2021-08-18 14:54:34

by Tim Gardner

[permalink] [raw]
Subject: [PATCH] drm/i915/gem: Avoid NULL dereference in __i915_gem_object_lock()

Coverity warns of a possible NULL dereference:

Both dma_resv_lock_interruptible() and dma_resv_lock() can return -EDEADLK. Protect
against a NULL dereference by checking for NULL before saving the object pointer. This
is consistent with previous checks for ww==NULL.

Addresses-Coverity: ("Dereference after null check")

Cc: [email protected]
Fixes: 80f0b679d6f0683f23cf98a511af3e44dd509472 ("drm/i915: Add an implementation for i915_gem_ww_ctx locking, v2.")
Cc: [email protected]
Cc: Maarten Lankhorst <[email protected]>
Cc: Jani Nikula <[email protected]>
Cc: Joonas Lahtinen <[email protected]>
Cc: Rodrigo Vivi <[email protected]>
Cc: David Airlie <[email protected]>
Cc: Daniel Vetter <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Signed-off-by: Tim Gardner <[email protected]>
---
drivers/gpu/drm/i915/gem/i915_gem_object.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_object.h b/drivers/gpu/drm/i915/gem/i915_gem_object.h
index 48112b9d76df..3391ca4f662a 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_object.h
+++ b/drivers/gpu/drm/i915/gem/i915_gem_object.h
@@ -187,7 +187,7 @@ static inline int __i915_gem_object_lock(struct drm_i915_gem_object *obj,
if (ret == -EALREADY)
ret = 0;

- if (ret == -EDEADLK) {
+ if (ret == -EDEADLK && ww) {
i915_gem_object_get(obj);
ww->contended = obj;
}
--
2.33.0