diff --git a/ChangeLog b/ChangeLog
index 9f0bb40..de3b8ad 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -48,6 +48,7 @@
    * Deprecate the Blowfish error MBEDTLS_ERR_BLOWFISH_INVALID_KEY_LENGTH
      in favour of a new generic error MBEDTLS_ERR_BLOWFISH_BAD_INPUT_DATA.
    * Add validation checks for input parameters to functions in the CCM module.
+   * Add validation checks for input parameters to functions in the GCM module.
 
 New deprecations
    * Deprecate mbedtls_ctr_drbg_update and mbedtls_hmac_drbg_update
diff --git a/include/mbedtls/gcm.h b/include/mbedtls/gcm.h
index 93d15ee..fccabb0 100644
--- a/include/mbedtls/gcm.h
+++ b/include/mbedtls/gcm.h
@@ -85,7 +85,7 @@
  *                  cipher, nor set the key. For this purpose, use
  *                  mbedtls_gcm_setkey().
  *
- * \param ctx       The GCM context to initialize.
+ * \param ctx       The GCM context to initialize. This must not be \c NULL.
  */
 void mbedtls_gcm_init( mbedtls_gcm_context *ctx );
 
@@ -93,9 +93,10 @@
  * \brief           This function associates a GCM context with a
  *                  cipher algorithm and a key.
  *
- * \param ctx       The GCM context to initialize.
+ * \param ctx       The GCM context. This must be initialized.
  * \param cipher    The 128-bit block cipher to use.
- * \param key       The encryption key.
+ * \param key       The encryption key. This must be a readable buffer of at
+ *                  least \p keybits bits.
  * \param keybits   The key size in bits. Valid options are:
  *                  <ul><li>128 bits</li>
  *                  <li>192 bits</li>
@@ -122,7 +123,8 @@
  *                  authentic. You should use this function to perform encryption
  *                  only. For decryption, use mbedtls_gcm_auth_decrypt() instead.
  *
- * \param ctx       The GCM context to use for encryption or decryption.
+ * \param ctx       The GCM context to use for encryption or decryption. This
+ *                  must be initialized.
  * \param mode      The operation to perform:
  *                  - #MBEDTLS_GCM_ENCRYPT to perform authenticated encryption.
  *                    The ciphertext is written to \p output and the
@@ -136,21 +138,27 @@
  *                    calling this function in decryption mode.
  * \param length    The length of the input data, which is equal to the length
  *                  of the output data.
- * \param iv        The initialization vector.
+ * \param iv        The initialization vector. This must be a readable buffer of
+ *                  at least \p iv_len Bytes.
  * \param iv_len    The length of the IV.
- * \param add       The buffer holding the additional data.
+ * \param add       The buffer holding the additional data. This must be of at
+ *                  least that size in Bytes.
  * \param add_len   The length of the additional data.
- * \param input     The buffer holding the input data. Its size is \b length.
- * \param output    The buffer for holding the output data. It must have room
- *                  for \b length bytes.
+ * \param input     The buffer holding the input data. If \p length is greater
+ *                  than zero, this must be a readable buffer of at least that
+ *                  size in Bytes.
+ * \param output    The buffer for holding the output data. If \p length is greater
+ *                  than zero, this must be a writable buffer of at least that
+ *                  size in Bytes.
  * \param tag_len   The length of the tag to generate.
- * \param tag       The buffer for holding the tag.
+ * \param tag       The buffer for holding the tag. This must be a readable
+ *                  buffer of at least \p tag_len Bytes.
  *
  * \return          \c 0 if the encryption or decryption was performed
  *                  successfully. Note that in #MBEDTLS_GCM_DECRYPT mode,
  *                  this does not indicate that the data is authentic.
- * \return          #MBEDTLS_ERR_GCM_BAD_INPUT if the lengths are not valid or
- *                  a cipher-specific error code if the encryption
+ * \return          #MBEDTLS_ERR_GCM_BAD_INPUT if the lengths or pointers are
+ *                  not valid or a cipher-specific error code if the encryption
  *                  or decryption failed.
  */
 int mbedtls_gcm_crypt_and_tag( mbedtls_gcm_context *ctx,
@@ -173,23 +181,30 @@
  *                  input buffer. If the buffers overlap, the output buffer
  *                  must trail at least 8 Bytes behind the input buffer.
  *
- * \param ctx       The GCM context.
+ * \param ctx       The GCM context. This must be initialized.
  * \param length    The length of the ciphertext to decrypt, which is also
  *                  the length of the decrypted plaintext.
- * \param iv        The initialization vector.
+ * \param iv        The initialization vector. This must be a readable buffer
+ *                  of at least \p iv_len Bytes.
