1 files changed, 3 insertions, 0 deletions
diff --git a/crypto/rsa/rsa_pk1.c b/crypto/rsa/rsa_pk1.c
index 9094b1a..f1eabf1 100644
--- a/crypto/rsa/rsa_pk1.c
+++ b/crypto/rsa/rsa_pk1.c
@@ -128,6 +128,9 @@ int ossl_rsa_padding_add_PKCS1_type_2_ex(OSSL_LIB_CTX *libctx, unsigned char *to
     if (flen > (tlen - RSA_PKCS1_PADDING_SIZE)) {
         ERR_raise(ERR_LIB_RSA, RSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE);
         return 0;
+    } else if (flen < 0) {
+        ERR_raise(ERR_LIB_RSA, RSA_R_INVALID_LENGTH);
+        return 0;
     }
 
     p = (unsigned char *)to;