commit cd74298c83446e026b55acce557c7d4eca8a4fa1
author Gilles Peskine <Gilles.Peskine@arm.com> Mon Dec 13 16:57:47 2021 +0100
committer Gilles Peskine <Gilles.Peskine@arm.com> Mon Dec 13 17:01:25 2021 +0100
tree e09e01c0296c8e32571e19acb2d3ee1c0719f15e
parent a4174312da06da490df076845577a076783d28f5

mbedtls_cipher_check_tag: jump on error for more robustness to refactoring

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>

library/cipher.c

diff --git a/library/cipher.c b/library/cipher.c
index 70f2d00..03e84c6 100644
--- a/library/cipher.c
+++ b/library/cipher.c
@@ -1201,7 +1201,10 @@
 
         /* Check the tag in "constant-time" */
         if( mbedtls_ct_memcmp( tag, check_tag, tag_len ) != 0 )
+        {
             ret = MBEDTLS_ERR_CIPHER_AUTH_FAILED;
+            goto exit;
+        }
     }
 #endif /* MBEDTLS_GCM_C */
 
@@ -1221,10 +1224,14 @@
 
         /* Check the tag in "constant-time" */
         if( mbedtls_ct_memcmp( tag, check_tag, tag_len ) != 0 )
+        {
             ret = MBEDTLS_ERR_CIPHER_AUTH_FAILED;
+            goto exit;
+        }
     }
 #endif /* MBEDTLS_CHACHAPOLY_C */
 
+exit:
     mbedtls_platform_zeroize( check_tag, tag_len );
     return( ret );
 }