| From | Greg Kroah-Hartman <> | Subject | [PATCH 3.14 064/140] drm/i915: Do not dereference pointers from ring buffer in evict event | Date | Wed, 28 May 2014 21:33:23 -0700 |
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3.14-stable review patch. If anyone has any objections, please let me know.
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From: Steven Rostedt <rostedt@goodmis.org>
commit 9297ebf29ad9118edd6c0fedc84f03e35028827d upstream.
The TP_printk() should never dereference any pointers, because the ring buffer can be read at some unknown time in the future. If a device no longer exists, it can cause a kernel oops. This also makes this event useless when saving the ring buffer in userspaces tools such as perf and trace-cmd.
The i915_gem_evict_vm dereferences the vm pointer which may also not exist when the ring buffer is read sometime in the future.
Link: http://lkml.kernel.org/r/1395095198-20034-3-git-send-email-artagnon@gmail.com Reported-by: Ramkumar Ramachandra <artagnon@gmail.com> Fixes: bcccff847d1f "drm/i915: trace vm eviction instead of everything" Signed-off-by: Steven Rostedt <rostedt@goodmis.org> [danvet: Try to make it actually compile] Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- drivers/gpu/drm/i915/i915_trace.h | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
--- a/drivers/gpu/drm/i915/i915_trace.h +++ b/drivers/gpu/drm/i915/i915_trace.h @@ -238,14 +238,16 @@ TRACE_EVENT(i915_gem_evict_vm, TP_ARGS(vm), TP_STRUCT__entry( + __field(u32, dev) __field(struct i915_address_space *, vm) ), TP_fast_assign( + __entry->dev = vm->dev->primary->index; __entry->vm = vm; ), - TP_printk("dev=%d, vm=%p", __entry->vm->dev->primary->index, __entry->vm) + TP_printk("dev=%d, vm=%p", __entry->dev, __entry->vm) ); TRACE_EVENT(i915_gem_ring_sync_to,
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