Re:

[Jarkko Sakkinen]

On Tue, Jan 19, 2021 at 12:10:33AM +0000, David Howells wrote:
> 
> From: Tianjia Zhang <tianjia.zhang@xxxxxxxxxxxxxxxxx>
> 
> 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@xxxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Tianjia Zhang <tianjia.zhang@xxxxxxxxxxxxxxxxx>
> Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
> Reviewed-and-tested-by: Toke Høiland-Jørgensen <toke@xxxxxxxxxx>
> Tested-by: João Fonseca <jpedrofonseca@xxxxx>
> Cc: stable@xxxxxxxxxxxxxxx # v5.10+
> ---

For what it's worth

Acked-by: Jarkko Sakkinen <jarkko@xxxxxxxxxx>

/Jarkko

> 
>  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;
> 
>