diff mbox series

X.509: Fix crash caused by NULL pointer

Message ID 20210107092855.76093-1-tianjia.zhang@linux.alibaba.com (mailing list archive)
State New
Headers show
Series X.509: Fix crash caused by NULL pointer | expand

Commit Message

Tianjia Zhang Jan. 7, 2021, 9:28 a.m. UTC
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")
Cc: stable@vger.kernel.org # v5.10+
Reported-by: Tobias Markus <tobias@markus-regensburg.de>
Signed-off-by: Tianjia Zhang <tianjia.zhang@linux.alibaba.com>
---
 crypto/asymmetric_keys/public_key.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

Comments

David Howells Jan. 7, 2021, 10:58 a.m. UTC | #1
Tianjia Zhang <tianjia.zhang@linux.alibaba.com> wrote:

> 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")
> Cc: stable@vger.kernel.org # v5.10+
> Reported-by: Tobias Markus <tobias@markus-regensburg.de>
> Signed-off-by: Tianjia Zhang <tianjia.zhang@linux.alibaba.com>

Looks reasonable:

Acked-by: David Howells <dhowells@redhat.com>

I wonder, though, if cert_sig_digest_update() should be obtained by some sort
of function pointer.  It doesn't really seem to belong in this file.  But this
is a separate issue.

David
Tianjia Zhang Jan. 13, 2021, 3:02 a.m. UTC | #2
On 1/7/21 6:58 PM, David Howells wrote:
> Tianjia Zhang <tianjia.zhang@linux.alibaba.com> wrote:
> 
>> 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")
>> Cc: stable@vger.kernel.org # v5.10+
>> Reported-by: Tobias Markus <tobias@markus-regensburg.de>
>> Signed-off-by: Tianjia Zhang <tianjia.zhang@linux.alibaba.com>
> 
> Looks reasonable:
> 
> Acked-by: David Howells <dhowells@redhat.com>
> 
> I wonder, though, if cert_sig_digest_update() should be obtained by some sort
> of function pointer.  It doesn't really seem to belong in this file.  But this
> is a separate issue.
> 
> David
> 

Yes, this is indeed the logic of the SM2 module. I have tried to 
dynamically load and obtain the pointer of this function through 
`request_module` before, but this method still does not seem very 
suitable. Here are some unfinished codes I tried before:

https://github.com/uudiin/linux/commit/55bca48c6282415d94c53a7692622d544da99342

It would be great if you have some good experience to share with me, I 
will continue to try to optimize this code.

Best regards,
Tianjia
diff mbox series

Patch

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;