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From:   =?UTF-8?q?Toke=20H=C3=B8iland-J=C3=B8rgensen?= <toke@redhat.com>
To:     David Howells <dhowells@redhat.com>,
        Herbert Xu <herbert@gondor.apana.org.au>,
        "David S. Miller" <davem@davemloft.net>
Cc:     =?UTF-8?q?Toke=20H=C3=B8iland-J=C3=B8rgensen?= <toke@redhat.com>,
        Tianjia Zhang <tianjia.zhang@linux.alibaba.com>,
        Gilad Ben-Yossef <gilad@benyossef.com>,
        keyrings@vger.kernel.org, linux-crypto@vger.kernel.org,
        stable@vger.kernel.org
Subject: [PATCH] crypto: public_key: check that pkey_algo is non-NULL before passing it to strcmp()
Date:   Tue, 12 Jan 2021 17:10:44 +0100
Message-Id: <20210112161044.3101-1-toke@redhat.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
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Precedence: bulk

When public_key_verify_signature() is called from
asymmetric_key_verify_signature(), the pkey_algo field of struct
public_key_signature will be NULL, which causes a NULL pointer dereference
in the strcmp() check. Fix this by adding a NULL check.

One visible manifestation of this is that userspace programs (such as the
'iwd' WiFi daemon) will be killed when trying to verify a TLS key using the
keyctl(2) interface.

Cc: stable@vger.kernel.org
Fixes: 215525639631 ("X.509: support OSCCA SM2-with-SM3 certificate verification")
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
---
 crypto/asymmetric_keys/public_key.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/crypto/asymmetric_keys/public_key.c b/crypto/asymmetric_keys/public_key.c
index 8892908ad58c..35b09e95a870 100644
--- a/crypto/asymmetric_keys/public_key.c
+++ b/crypto/asymmetric_keys/public_key.c
@@ -356,7 +356,7 @@ 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;
-- 
2.30.0