Call setbuf when reading or writing files: programs
After opening a file containing sensitive data, call mbedtls_setbuf() to
disable buffering. This way, we don't expose sensitive data to a memory
disclosure vulnerability in a buffer outside our control.
This commit adds a call to mbedtls_setbuf() after each call to fopen(),
but only in sample programs that were calling mbedtls_platform_zeroize().
Don't bother protecting stdio buffers in programs where application buffers
weren't protected.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/programs/aes/crypt_and_hash.c b/programs/aes/crypt_and_hash.c
index 74ea88c..fa874b2 100644
--- a/programs/aes/crypt_and_hash.c
+++ b/programs/aes/crypt_and_hash.c
@@ -171,6 +171,10 @@
goto exit;
}
+ /* Ensure no stdio buffering of secrets, as such buffers cannot be wiped. */
+ mbedtls_setbuf( fin, NULL );
+ mbedtls_setbuf( fout, NULL );
+
/*
* Read the Cipher and MD from the command line
*/