1544,6 +1544,10 @@
  *                 Calling mbedtls_ssl_setup again is not supported, even
  *                 if no session is active.
  *
+ * \note           If #MBEDTLS_USE_PSA_CRYPTO is enabled, the PSA crypto
+ *                 subsystem must have been initialized by calling
+ *                 psa_crypto_init() before calling this function.
+ *
  * \param ssl      SSL context
  * \param conf     SSL configuration to use
  *
@@ -3980,6 +3984,10 @@
  *                 in which case the datagram of the underlying transport that is
  *                 currently being processed might or might not contain further
  *                 DTLS records.
+ *
+ * \note           If #MBEDTLS_USE_PSA_CRYPTO is enabled, the PSA crypto
+ *                 subsystem must have been initialized by calling
+ *                 psa_crypto_init() before calling this function.
  */
 int mbedtls_ssl_handshake(mbedtls_ssl_context *ssl);
 
diff --git a/include/mbedtls/x509_crl.h b/include/mbedtls/x509_crl.h
index 895eca0..1405021 100644
--- a/include/mbedtls/x509_crl.h
+++ b/include/mbedtls/x509_crl.h
@@ -95,6 +95,10 @@
 /**
  * \brief          Parse a DER-encoded CRL and append it to the chained list
  *
+ * \note           If #MBEDTLS_USE_PSA_CRYPTO is enabled, the PSA crypto
+ *                 subsystem must have been initialized by calling
+ *                 psa_crypto_init() before calling this function.
+ *
  * \param chain    points to the start of the chain
  * \param buf      buffer holding the CRL data in DER format
  * \param buflen   size of the buffer
@@ -109,6 +113,10 @@
  *
  * \note           Multiple CRLs are accepted only if using PEM format
  *
+ * \note           If #MBEDTLS_USE_PSA_CRYPTO is enabled, the PSA crypto
+ *                 subsystem must have been initialized by calling
+ *                 psa_crypto_init() before calling this function.
+ *
  * \param chain    points to the start of the chain
  * \param buf      buffer holding the CRL data in PEM or DER format
  * \param buflen   size of the buffer
@@ -124,6 +132,10 @@
  *
  * \note           Multiple CRLs are accepted only if using PEM format
  *
+ * \note           If #MBEDTLS_USE_PSA_CRYPTO is enabled, the PSA crypto
+ *                 subsystem must have been initialized by calling
+ *                 psa_crypto_init() before calling this function.
+ *
  * \param chain    points to the start of the chain
  * \param path     filename to read the CRLs from (in PEM or DER encoding)
  *
diff --git a/include/mbedtls/x509_crt.h b/include/mbedtls/x509_crt.h
index 235e00c..466611f 100644
--- a/include/mbedtls/x509_crt.h
+++ b/include/mbedtls/x509_crt.h
@@ -283,6 +283,10 @@
  * \brief          Parse a single DER formatted certificate and add it
  *                 to the end of the provided chained list.
  *
+ * \note           If #MBEDTLS_USE_PSA_CRYPTO is enabled, the PSA crypto
+ *                 subsystem must have been initialized by calling
+ *                 psa_crypto_init() before calling this function.
+ *
  * \param chain    The pointer to the start of the CRT chain to attach to.
  *                 When parsing the first CRT in a chain, this should point
  *                 to an instance of ::mbedtls_x509_crt initialized through
@@ -344,6 +348,10 @@
  * \brief            Parse a single DER formatted certificate and add it
  *                   to the end of the provided chained list.
  *
+ * \note             If #MBEDTLS_USE_PSA_CRYPTO is enabled, the PSA crypto
+ *                   subsystem must have been initialized by calling
+ *                   psa_crypto_init() before calling this function.
+ *
  * \param chain      The pointer to the start of the CRT chain to attach to.
  *                   When parsing the first CRT in a chain, this should point
  *                   to an instance of ::mbedtls_x509_crt initialized through
@@ -394,6 +402,10 @@
  *                 temporary ownership of the CRT buffer until the CRT
  *                 is destroyed.
  *
+ * \note           If #MBEDTLS_USE_PSA_CRYPTO is enabled, the PSA crypto
+ *                 subsystem must have been initialized by calling
+ *                 psa_crypto_init() before calling this function.
+ *
  * \param chain    The pointer to the start of the CRT chain to attach to.
  *                 When parsing the first CRT in a chain, this should point
  *                 to an instance of ::mbedtls_x509_crt initialized through
@@ -434,6 +446,10 @@
  *                 long as the certificates are enclosed in the PEM specific
  *                 '-----{BEGIN/END} CERTIFICATE-----' delimiters.
  *
+ * \note           If #MBEDTLS_USE_PSA_CRYPTO is enabled, the PSA crypto
+ *                 subsystem must have been initialized by calling
+ *                 psa_crypto_init() before calling this function.
+ *
  * \param chain    The chain to which to add the parsed certificates.
  * \param buf      The buffer holding the certificate data in PEM or DER format.
  *                 For certificates in PEM encoding, this may be a concatenation
@@ -458,6 +474,10 @@
  *                 of failed certificates it encountered. If none complete
  *                 correctly, the first error is returned.
  *
+ * \note           If #MBEDTLS_USE_PSA_CRYPTO is enabled, the PSA crypto
+ *                 subsystem must have been initialized by calling
+ *                 psa_crypto_init() before calling this function.
+ *
  * \param chain    points to the start of the chain
  * \param path     filename to read the certificates from
  *
diff --git a/include/mbedtls/x509_csr.h b/include/mbedtls/x509_csr.h
index fa7ef04..5975584 100644
--- a/include/mbedtls/x509_csr.h
+++ b/include/mbedtls/x509_csr.h
@@ -82,6 +82,10 @@
  *
  * \note           CSR attributes (if any) are currently silently ignored.
  *
+ * \note           If #MBEDTLS_USE_PSA_CRYPTO is enabled, the PSA crypto
+ *                 subsystem must have been initialized by calling
+ *                 psa_crypto_init() before calling this function.
+ *
  * \param csr      CSR context to fill
  * \param buf      buffer holding the CRL data
  * \param buflen   size of the buffer
@@ -96,6 +100,10 @@
  *
  * \note           See notes for \c mbedtls_x509_csr_parse_der()
  *
+ * \note           If #MBEDTLS_USE_PSA_CRYPTO is enabled, the PSA crypto
+ *                 subsystem must have been initialized by calling
+ *                 psa_crypto_init() before calling this function.
+ *
  * \param csr      CSR context to fill
  * \param buf      buffer holding the CRL data
  * \param buflen   size of the buffer
diff --git a/library/ssl_msg.c b/library/ssl_msg.c
index a38e764..8a2ab7b 100644
--- a/library/ssl_msg.c
+++ b/library/ssl_msg.c
@@ -5429,8 +5429,10 @@
     n = (len < ssl->in_msglen)
         ? len : ssl->in_msglen;
 
-    memcpy(buf, ssl->in_offt, n);
-    ssl->in_msglen -= n;
+    if (len != 0) {
+        memcpy(buf, ssl->in_offt, n);
+        ssl->in_msglen -= n;
+    }
 
     /* Zeroising the plaintext buffer to erase unused application data
        from the memory. */
@@ -5506,7 +5508,9 @@
          */
         ssl->out_msglen  = len;
         ssl->out_msgtype = MBEDTLS_SSL_MSG_APPLICATION_DATA;
-        memcpy(ssl->out_msg, buf, len);
+        if (len > 0) {
+            memcpy(ssl->out_msg, buf, len);
+        }
 
         if ((ret = mbedtls_ssl_write_record(ssl, SSL_FORCE_FLUSH)) != 0) {
             MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_write_record", ret);
diff --git a/tests/suites/test_suite_ssl.function b/tests/suites/test_suite_ssl.function
index 1dec18d..39825ed 100644
--- a/tests/suites/test_suite_ssl.function
+++ b/tests/suites/test_suite_ssl.function
@@ -1052,6 +1052,12 @@
                                int buf_len, int *written,
                                const int expected_fragments)
 {
+    /* Verify that calling mbedtls_ssl_write with a NULL buffer and zero length is
+     * a valid no-op for TLS connections. */
+    if (ssl->conf->transport != MBEDTLS_SSL_TRANSPORT_DATAGRAM) {
+        TEST_ASSERT(mbedtls_ssl_write(ssl, NULL, 0) == 0);
+    }
+
     int ret = mbedtls_ssl_write(ssl, buf + *written, buf_len - *written);
     if (ret > 0) {
         *written += ret;
@@ -1090,6 +1096,12 @@
                               int buf_len, int *read,
                               int *fragments, const int expected_fragments)
 {
+    /* Verify that calling mbedtls_ssl_write with a NULL buffer and zero length is
+     * a valid no-op for TLS connections. */
+    if (ssl->conf->transport != MBEDTLS_SSL_TRANSPORT_DATAGRAM) {
+        TEST_ASSERT(mbedtls_ssl_read(ssl, NULL, 0) == 0);
+    }
+
     int ret = mbedtls_ssl_read(ssl, buf + *read, buf_len - *read);
     if (ret > 0) {
         (*fragments)++;