Fix coverity CID #1452773 - Dereference before NULL check in EVP_DigestFinal_ex()

Reviewed-by: Tomas Mraz <tmraz@fedoraproject.org>
(Merged from https://github.com/openssl/openssl/pull/12628)

diff --git a/crypto/evp/digest.c b/crypto/evp/digest.c
index f5ec573828aba95a537a96ce05e1d38b453d8639..f9ba59ca6352b7f356aae3aa390734667354c9d8 100644 (file)
--- a/crypto/evp/digest.c
+++ b/crypto/evp/digest.c
@@ -367,11 +367,18 @@ int EVP_DigestFinal(EVP_MD_CTX *ctx, unsigned char *md, unsigned int *size)
 /* The caller can assume that this removes any secret data from the context */
 int EVP_DigestFinal_ex(EVP_MD_CTX *ctx, unsigned char *md, unsigned int *isize)
 {
-    int ret;
+    int ret, sz;
     size_t size = 0;
-    size_t mdsize = EVP_MD_size(ctx->digest);
+    size_t mdsize = 0;
 
-    if (ctx->digest == NULL || ctx->digest->prov == NULL)
+    if (ctx->digest == NULL)
+        return 0;
+
+    sz = EVP_MD_size(ctx->digest);
+    if (sz < 0)
+        return 0;
+    mdsize = sz;
+    if (ctx->digest->prov == NULL)
         goto legacy;
 
     if (ctx->digest->dfinal == NULL) {