Re: [PATCH-for-6.0?] mptsas: remove unused MPTSASState.pending (CVE-2021-3392)

[Philippe Mathieu-Daudé]

On 4/18/21 7:14 AM, Philippe Mathieu-Daudé wrote:
> On 4/16/21 1:33 PM, Philippe Mathieu-Daudé wrote:
>> Cc'ing maintainers.
>>
>> On 4/16/21 1:27 PM, Philippe Mathieu-Daudé wrote:
>>> On 4/16/21 12:22 PM, Michael Tokarev wrote:
>>>> During previous attempt to fix CVE-2021-3392 it was discovered
>>>> that MPTSASState.pending is actually not used. So instead of
>>>> fixing the prob, just remove the offending code entirely
>>>
>>> What problem?
> 
> Digging a bit I found:
> https://bugs.launchpad.net/qemu/+bug/1914236
> and Paolo's comment:
> https://lists.gnu.org/archive/html/qemu-devel/2021-02/msg02660.html
> 
> So your patch now makes sense, but please:
> 
> 1/ Reword including Prasad description:
> 
> """
> While processing SCSI i/o requests in mptsas_process_scsi_io_request(),
> the Megaraid emulator appends new MPTSASRequest object 'req' to
> the 's->pending' queue. In case of an error, this same object gets
> dequeued in mptsas_free_request() only if SCSIRequest object
> 'req->sreq' is initialised. This may lead to a use-after-free issue.
> 
> Since MPTSASState.pending is actually not used, simply remove it.
> """
> 
> 2/ Add:
> 
> BugLink: https://bugs.launchpad.net/qemu/+bug/1914236 (CVE-2021-3392)
> Fixes: e351b826112 ("hw: Add support for LSI SAS1068 (mptsas) device")

And:

Reported-by: Cheolwoo Myung <cwmyung@snu.ac.kr>

> With it:
> Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
> 
>>>> Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
>>>> Cc: Prasad J Pandit <pjp@fedoraproject.org>
>>>> Cc: qemu-stable@nongnu.org
>>>> ---
>>>>  hw/scsi/mptsas.c | 4 ----
>>>>  hw/scsi/mptsas.h | 1 -
>>>>  2 files changed, 5 deletions(-)