The patch below does not apply to the 6.6-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.6.y git checkout FETCH_HEAD git cherry-pick -x 5a6c9a05e55cb2972396cc991af9d74c8c15029a # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2023121851-roamer-gravel-ddbe@gregkh' --subject-prefix 'PATCH 6.6.y' HEAD^..

Possible dependencies:

5a6c9a05e55c ("drm: Fix FD ownership check in drm_master_check_perm()") 1c7a387ffef8 ("drm: Update file owner during use")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 5a6c9a05e55cb2972396cc991af9d74c8c15029a Mon Sep 17 00:00:00 2001 From: Lingkai Dong Lingkai.Dong@arm.com Date: Wed, 6 Dec 2023 13:51:58 +0000 Subject: [PATCH] drm: Fix FD ownership check in drm_master_check_perm() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit

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.dong@arm.com Reviewed-by: Christian König christian.koenig@amd.com Reviewed-by: Tvrtko Ursulin tvrtko.ursulin@intel.com Cc: stable@vger.kernel.org # v6.4+ Link: https://patchwork.freedesktop.org/patch/msgid/PA6PR08MB107665920BE9A96658CDA... Signed-off-by: Christian König christian.koenig@amd.com

diff --git a/drivers/gpu/drm/drm_auth.c b/drivers/gpu/drm/drm_auth.c index 2ed2585ded37..6899b3dc1f12 100644 --- a/drivers/gpu/drm/drm_auth.c +++ b/drivers/gpu/drm/drm_auth.c @@ -236,7 +236,7 @@ static int drm_master_check_perm(struct drm_device *dev, struct drm_file *file_priv) { if (file_priv->was_master && - rcu_access_pointer(file_priv->pid) == task_pid(current)) + rcu_access_pointer(file_priv->pid) == task_tgid(current)) return 0;

if (!capable(CAP_SYS_ADMIN))