Fix for memory leak in RSA-SSA signing

Fix in mbedtls_rsa_rsassa_pkcs1_v15_sign() in rsa.c. Resolves github issue #372

2 files changed, 9 insertions, 1 deletions

diff --git a/ChangeLog b/ChangeLog
index f306742..2a81894 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -7,6 +7,8 @@ Bugfix
    * Fix bug in certificate validation that caused valid chains to be rejected
      when the first intermediate certificate has pathLenConstraint=0. Found by
      Nicholas Wilson. Introduced in mbed TLS 1.3.15. #280
+   * Removed potential leak in mbedtls_rsa_rsassa_pkcs1_v15_sign(), found by
+     JayaraghavendranK. #372
 
 = mbed TLS 1.3.15 released 2015-11-04
 
diff --git a/library/rsa.c b/library/rsa.c
index 59ec35f..0cb0e7d 100644
--- a/library/rsa.c
+++ b/library/rsa.c
@@ -1082,9 +1082,15 @@ int rsa_rsassa_pkcs1_v15_sign( rsa_context *ctx,
      * temporary buffer and check it before returning it.
      */
     sig_try = polarssl_malloc( ctx->len );
+    if( sig_try == NULL )
+        return( POLARSSL_ERR_MPI_MALLOC_FAILED );
+
     verif   = polarssl_malloc( ctx->len );
-    if( sig_try == NULL || verif == NULL )
+    if( verif == NULL )
+    {
+        polarssl_free( sig_try );
         return( POLARSSL_ERR_MPI_MALLOC_FAILED );
+    }
 
     MPI_CHK( rsa_private( ctx, f_rng, p_rng, sig, sig_try ) );
     MPI_CHK( rsa_public( ctx, sig_try, verif ) );