Thank you all! Regards, Lingkai
________________________________ From: Christian König <christian.koe...@amd.com> Sent: Thursday, December 7, 2023 1:55 PM To: Tvrtko Ursulin <tvrtko.ursu...@linux.intel.com>; Linus Walleij <linus.wall...@linaro.org>; Lingkai Dong <lingkai.d...@arm.com>; Tvrtko Ursulin <tvrtko.ursu...@intel.com> Cc: nd <n...@arm.com>; dri-devel@lists.freedesktop.org <dri-devel@lists.freedesktop.org> Subject: Re: [PATCH] drm: Fix FD ownership check in drm_master_check_perm() Am 07.12.23 um 11:22 schrieb Tvrtko Ursulin: > > > On 07/12/2023 10:18, Christian König wrote: >> Am 07.12.23 um 11:12 schrieb Linus Walleij: >>> On Wed, Dec 6, 2023 at 2:52 PM Lingkai Dong <lingkai.d...@arm.com> >>> wrote: >>> >>>> The DRM subsystem keeps a record of the owner of a DRM device file >>>> descriptor using thread group ID (TGID) instead of process ID >>>> (PID), to >>>> ensures all threads within the same userspace process are >>>> considered the >>>> owner. However, the DRM master ownership check compares the current >>>> thread's PID against the record, so the thread is incorrectly >>>> considered to >>>> be not the FD owner if the PID is not equal to the TGID. This >>>> causes DRM >>>> ioctls to be denied master privileges, even if the same thread that >>>> opened >>>> the FD performs an ioctl. Fix this by checking TGID. >>>> >>>> Fixes: 4230cea89cafb ("drm: Track clients by tgid and not tid") >>>> Signed-off-by: Lingkai Dong <lingkai.d...@arm.com> >>> Paging the patch author (Tvrko) and committer (Christian). >>> Here is the patch if you don't have it in your mailbox: >>> https://lore.kernel.org/dri-devel/pa6pr08mb107665920be9a96658cda04ce88...@pa6pr08mb10766.eurprd08.prod.outlook.com/ >>> >>> >>> I'm seeing this as well (on Android). >>> >>> Tvrko, Christian: can you look at this? >> >> Good catch, looks like we missed this occasion while switching from >> PID to TGID. > > Oops, yes.. > > Reviewed-by: Tvrtko Ursulin <tvrtko.ursu...@intel.com> > >>> Will you apply it to the AMD tree for fixes if it looks OK >>> or does it go elsewhere? >> >> I can push this to drm-misc-fixes as long as nobody objects in the >> next hour or so. >> >> CC: stable? If yes which versions? > > Cc: <sta...@vger.kernel.org> # v6.4+ And pushed to drm-misc-fixes. Thanks, Christian. > > Regards, > > Tvrtko