  * \param iv_len    The length of the IV.
- * \param add       The buffer holding the additional data.
+ * \param add       The buffer holding the additional data. This must be of at
+ *                  least that size in Bytes.
  * \param add_len   The length of the additional data.
- * \param tag       The buffer holding the tag to verify.
+ * \param tag       The buffer holding the tag to verify. This must be a
+ *                  readable buffer of at least \p tag_len Bytes.
  * \param tag_len   The length of the tag to verify.
- * \param input     The buffer holding the ciphertext. Its size is \b length.
- * \param output    The buffer for holding the decrypted plaintext. It must
- *                  have room for \b length bytes.
+ * \param input     The buffer holding the ciphertext. If \p length is greater
+ *                  than zero, this must be a readable buffer of at least that
+ *                  size.
+ * \param output    The buffer for holding the decrypted plaintext. If \p length
+ *                  is greater than zero, this must be a writable buffer of at
+ *                  least that size.
  *
  * \return          \c 0 if successful and authenticated.
  * \return          #MBEDTLS_ERR_GCM_AUTH_FAILED if the tag does not match.
- * \return          #MBEDTLS_ERR_GCM_BAD_INPUT if the lengths are not valid or
- *                  a cipher-specific error code if the decryption failed.
+ * \return          #MBEDTLS_ERR_GCM_BAD_INPUT if the lengths or pointers are
+ *                  not valid or a cipher-specific error code if the decryption
+ *                  failed.
  */
 int mbedtls_gcm_auth_decrypt( mbedtls_gcm_context *ctx,
                       size_t length,
@@ -206,15 +221,16 @@
  * \brief           This function starts a GCM encryption or decryption
  *                  operation.
  *
- * \param ctx       The GCM context.
+ * \param ctx       The GCM context. This must be initialized.
  * \param mode      The operation to perform: #MBEDTLS_GCM_ENCRYPT or
  *                  #MBEDTLS_GCM_DECRYPT.
- * \param iv        The initialization vector.
+ * \param iv        The initialization vector. This must be a readable buffer of
+ *                  at least \p iv_len Bytes.
  * \param iv_len    The length of the IV.
- * \param add       The buffer holding the additional data, or NULL
- *                  if \p add_len is 0.
- * \param add_len   The length of the additional data. If 0,
- *                  \p add is NULL.
+ * \param add       The buffer holding the additional data, or \c NULL
+ *                  if \p add_len is \c 0.
+ * \param add_len   The length of the additional data. If \c 0,
+ *                  \p add may be \c NULL.
  *
  * \return          \c 0 on success.
  */
@@ -237,11 +253,15 @@
  *                  input buffer. If the buffers overlap, the output buffer
  *                  must trail at least 8 Bytes behind the input buffer.
  *
- * \param ctx       The GCM context.
+ * \param ctx       The GCM context. This must be initialized.
  * \param length    The length of the input data. This must be a multiple of
  *                  16 except in the last call before mbedtls_gcm_finish().
- * \param input     The buffer holding the input data.
- * \param output    The buffer for holding the output data.
+ * \param input     The buffer holding the input data. If \p length is greater
+ *                  than zero, this must be a readable buffer of at least that
+ *                  size in Bytes.
+ * \param output    The buffer for holding the output data. If \p length is
+ *                  greater than zero, this must be a writable buffer of at
+ *                  least that size in Bytes.
  *
  * \return         \c 0 on success.
  * \return         #MBEDTLS_ERR_GCM_BAD_INPUT on failure.
@@ -258,9 +278,11 @@
  *                  It wraps up the GCM stream, and generates the
  *                  tag. The tag can have a maximum length of 16 Bytes.
  *
- * \param ctx       The GCM context.
- * \param tag       The buffer for holding the tag.
- * \param tag_len   The length of the tag to generate. Must be at least four.
+ * \param ctx       The GCM context. This must be initialized.
+ * \param tag       The buffer for holding the tag. This must be a readable
+ *                  buffer of at least \p tag_len Bytes.
+ * \param tag_len   The length of the tag to generate. This must be at least
+ *                  four.
  *
  * \return          \c 0 on success.
  * \return          #MBEDTLS_ERR_GCM_BAD_INPUT on failure.
@@ -273,7 +295,8 @@
  * \brief           This function clears a GCM context and the underlying
  *                  cipher sub-context.
  *
- * \param ctx       The GCM context to clear.
+ * \param ctx       The GCM context to clear. If this is \c NULL, the call has
+ *                  no effect. Otherwise, this must be initialized.
  */
 void mbedtls_gcm_free( mbedtls_gcm_context *ctx );
 
