Check whether ctx->pctx != NULL

If it is NULL, ctx->pctx->pmeth dereference will cause a crash.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Reviewed-by: Tom Cosgrove <tom.cosgrove@arm.com>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/26176)

diff --git a/crypto/evp/m_sigver.c b/crypto/evp/m_sigver.c
index f6a6810615e3f403ac3eefa36adb11a9262db7af..a58c46bd062b943269828ea315fe9bdc20298385 100644 (file)
--- a/crypto/evp/m_sigver.c
+++ b/crypto/evp/m_sigver.c
@@ -684,13 +684,17 @@ int EVP_DigestVerify(EVP_MD_CTX *ctx, const unsigned char *sigret,
 {
     EVP_PKEY_CTX *pctx = ctx->pctx;
 
+    if (pctx == NULL) {
+        ERR_raise(ERR_LIB_EVP, EVP_R_INITIALIZATION_ERROR);
+        return -1;
+    }
+
     if ((ctx->flags & EVP_MD_CTX_FLAG_FINALISED) != 0) {
         ERR_raise(ERR_LIB_EVP, EVP_R_FINAL_ERROR);
         return 0;
     }
 
-    if (pctx != NULL
-            && pctx->operation == EVP_PKEY_OP_VERIFYCTX
+    if (pctx->operation == EVP_PKEY_OP_VERIFYCTX
             && pctx->op.sig.algctx != NULL
             && pctx->op.sig.signature != NULL) {
         if (pctx->op.sig.signature->digest_verify != NULL) {
@@ -701,8 +705,8 @@ int EVP_DigestVerify(EVP_MD_CTX *ctx, const unsigned char *sigret,
         }
     } else {
         /* legacy */
-        if (ctx->pctx->pmeth != NULL && ctx->pctx->pmeth->digestverify != NULL)
-            return ctx->pctx->pmeth->digestverify(ctx, sigret, siglen, tbs, tbslen);
+        if (pctx->pmeth != NULL && pctx->pmeth->digestverify != NULL)
+            return pctx->pmeth->digestverify(ctx, sigret, siglen, tbs, tbslen);
     }
     if (EVP_DigestVerifyUpdate(ctx, tbs, tbslen) <= 0)
         return -1;