Patch "drm/xe/guc_submit: add missing locking in wedged_fini" has been added to the 6.11-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    drm/xe/guc_submit: add missing locking in wedged_fini

to the 6.11-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     drm-xe-guc_submit-add-missing-locking-in-wedged_fini.patch
and it can be found in the queue-6.11 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 703306b2019445a8e36aca5c794865f660656bb2
Author: Matthew Auld <matthew.auld@xxxxxxxxx>
Date:   Tue Sep 24 16:09:48 2024 +0100

    drm/xe/guc_submit: add missing locking in wedged_fini
    
    [ Upstream commit 790533e44bfc7af929842fccd9674c9f424d4627 ]
    
    Any non-wedged queue can have a zero refcount here and can be running
    concurrently with an async queue destroy, therefore dereferencing the
    queue ptr to check wedge status after the lookup can trigger UAF if
    queue is not wedged.  Fix this by keeping the submission_state lock held
    around the check to postpone the free and make the check safe, before
    dropping again around the put() to avoid the deadlock.
    
    Fixes: 8ed9aaae39f3 ("drm/xe: Force wedged state and block GT reset upon any GPU hang")
    Signed-off-by: Matthew Auld <matthew.auld@xxxxxxxxx>
    Cc: Matthew Brost <matthew.brost@xxxxxxxxx>
    Reviewed-by: Matthew Brost <matthew.brost@xxxxxxxxx>
    Link: https://patchwork.freedesktop.org/patch/msgid/20240924150947.118433-2-matthew.auld@xxxxxxxxx
    (cherry picked from commit d28af0b6b9580b9f90c265a7da0315b0ad20bbfd)
    Signed-off-by: Lucas De Marchi <lucas.demarchi@xxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/gpu/drm/xe/xe_guc_submit.c b/drivers/gpu/drm/xe/xe_guc_submit.c
index 59b36c7998c24..3d91734980110 100644
--- a/drivers/gpu/drm/xe/xe_guc_submit.c
+++ b/drivers/gpu/drm/xe/xe_guc_submit.c
@@ -290,9 +290,15 @@ static void guc_submit_wedged_fini(void *arg)
 	struct xe_exec_queue *q;
 	unsigned long index;
 
-	xa_for_each(&guc->submission_state.exec_queue_lookup, index, q)
-		if (exec_queue_wedged(q))
+	mutex_lock(&guc->submission_state.lock);
+	xa_for_each(&guc->submission_state.exec_queue_lookup, index, q) {
+		if (exec_queue_wedged(q)) {
+			mutex_unlock(&guc->submission_state.lock);
 			xe_exec_queue_put(q);
+			mutex_lock(&guc->submission_state.lock);
+		}
+	}
+	mutex_unlock(&guc->submission_state.lock);
 }
 
 static const struct xe_exec_queue_ops guc_exec_queue_ops;