diff --git a/library/gcm.c b/library/gcm.c
index c486ef7..675926a 100644
--- a/library/gcm.c
+++ b/library/gcm.c
@@ -57,6 +57,12 @@
 
 #if !defined(MBEDTLS_GCM_ALT)
 
+/* Parameter validation macros */
+#define GCM_VALIDATE_RET( cond ) \
+    MBEDTLS_INTERNAL_VALIDATE_RET( cond, MBEDTLS_ERR_GCM_BAD_INPUT )
+#define GCM_VALIDATE( cond ) \
+    MBEDTLS_INTERNAL_VALIDATE( cond )
+
 /*
  * 32-bit integer manipulation macros (big endian)
  */
@@ -85,6 +91,7 @@
  */
 void mbedtls_gcm_init( mbedtls_gcm_context *ctx )
 {
+    GCM_VALIDATE( ctx != NULL );
     memset( ctx, 0, sizeof( mbedtls_gcm_context ) );
 }
 
@@ -164,6 +171,10 @@
     int ret;
     const mbedtls_cipher_info_t *cipher_info;
 
+    GCM_VALIDATE_RET( ctx != NULL );
+    GCM_VALIDATE_RET( key != NULL );
+    GCM_VALIDATE_RET( keybits == 128 || keybits == 192 || keybits == 256 );
+
     cipher_info = mbedtls_cipher_info_from_values( cipher, keybits, MBEDTLS_MODE_ECB );
     if( cipher_info == NULL )
         return( MBEDTLS_ERR_GCM_BAD_INPUT );
@@ -274,6 +285,10 @@
     const unsigned char *p;
     size_t use_len, olen = 0;
 
+    GCM_VALIDATE_RET( ctx != NULL );
+    GCM_VALIDATE_RET( iv != NULL );
+    GCM_VALIDATE_RET( add_len == 0 || add != NULL );
+
     /* IV and AD are limited to 2^64 bits, so 2^61 bytes */
     /* IV is not allowed to be zero length */
     if( iv_len == 0 ||
@@ -356,6 +371,10 @@
     unsigned char *out_p = output;
     size_t use_len, olen = 0;
 
+    GCM_VALIDATE_RET( ctx != NULL );
+    GCM_VALIDATE_RET( length == 0 || input != NULL );
+    GCM_VALIDATE_RET( length == 0 || output != NULL );
+
     if( output > input && (size_t) ( output - input ) < length )
         return( MBEDTLS_ERR_GCM_BAD_INPUT );
 
@@ -409,8 +428,14 @@
 {
     unsigned char work_buf[16];
     size_t i;
-    uint64_t orig_len = ctx->len * 8;
-    uint64_t orig_add_len = ctx->add_len * 8;
+    uint64_t orig_len;
+    uint64_t orig_add_len;
+
+    GCM_VALIDATE_RET( ctx != NULL );
+    GCM_VALIDATE_RET( tag != NULL );
+
+    orig_len = ctx->len * 8;
+    orig_add_len = ctx->add_len * 8;
 
     if( tag_len > 16 || tag_len < 4 )
         return( MBEDTLS_ERR_GCM_BAD_INPUT );
@@ -452,6 +477,13 @@
 {
     int ret;
 
