The patch below does not apply to the 6.8-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-6.8.y git checkout FETCH_HEAD git cherry-pick -x 98957360563e7ffdc0c2b3a314655eff8bc1cb5a # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2024051321-bonehead-slang-4a7c@gregkh' --subject-prefix 'PATCH 6.8.y' HEAD^..

Possible dependencies:

98957360563e ("drm/xe/vm: prevent UAF in rebind_work_func()") 0eb2a18a8fad ("drm/xe: Implement VM snapshot support for BO's and userptr") be7d51c5b468 ("drm/xe: Add batch buffer addresses to devcoredump") 4376cee62092 ("drm/xe: Print more device information in devcoredump") 98fefec8c381 ("drm/xe: Change devcoredump functions parameters to xe_sched_job")

thanks,

greg k-h

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

From 98957360563e7ffdc0c2b3a314655eff8bc1cb5a Mon Sep 17 00:00:00 2001 From: Matthew Auld matthew.auld@intel.com Date: Tue, 23 Apr 2024 08:47:23 +0100 Subject: [PATCH] drm/xe/vm: prevent UAF in rebind_work_func()

We flush the rebind worker during the vm close phase, however in places like preempt_fence_work_func() we seem to queue the rebind worker without first checking if the vm has already been closed. The concern here is the vm being closed with the worker flushed, but then being rearmed later, which looks like potential uaf, since there is no actual refcounting to track the queued worker. We can't take the vm->lock here in preempt_rebind_work_func() to first check if the vm is closed since that will deadlock, so instead flush the worker again when the vm refcount reaches zero.

v2: - Grabbing vm->lock in the preempt worker creates a deadlock, so checking the closed state is tricky. Instead flush the worker when the refcount reaches zero. It should be impossible to queue the preempt worker without already holding vm ref.

Fixes: dd08ebf6c352 ("drm/xe: Introduce a new DRM driver for Intel GPUs") Closes: https://gitlab.freedesktop.org/drm/xe/kernel/-/issues/1676 Closes: https://gitlab.freedesktop.org/drm/xe/kernel/-/issues/1591 Closes: https://gitlab.freedesktop.org/drm/xe/kernel/-/issues/1364 Closes: https://gitlab.freedesktop.org/drm/xe/kernel/-/issues/1304 Closes: https://gitlab.freedesktop.org/drm/xe/kernel/-/issues/1249 Signed-off-by: Matthew Auld matthew.auld@intel.com Cc: Matthew Brost matthew.brost@intel.com Cc: stable@vger.kernel.org # v6.8+ Reviewed-by: Matthew Brost matthew.brost@intel.com Link: https://patchwork.freedesktop.org/patch/msgid/20240423074721.119633-4-matthe... (cherry picked from commit 3d44d67c441a9fe6f81a1d705f7de009a32a5b35) Signed-off-by: Lucas De Marchi lucas.demarchi@intel.com

diff --git a/drivers/gpu/drm/xe/xe_vm.c b/drivers/gpu/drm/xe/xe_vm.c index 3d4c8f342e21..32cd0c978aa2 100644 --- a/drivers/gpu/drm/xe/xe_vm.c +++ b/drivers/gpu/drm/xe/xe_vm.c @@ -1606,6 +1606,9 @@ static void vm_destroy_work_func(struct work_struct *w) /* xe_vm_close_and_put was not called? */ xe_assert(xe, !vm->size);

+ if (xe_vm_in_preempt_fence_mode(vm)) + flush_work(&vm->preempt.rebind_work); + mutex_destroy(&vm->snap_mutex);

if (!(vm->flags & XE_VM_FLAG_MIGRATION))