On Thu, Jan 26, 2017 at 05:32:11PM +0300, Andrey Ryabinin wrote:
> 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>
That's old, and indeed does seem to be present from that commit and not
exposed by something later.
Cc: <stable@xxxxxxxxxxxxxxx> # v2.6.36+
Reviewed-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
-Chris
--
Chris Wilson, Intel Open Source Technology Centre
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