From 7057a8f126f14f14b040faecfa220fd27c6c2f85 Mon Sep 17 00:00:00 2001
From: Rob Clark <robdclark@chromium.org>
Date: Fri, 27 Jan 2023 12:05:31 -0800
Subject: [PATCH] drm/i915: Fix potential bit_17 double-free
Git-commit: 7057a8f126f14f14b040faecfa220fd27c6c2f85
Patch-mainline: v6.2-rc7
Alt-commit: 10e0cbaaf1104f449d695c80bcacf930dcd3c42e
References: git-fixes
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 <robdclark@chromium.org>
Fixes: 2850748ef876 ("drm/i915: Pull i915_vma_pin under the vm->mutex")
Cc: <stable@vger.kernel.org> # v5.5+
[tursulin: Correct fixes tag and added cc stable.]
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230127200550.3531984-1-robdclark@gmail.com
(cherry picked from commit 10e0cbaaf1104f449d695c80bcacf930dcd3c42e)
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Acked-by: Takashi Iwai <tiwai@suse.de>
---
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 fd42b89b7162..bc21b1c2350a 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;
}
--
2.35.3