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drm/xe/pt: Fix NULL pointer dereference in xe_pt_zap_ptes_entry()

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The page-table walk framework may pass a NULL *child pointer for
unpopulated entries. xe_pt_zap_ptes_entry() called container_of(*child)
before checking for NULL, then dereferenced the result, causing a crash.

Move the container_of() call after a NULL guard, so the function returns
early instead of proceeding with an invalid pointer. XE_WARN_ON is kept
to help root cause the issue, but we now bail instead of crashing the
driver.

v2: Comment that triggering XE_WARN_ON is unexpected behavior (Matt Brost)

Fixes: dd08ebf6c3 ("drm/xe: Introduce a new DRM driver for Intel GPUs")
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Reviewed-by: Matthew Brost <matthew.brost@intel.com>
Link: https://lore.kernel.org/r/20260616081756.286918-1-francois.dugast@intel.com
Signed-off-by: Francois Dugast <francois.dugast@intel.com>
(cherry picked from commit b9297d19d9df5d4b6c994648570c5dcd1cac68ff)
Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
This commit is contained in:
Francois Dugast 2026-06-16 10:17:56 +02:00 committed by Thomas Hellström
parent d42df9dce7
commit 3feeb66719
1 changed files with 10 additions and 2 deletions
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12
drivers/gpu/drm/xe/xe_pt.c
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@ -885,12 +885,20 @@ static int xe_pt_zap_ptes_entry(struct xe_ptw *parent, pgoff_t offset,
{
struct xe_pt_zap_ptes_walk *xe_walk =
container_of(walk, typeof(*xe_walk), base);
struct xe_pt *xe_child = container_of(*child, typeof(*xe_child), base);
struct xe_pt *xe_child;
pgoff_t end_offset;
XE_WARN_ON(!*child);
XE_WARN_ON(!level);
/*
* Below would be unexpected behavior that needs to be root caused
* but better warn and bail than crash the driver.
*/
if (XE_WARN_ON(!*child))
return 0;
xe_child = container_of(*child, typeof(*xe_child), base);
/*
* Note that we're called from an entry callback, and we're dealing
* with the child of that entry rather than the parent, so need to