+    GCM_VALIDATE_RET( ctx != NULL );
+    GCM_VALIDATE_RET( iv != NULL );
+    GCM_VALIDATE_RET( add_len == 0 || add != NULL );
+    GCM_VALIDATE_RET( length == 0 || input != NULL );
+    GCM_VALIDATE_RET( length == 0 || output != NULL );
+    GCM_VALIDATE_RET( tag != NULL );
+
     if( ( ret = mbedtls_gcm_starts( ctx, mode, iv, iv_len, add, add_len ) ) != 0 )
         return( ret );
 
@@ -480,6 +512,13 @@
     size_t i;
     int diff;
 
+    GCM_VALIDATE_RET( ctx != NULL );
+    GCM_VALIDATE_RET( iv != NULL );
+    GCM_VALIDATE_RET( add_len == 0 || add != NULL );
+    GCM_VALIDATE_RET( tag != NULL );
+    GCM_VALIDATE_RET( length == 0 || input != NULL );
+    GCM_VALIDATE_RET( length == 0 || output != NULL );
+
     if( ( ret = mbedtls_gcm_crypt_and_tag( ctx, MBEDTLS_GCM_DECRYPT, length,
                                    iv, iv_len, add, add_len,
                                    input, output, tag_len, check_tag ) ) != 0 )
@@ -502,6 +541,8 @@
 
 void mbedtls_gcm_free( mbedtls_gcm_context *ctx )
 {
+    if( ctx == NULL )
+        return;
     mbedtls_cipher_free( &ctx->cipher_ctx );
     mbedtls_platform_zeroize( ctx, sizeof( mbedtls_gcm_context ) );
 }
diff --git a/tests/CMakeLists.txt b/tests/CMakeLists.txt
index 58126be..9e15249 100644
--- a/tests/CMakeLists.txt
+++ b/tests/CMakeLists.txt
@@ -92,6 +92,7 @@
 add_test_suite(gcm gcm.aes192_de)
 add_test_suite(gcm gcm.aes256_de)
 add_test_suite(gcm gcm.camellia)
+add_test_suite(gcm gcm.misc)
 add_test_suite(hkdf)
 add_test_suite(hmac_drbg hmac_drbg.misc)
 add_test_suite(hmac_drbg hmac_drbg.no_reseed)
diff --git a/tests/suites/helpers.function b/tests/suites/helpers.function
index 3aa5cd6..2e227f0 100644
--- a/tests/suites/helpers.function
+++ b/tests/suites/helpers.function
@@ -632,4 +632,3 @@
     }
     return ret;
 }
-
diff --git a/tests/suites/test_suite_gcm.function b/tests/suites/test_suite_gcm.function
index 4d3bba1..1fcb681 100644
--- a/tests/suites/test_suite_gcm.function
+++ b/tests/suites/test_suite_gcm.function
@@ -103,6 +103,175 @@
 }
 /* END_CASE */
 
