From: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx> 3.12-stable review patch. If anyone has any objections, please let me know. =============== commit 5351fbb1bf1413f6024892093528280769ca852f upstream. page_flip_completed() dereferences 'work' variable after executing queue_work(). This is not safe as the 'work' item might be already freed by queued work: BUG: KASAN: use-after-free in page_flip_completed+0x3ff/0x490 at addr ffff8803dc010f90 Call Trace: __asan_report_load8_noabort+0x59/0x80 page_flip_completed+0x3ff/0x490 intel_finish_page_flip_mmio+0xe3/0x130 intel_pipe_handle_vblank+0x2d/0x40 gen8_irq_handler+0x4a7/0xed0 __handle_irq_event_percpu+0xf6/0x860 handle_irq_event_percpu+0x6b/0x160 handle_irq_event+0xc7/0x1b0 handle_edge_irq+0x1f4/0xa50 handle_irq+0x41/0x70 do_IRQ+0x9a/0x200 common_interrupt+0x89/0x89 Freed: kfree+0x113/0x4d0 intel_unpin_work_fn+0x29a/0x3b0 process_one_work+0x79e/0x1b70 worker_thread+0x611/0x1460 kthread+0x241/0x3a0 ret_from_fork+0x27/0x40 Move queue_work() after trace_i915_flip_complete() to fix this. Fixes: e5510fac98a7 ("drm/i915: add tracepoints for flip requests & completions") Signed-off-by: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx> Reviewed-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> Signed-off-by: Daniel Vetter <daniel.vetter@xxxxxxxx> Link: http://patchwork.freedesktop.org/patch/msgid/20170126143211.24013-1-aryabinin@xxxxxxxxxxxxx (cherry picked from commit 05c41f926fcc7ef838c80a6a99d84f67b4e0b824) Signed-off-by: Jani Nikula <jani.nikula@xxxxxxxxx> Signed-off-by: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx> Signed-off-by: Jiri Slaby <jslaby@xxxxxxx> --- drivers/gpu/drm/i915/intel_display.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c index 57d5abc420d1..bfb054d1d5b0 100644 --- a/drivers/gpu/drm/i915/intel_display.c +++ b/drivers/gpu/drm/i915/intel_display.c @@ -7696,9 +7696,9 @@ static void do_intel_finish_page_flip(struct drm_device *dev, wake_up_all(&dev_priv->pending_flip_queue); - queue_work(dev_priv->wq, &work->work); - trace_i915_flip_complete(intel_crtc->plane, work->pending_flip_obj); + + queue_work(dev_priv->wq, &work->work); } void intel_finish_page_flip(struct drm_device *dev, int pipe) -- 2.12.0