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Subject: Re: [PATCH] crypto: public_key: check that pkey_algo is non-NULL
 before passing it to strcmp()
To:     =?UTF-8?Q?Toke_H=c3=b8iland-J=c3=b8rgensen?= <toke@redhat.com>,
        David Howells <dhowells@redhat.com>,
        Herbert Xu <herbert@gondor.apana.org.au>,
        "David S. Miller" <davem@davemloft.net>
Cc:     Gilad Ben-Yossef <gilad@benyossef.com>, keyrings@vger.kernel.org,
        linux-crypto@vger.kernel.org, stable@vger.kernel.org
References: <20210112161044.3101-1-toke@redhat.com>
From:   Tianjia Zhang <tianjia.zhang@linux.alibaba.com>
Message-ID: <d7a50628-5559-a054-bc47-2d45746eb503@linux.alibaba.com>
Date:   Wed, 13 Jan 2021 10:39:15 +0800
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Hi,

I have fixed this problem last week. Still thanks for your fixing.
patch is here: https://lkml.org/lkml/2021/1/7/201

Best regards,
Tianjia

On 1/13/21 12:10 AM, Toke Høiland-Jørgensen wrote:
> 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;
>