From 5351fbb1bf1413f6024892093528280769ca852f Mon Sep 17 00:00:00 2001 From: Andrey Ryabinin Date: Thu, 26 Jan 2017 17:32:11 +0300 Subject: [PATCH] drm/i915: fix use-after-free in page_flip_completed() 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 Cc: # v2.6.36+ Reviewed-by: Chris Wilson Signed-off-by: Daniel Vetter Link: http://patchwork.freedesktop.org/patch/msgid/20170126143211.24013-1-aryabinin@virtuozzo.com (cherry picked from commit 05c41f926fcc7ef838c80a6a99d84f67b4e0b824) Signed-off-by: Jani Nikula --- 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 f1e4a21d4664..891c86aef99d 100644 --- a/drivers/gpu/drm/i915/intel_display.c +++ b/drivers/gpu/drm/i915/intel_display.c @@ -4262,10 +4262,10 @@ static void page_flip_completed(struct intel_crtc *intel_crtc) drm_crtc_vblank_put(&intel_crtc->base); wake_up_all(&dev_priv->pending_flip_queue); - queue_work(dev_priv->wq, &work->unpin_work); - trace_i915_flip_complete(intel_crtc->plane, work->pending_flip_obj); + + queue_work(dev_priv->wq, &work->unpin_work); } static int intel_crtc_wait_for_pending_flips(struct drm_crtc *crtc) -- 2.20.1