From: "Christian König" <christian.koenig@amd.com>
To: Arunpravin Paneer Selvam <arunpravin.paneerselvam@amd.com>,
Dan Carpenter <dan.carpenter@oracle.com>
Cc: dri-devel@lists.freedesktop.org
Subject: Re: [bug report] drm/ttm: Fix dummy res NULL ptr deref bug
Date: Sun, 14 Aug 2022 19:50:26 +0200 [thread overview]
Message-ID: <35ff4c21-c305-6fda-f54e-1f9a141c5879@amd.com> (raw)
In-Reply-To: <9433a0ee-ef19-86d4-e4fd-8ccff53ff5a7@amd.com>
Am 14.08.22 um 08:00 schrieb Arunpravin Paneer Selvam:
> Hi Dan,
>
> On 8/11/2022 5:26 PM, Dan Carpenter wrote:
>> On Thu, Aug 11, 2022 at 04:36:33PM +0530, Arunpravin Paneer Selvam
>> wrote:
>>> Hi Dan,
>>>
>>> drm-misc-fixes doesn't have the updated ttm_bo.c file, we have the
>>> updated
>>> ttm_bo.c version in
>>> drm-misc-next branch. Please find below for the line number 907.
>>>
>>> On 8/11/2022 3:25 PM, Dan Carpenter wrote:
>>>> Hello Arunpravin Paneer Selvam,
>>>>
>>>> This is a semi-automatic email about new static checker warnings.
>>>>
>>>> The patch cf4b7387c0a8: "drm/ttm: Fix dummy res NULL ptr deref bug"
>>>> from Aug 9, 2022, leads to the following Smatch complaint:
>>>>
>>>> drivers/gpu/drm/ttm/ttm_bo.c:915 ttm_bo_validate()
>>>> warn: variable dereferenced before check 'bo->resource' (see
>>>> line 907)
>>>>
>>>> drivers/gpu/drm/ttm/ttm_bo.c
>>>> 906 */
>>>> 907 if (!ttm_resource_compat(bo->resource, placement)) {
>>>> ^^^^^^^^^^^^
>>>> Unchecked dereference here inside the function.
>>> |if (!bo->resource || !ttm_resource_compat(bo->resource, placement))
>>> { we
>>> have this version in drm-misc-next Regards, Arun |
>>>
>> Huh... That's very interesting. It appears there was a bug in
>> drm-misc-next, we applied the fix to the wrong tree, and now both trees
>> are wrong. The drm-misc-next tree still has the bug and the other tree
>> has a static checker warning about nonsensical NULL checks.
>>
>> Eventually drm-misc-next will get merged and everything will work. Is
>> it too late to remove the bogus "CC: stable@vger.kernel.org"?
> I will look into this problem.
Mhm, if I'm not completely mistaken the "CC: stable@vger.kernel.org" is
actually correct, we just need to limit to which version it applies.
>> This could have been avoided if the NULL dereference fix had a Fixes
>> tag.
> I should have added the below tag
> Fixes: 347987a2cf0d ("drm/ttm: rename and cleanup ttm_bo_init")
WAIT! That's not the correct one. This patch just made the problem more
obvious.
The real one is bfa3357ef9ab drm/ttm: allocate resource object instead
of embedding it v2
Regards,
Christian.
>
> I will check on this.
>
> Thanks,
> Arun
>>
>> regards,
>> dan carpenter
>>
>
prev parent reply other threads:[~2022-08-14 17:50 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-11 9:55 [bug report] drm/ttm: Fix dummy res NULL ptr deref bug Dan Carpenter
2022-08-11 11:06 ` Arunpravin Paneer Selvam
2022-08-11 11:56 ` Dan Carpenter
2022-08-14 6:00 ` Arunpravin Paneer Selvam
2022-08-14 17:50 ` Christian König [this message]
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