[PATCH] librt: fix NULL pointer dereference (bug 28213)

[Siddhesh Poyarekar]

On 8/9/21 6:51 PM, Siddhesh Poyarekar wrote:
> On 8/9/21 5:55 PM, Никита Попов via Libc-alpha wrote:
>> Helper thread frees copied attribute on NOTIFY_REMOVED message 
>> received from the OS kernel. Unfortunately, it fails to check whether 
>> copied attribute actually exists (data.attr != NULL). This worked 
>> earlier because free() checks passed pointer before actually 
>> attempting to release corresponding memory. But __pthread_attr_destroy 
>> assumes pointer is not NULL. So passing NULL pointer to 
>> __pthread_attr_destroy will result in segmentation fault. This 
>> scenario is possible if notification->sigev_notify_attributes == NULL 
>> (which means default thread attributes should be used).
> 
> Thank you, the fix looks good to me.  Do you have a test case to go with 
> it?

Also, I don't know if you have an FSF copyright assignment, but it's no 
longer necessary.  Please confirm that you're the original author and 
are authorized to contribute this patch by adding a DCO, i.e. add a 
Signed-off-by to indicate that.  See also:

https://developercertificate.org/

Thanks,
Siddhesh