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Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.9.0 Subject: Re: [bug report] drm/ttm: Fix dummy res NULL ptr deref bug Content-Language: en-US To: Dan Carpenter References: From: Arunpravin Paneer Selvam In-Reply-To: X-ClientProxiedBy: PN2PR01CA0211.INDPRD01.PROD.OUTLOOK.COM (2603:1096:c01:ea::6) To MN2PR12MB4342.namprd12.prod.outlook.com (2603:10b6:208:264::7) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: 995de029-ef31-4e30-f450-08da7b8990f4 X-MS-TrafficTypeDiagnostic: PH8PR12MB7376:EE_ X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:255.255.255.255; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit 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 | > > 908 ret = ttm_bo_move_buffer(bo, placement, ctx); > 909 if (ret) > 910 return ret; > 911 } > 912 /* > 913 * We might need to add a TTM. > 914 */ > 915 if (!bo->resource || bo->resource->mem_type == TTM_PL_SYSTEM) { > ^^^^^^^^^^^^ > Checked too late. > > This NULL check was added deliberately based on a report from the kbuild > bot, but it's not clear why bo->resource is NULL at this point. Was the > patch tested? There is astable@vger.kernel.org but there is no Fixes > tag. > > 916 ret = ttm_tt_create(bo, true); > 917 if (ret) > > regards, > dan carpenter --------------uFfqQidilUGvwf6bR9kqlTFt Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: 7bit 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


   908			ret = ttm_bo_move_buffer(bo, placement, ctx);
   909			if (ret)
   910				return ret;
   911		}
   912		/*
   913		 * We might need to add a TTM.
   914		 */
   915		if (!bo->resource || bo->resource->mem_type == TTM_PL_SYSTEM) {
                     ^^^^^^^^^^^^
Checked too late.

This NULL check was added deliberately based on a report from the kbuild
bot, but it's not clear why bo->resource is NULL at this point.  Was the
patch tested?  There is a stable@vger.kernel.org but there is no Fixes
tag.

   916			ret = ttm_tt_create(bo, true);
   917			if (ret)

regards,
dan carpenter

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