+/* BEGIN_CASE depends_on:MBEDTLS_CHECK_PARAMS:!MBEDTLS_PARAM_FAILED_ALT */
+void gcm_invalid_param( )
+{
+    mbedtls_gcm_context ctx;
+    unsigned char valid_buffer[] = { 0x01, 0x02, 0x03, 0x04, 0x05, 0x06 };
+    mbedtls_cipher_id_t valid_cipher = MBEDTLS_CIPHER_ID_AES;
+    int valid_mode = MBEDTLS_GCM_ENCRYPT;
+    int valid_len = sizeof(valid_buffer);
+    int valid_bitlen = 128, invalid_bitlen = 1;
+
+    mbedtls_gcm_init( &ctx );
+
+    /* mbedtls_gcm_init() */
+    TEST_INVALID_PARAM( mbedtls_gcm_init( NULL ) );
+
+    /* mbedtls_gcm_setkey */
+    TEST_INVALID_PARAM_RET(
+        MBEDTLS_ERR_GCM_BAD_INPUT,
+        mbedtls_gcm_setkey( NULL, valid_cipher, valid_buffer, valid_bitlen ) );
+    TEST_INVALID_PARAM_RET(
+        MBEDTLS_ERR_GCM_BAD_INPUT,
+        mbedtls_gcm_setkey( &ctx, valid_cipher, NULL, valid_bitlen ) );
+    TEST_INVALID_PARAM_RET(
+        MBEDTLS_ERR_GCM_BAD_INPUT,
+        mbedtls_gcm_setkey( &ctx, valid_cipher, valid_buffer, invalid_bitlen ) );
+
+    /* mbedtls_gcm_crypt_and_tag() */
+    TEST_INVALID_PARAM_RET(
+        MBEDTLS_ERR_GCM_BAD_INPUT,
+        mbedtls_gcm_crypt_and_tag( NULL, valid_mode, valid_len,
+                                   valid_buffer, valid_len,
+                                   valid_buffer, valid_len,
+                                   valid_buffer, valid_buffer,
+                                   valid_len, valid_buffer ) );
+    TEST_INVALID_PARAM_RET(
+        MBEDTLS_ERR_GCM_BAD_INPUT,
+        mbedtls_gcm_crypt_and_tag( &ctx, valid_mode, valid_len,
+                                   NULL, valid_len,
+                                   valid_buffer, valid_len,
+                                   valid_buffer, valid_buffer,
+                                   valid_len, valid_buffer ) );
+    TEST_INVALID_PARAM_RET(
+        MBEDTLS_ERR_GCM_BAD_INPUT,
+        mbedtls_gcm_crypt_and_tag( &ctx, valid_mode, valid_len,
+                                   valid_buffer, valid_len,
+                                   NULL, valid_len,
+                                   valid_buffer, valid_buffer,
+                                   valid_len, valid_buffer ) );
+    TEST_INVALID_PARAM_RET(
+        MBEDTLS_ERR_GCM_BAD_INPUT,
+        mbedtls_gcm_crypt_and_tag( &ctx, valid_mode, valid_len,
+                                   valid_buffer, valid_len,
+                                   valid_buffer, valid_len,
+                                   NULL, valid_buffer,
+                                   valid_len, valid_buffer ) );
+    TEST_INVALID_PARAM_RET(
+        MBEDTLS_ERR_GCM_BAD_INPUT,
+        mbedtls_gcm_crypt_and_tag( &ctx, valid_mode, valid_len,
+                                   valid_buffer, valid_len,
+                                   valid_buffer, valid_len,
+                                   valid_buffer, NULL,
+                                   valid_len, valid_buffer ) );
+    TEST_INVALID_PARAM_RET(
+        MBEDTLS_ERR_GCM_BAD_INPUT,
+        mbedtls_gcm_crypt_and_tag( &ctx, valid_mode, valid_len,
+                                   valid_buffer, valid_len,
+                                   valid_buffer, valid_len,
+                                   valid_buffer, valid_buffer,
+                                   valid_len, NULL ) );
+
+    /* mbedtls_gcm_auth_decrypt() */
+    TEST_INVALID_PARAM_RET(
+        MBEDTLS_ERR_GCM_BAD_INPUT,
+        mbedtls_gcm_auth_decrypt( NULL, valid_len,
+                                  valid_buffer, valid_len,
+                                  valid_buffer, valid_len,
+                                  valid_buffer, valid_len,
+                                  valid_buffer, valid_buffer) );
+    TEST_INVALID_PARAM_RET(
+        MBEDTLS_ERR_GCM_BAD_INPUT,
