From 10e0cbaaf1104f449d695c80bcacf930dcd3c42e Mon Sep 17 00:00:00 2001 From: Rob Clark Date: Fri, 27 Jan 2023 12:05:31 -0800 Subject: [PATCH] drm/i915: Fix potential bit_17 double-free A userspace with multiple threads racing I915_GEM_SET_TILING to set the tiling to I915_TILING_NONE could trigger a double free of the bit_17 bitmask. (Or conversely leak memory on the transition to tiled.) Move allocation/free'ing of the bitmask within the section protected by the obj lock. Signed-off-by: Rob Clark Fixes: 2850748ef876 ("drm/i915: Pull i915_vma_pin under the vm->mutex") Cc: # v5.5+ [tursulin: Correct fixes tag and added cc stable.] Reviewed-by: Tvrtko Ursulin Signed-off-by: Tvrtko Ursulin Link: https://patchwork.freedesktop.org/patch/msgid/20230127200550.3531984-1-robdclark@gmail.com --- drivers/gpu/drm/i915/gem/i915_gem_tiling.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/drivers/gpu/drm/i915/gem/i915_gem_tiling.c b/drivers/gpu/drm/i915/gem/i915_gem_tiling.c index 04bb909..a049ca0 100644 --- a/drivers/gpu/drm/i915/gem/i915_gem_tiling.c +++ b/drivers/gpu/drm/i915/gem/i915_gem_tiling.c @@ -305,10 +305,6 @@ i915_gem_object_set_tiling(struct drm_i915_gem_object *obj, spin_unlock(&obj->vma.lock); obj->tiling_and_stride = tiling | stride; - i915_gem_object_unlock(obj); - - /* Force the fence to be reacquired for GTT access */ - i915_gem_object_release_mmap_gtt(obj); /* Try to preallocate memory required to save swizzling on put-pages */ if (i915_gem_object_needs_bit17_swizzle(obj)) { @@ -321,6 +317,11 @@ i915_gem_object_set_tiling(struct drm_i915_gem_object *obj, obj->bit_17 = NULL; } + i915_gem_object_unlock(obj); + + /* Force the fence to be reacquired for GTT access */ + i915_gem_object_release_mmap_gtt(obj); + return 0; } -- 2.7.4