[PATCH AUTOSEL 6.18] drm/xe: Fix null pointer dereference in devcoredump cleanup

[Sasha Levin <sashal@kernel.org>]

From: Zhanjun Dong <zhanjun.dong@intel.com>

[ Upstream commit 12ef528d78adc8ea4e7e3db594f3bcac327e79fa ]

In xe_devcoredump_snapshot_free(), ss->gt may be NULL when the snapshot
was never fully populated (e.g., when cleanup is triggered without a
prior capture). Guard the xe_guc_capture_put_matched_nodes() call with
IS_ERR_OR_NULL() to prevent a null dereference.

In xe_devcoredump_free(), the deferred work is only queued when a
coredump is captured, so guard cancel_work_sync() with a check on
coredump->captured.

Signed-off-by: Zhanjun Dong <zhanjun.dong@intel.com>
Reviewed-by: Vinay Belgaumkar <vinay.belgaumkar@intel.com>
Signed-off-by: Vinay Belgaumkar <vinay.belgaumkar@intel.com>
Link: https://patch.msgid.link/20260326181017.2060209-1-zhanjun.dong@intel.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---

LLM Generated explanations, may be completely bogus:

The follow-up check completed: `git log` found no commits matching the
fix (`IS_ERR_OR_NULL(ss->gt)` or "devcoredump cleanup"), so it isn’t in
this tree yet. That matches the earlier read of `xe_devcoredump.c` — the
unconditional dereference and `cancel_work_sync()` are still there.
Backport recommendation remains **YES** for v6.18.43.

 drivers/gpu/drm/xe/xe_devcoredump.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/xe/xe_devcoredump.c b/drivers/gpu/drm/xe/xe_devcoredump.c
index 203e3038cc817..26a294f79e79f 100644
--- a/drivers/gpu/drm/xe/xe_devcoredump.c
+++ b/drivers/gpu/drm/xe/xe_devcoredump.c
@@ -150,7 +150,8 @@ static void xe_devcoredump_snapshot_free(struct xe_devcoredump_snapshot *ss)
 	xe_guc_ct_snapshot_free(ss->guc.ct);
 	ss->guc.ct = NULL;
 
-	xe_guc_capture_put_matched_nodes(&ss->gt->uc.guc);
+	if (!IS_ERR_OR_NULL(ss->gt))
+		xe_guc_capture_put_matched_nodes(&ss->gt->uc.guc);
 	ss->matched_node = NULL;
 
 	xe_guc_exec_queue_snapshot_free(ss->ge);
@@ -255,7 +256,8 @@ static void xe_devcoredump_free(void *data)
 	if (!data || !coredump_to_xe(coredump))
 		return;
 
-	cancel_work_sync(&coredump->snapshot.work);
+	if (coredump->captured)
+		cancel_work_sync(&coredump->snapshot.work);
 
 	mutex_lock(&coredump->lock);
 
-- 
2.53.0