+        mbedtls_gcm_auth_decrypt( &ctx, valid_len,
+                                  NULL, valid_len,
+                                  valid_buffer, valid_len,
+                                  valid_buffer, valid_len,
+                                  valid_buffer, valid_buffer) );
+    TEST_INVALID_PARAM_RET(
+        MBEDTLS_ERR_GCM_BAD_INPUT,
+        mbedtls_gcm_auth_decrypt( &ctx, valid_len,
+                                  valid_buffer, valid_len,
+                                  NULL, valid_len,
+                                  valid_buffer, valid_len,
+                                  valid_buffer, valid_buffer) );
+    TEST_INVALID_PARAM_RET(
+        MBEDTLS_ERR_GCM_BAD_INPUT,
+        mbedtls_gcm_auth_decrypt( &ctx, valid_len,
+                                  valid_buffer, valid_len,
+                                  valid_buffer, valid_len,
+                                  NULL, valid_len,
+                                  valid_buffer, valid_buffer) );
+    TEST_INVALID_PARAM_RET(
+        MBEDTLS_ERR_GCM_BAD_INPUT,
+        mbedtls_gcm_auth_decrypt( &ctx, valid_len,
+                                  valid_buffer, valid_len,
+                                  valid_buffer, valid_len,
+                                  valid_buffer, valid_len,
+                                  NULL, valid_buffer) );
+    TEST_INVALID_PARAM_RET(
+        MBEDTLS_ERR_GCM_BAD_INPUT,
+        mbedtls_gcm_auth_decrypt( &ctx, valid_len,
+                                  valid_buffer, valid_len,
+                                  valid_buffer, valid_len,
+                                  valid_buffer, valid_len,
+                                  valid_buffer, NULL) );
+
+    /* mbedtls_gcm_starts() */
+    TEST_INVALID_PARAM_RET(
+        MBEDTLS_ERR_GCM_BAD_INPUT,
+        mbedtls_gcm_starts( NULL, valid_mode,
+                            valid_buffer, valid_len,
+                            valid_buffer, valid_len ) );
+
+    TEST_INVALID_PARAM_RET(
+        MBEDTLS_ERR_GCM_BAD_INPUT,
+        mbedtls_gcm_starts( &ctx, valid_mode,
+                            NULL, valid_len,
+                            valid_buffer, valid_len ) );
+
+    TEST_INVALID_PARAM_RET(
+        MBEDTLS_ERR_GCM_BAD_INPUT,
+        mbedtls_gcm_starts( &ctx, valid_mode,
+                            valid_buffer, valid_len,
+                            NULL, valid_len ) );
+
+    /* mbedtls_gcm_update() */
+    TEST_INVALID_PARAM_RET(
+        MBEDTLS_ERR_GCM_BAD_INPUT,
+        mbedtls_gcm_update( NULL, valid_len,
+                            valid_buffer, valid_buffer ) );
+    TEST_INVALID_PARAM_RET(
+        MBEDTLS_ERR_GCM_BAD_INPUT,
+        mbedtls_gcm_update( &ctx, valid_len,
+                            NULL, valid_buffer ) );
+    TEST_INVALID_PARAM_RET(
+        MBEDTLS_ERR_GCM_BAD_INPUT,
+        mbedtls_gcm_update( &ctx, valid_len,
+                            valid_buffer, NULL ) );
+
+    /* mbedtls_gcm_finish() */
+    TEST_INVALID_PARAM_RET(
+        MBEDTLS_ERR_GCM_BAD_INPUT,
+        mbedtls_gcm_finish( NULL, valid_buffer, valid_len ) );
+    TEST_INVALID_PARAM_RET(
+        MBEDTLS_ERR_GCM_BAD_INPUT,
+        mbedtls_gcm_finish( &ctx, NULL, valid_len ) );
+
+exit:
+    mbedtls_gcm_free( &ctx );
+}
+/* END_CASE */
+
+/* BEGIN_CASE */
+void gcm_valid_param( )
+{
+    TEST_VALID_PARAM( mbedtls_gcm_free( NULL ) );
+exit:
+    return;
+}
+/* END_CASE */
+
 /* BEGIN_CASE depends_on:MBEDTLS_SELF_TEST */
 void gcm_selftest(  )
 {
diff --git a/tests/suites/test_suite_gcm.misc.data b/tests/suites/test_suite_gcm.misc.data
new file mode 100644
index 0000000..cf01526
--- /dev/null
+++ b/tests/suites/test_suite_gcm.misc.data
@@ -0,0 +1,5 @@
+GCM - Invalid parameters
+gcm_invalid_param:
+
+GCM - Valid parameters
+gcm_valid_param: