Hi,

On 10/12/21 15:25, Colin King wrote:

From: Colin Ian King colin.king@canonical.com

The assignment of pointer backup_bo dereferences pointer backup before backup is null checked, this could lead to a null pointer dereference issue. Fix this by only assigning backup_bo after backup has been null checked.

Addresses-Coverity: ("Dereference before null check") Fixes: c56ce9565374 ("drm/i915 Implement LMEM backup and restore for suspend / resume") Signed-off-by: Colin Ian King colin.king@canonical.com

There's not really a pointer dereference here, just pointer arithmetics, so the code should be safe (but admittedly fragile), so to keep Coverity happy,

Reviewed-by: Thomas Hellström thomas.hellstrom@linux.intel.com

---

drivers/gpu/drm/i915/gem/i915_gem_ttm_pm.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_ttm_pm.c b/drivers/gpu/drm/i915/gem/i915_gem_ttm_pm.c index 3b6d14b5c604..4ec6c557083a 100644 --- a/drivers/gpu/drm/i915/gem/i915_gem_ttm_pm.c +++ b/drivers/gpu/drm/i915/gem/i915_gem_ttm_pm.c @@ -149,7 +149,7 @@ static int i915_ttm_restore(struct i915_gem_apply_to_region *apply, struct i915_gem_ttm_pm_apply *pm_apply = container_of(apply, typeof(*pm_apply), base); struct drm_i915_gem_object *backup = obj->ttm.backup;

• struct ttm_buffer_object *backup_bo = i915_gem_to_ttm(backup);

• struct ttm_buffer_object *backup_bo; struct ttm_operation_ctx ctx = {}; int err;

@@ -163,6 +163,8 @@ static int i915_ttm_restore(struct i915_gem_apply_to_region *apply, if (err) return err;

• backup_bo = i915_gem_to_ttm(backup);
• /* Content may have been swapped. */ err = ttm_tt_populate(backup_bo->bdev, backup_bo->ttm, &ctx); if (!err) {