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: 2155256396 ("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>
Acked-by: Jarkko Sakkinen <jarkko@kernel.org>
Cc: stable@vger.kernel.org # v5.10+
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>