- David Howells

From: David Howells <dhowells@redhat.com>
To: torvalds@linux-foundation.org
Cc: Tobias Markus <tobias@markus-regensburg.de>,
	Tianjia Zhang <tianjia.zhang@linux.alibaba.com>,
	dhowells@redhat.com, keyrings@vger.kernel.org,
	linux-crypto@vger.kernel.org,
	linux-security-module@vger.kernel.org, stable@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: 
Date: Tue, 19 Jan 2021 00:10:33 +0000	[thread overview]
Message-ID: <163546.1611015033@warthog.procyon.org.uk> (raw)


From: Tianjia Zhang <tianjia.zhang@linux.alibaba.com>

On the following call path, `sig->pkey_algo` is not assigned
in asymmetric_key_verify_signature(), which causes runtime
crash in public_key_verify_signature().

  keyctl_pkey_verify
    asymmetric_key_verify_signature
      verify_signature
        public_key_verify_signature

This patch simply check this situation and fixes the crash
caused by NULL pointer.

Fixes: 215525639631 ("X.509: support OSCCA SM2-with-SM3 certificate verification")
Reported-by: Tobias Markus <tobias@markus-regensburg.de>
Signed-off-by: Tianjia Zhang <tianjia.zhang@linux.alibaba.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-and-tested-by: Toke Høiland-Jørgensen <toke@redhat.com>
Tested-by: João Fonseca <jpedrofonseca@ua.pt>
Cc: stable@vger.kernel.org # v5.10+
---

 crypto/asymmetric_keys/public_key.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/crypto/asymmetric_keys/public_key.c b/crypto/asymmetric_keys/public_key.c
index 8892908ad58c..788a4ba1e2e7 100644
--- a/crypto/asymmetric_keys/public_key.c
+++ b/crypto/asymmetric_keys/public_key.c
@@ -356,7 +356,8 @@ int public_key_verify_signature(const struct public_key *pkey,
 	if (ret)
 		goto error_free_key;
 
-	if (strcmp(sig->pkey_algo, "sm2") == 0 && sig->data_size) {
+	if (sig->pkey_algo && strcmp(sig->pkey_algo, "sm2") == 0 &&
+	    sig->data_size) {
 		ret = cert_sig_digest_update(sig, tfm);
 		if (ret)
 			goto error_free_key;

