On Mon, 2024-12-23 at 07:44 -0800, Matthew Brost wrote:
On Mon, Dec 23, 2024 at 02:42:50PM +0100, Thomas Hellström wrote:
The commit afd2627f727b ("tracing: Check "%s" dereference via the field and not the TP_printk format") exposes potential UAFs in the xe_bo_move trace event.
Fix those by avoiding dereferencing the xe_mem_type_to_name[] array at TP_printk time.
Since some code refactoring has taken place, explicit backporting may be needed for kernels older than 6.10.
Fixes: e46d3f813abd ("drm/xe/trace: Extract bo, vm, vma traces") Cc: Gustavo Sousa gustavo.sousa@intel.com Cc: Lucas De Marchi lucas.demarchi@intel.com Cc: Radhakrishna Sripada radhakrishna.sripada@intel.com Cc: Matt Roper matthew.d.roper@intel.com Cc: "Thomas Hellström" thomas.hellstrom@linux.intel.com Cc: Rodrigo Vivi rodrigo.vivi@intel.com Cc: intel-xe@lists.freedesktop.org Cc: stable@vger.kernel.org # v6.11+ Signed-off-by: Thomas Hellström thomas.hellstrom@linux.intel.com
drivers/gpu/drm/xe/xe_trace_bo.h | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-)
diff --git a/drivers/gpu/drm/xe/xe_trace_bo.h b/drivers/gpu/drm/xe/xe_trace_bo.h index 1762dd30ba6d..ea50fee50c7d 100644 --- a/drivers/gpu/drm/xe/xe_trace_bo.h +++ b/drivers/gpu/drm/xe/xe_trace_bo.h @@ -60,8 +60,8 @@ TRACE_EVENT(xe_bo_move, TP_STRUCT__entry( __field(struct xe_bo *, bo) __field(size_t, size)
__field(u32, new_placement)__field(u32, old_placement)
__string(new_placement_name,xe_mem_type_to_name[new_placement])
__string(old_placement_name,xe_mem_type_to_name[old_placement]) __string(device_id, __dev_name_bo(bo)) __field(bool, move_lacks_source) ), @@ -69,15 +69,15 @@ TRACE_EVENT(xe_bo_move, TP_fast_assign( __entry->bo = bo; __entry->size = bo->size;
__entry->new_placement = new_placement;__entry->old_placement = old_placement;
__assign_str(new_placement_name);__assign_str(old_placement_name);__assign_str(device_id); __entry->move_lacks_source = move_lacks_source; ), TP_printk("move_lacks_source:%s, migrate object %p [size %zu] from %s to %s device_id:%s", __entry->move_lacks_source ? "yes" : "no", __entry->bo, __entry->size,
xe_mem_type_to_name[__entry->old_placement],xe_mem_type_to_name[__entry->new_placement],__get_str(device_id))
So is this the UAF? i.e., The Xe module unloads and xe_mem_type_to_name is gone?
I would imagine that's the intention of the warning. However removing the xe_module seems to empty the trace buffer of xe_bo_move events. Whether there is a race in that process or whether the TP_printk check can't distinguish between module local addresses and other addresses is hard to tell. In any case, it looks like we need to comply with the warning here (I suspect CI refuses to run otherwise), and since it only appears to trigger on the xe module load on my system, it's unlikely that mentioned commit will be reverted.
I noticed that xe_mem_type_to_name is not static, it likely should be. Would that help here?
No, doesn't help unfortunately.
/Thomas
Matt
__get_str(old_placement_name),__get_str(new_placement_name),__get_str(device_id)) ); DECLARE_EVENT_CLASS(xe_vma, -- 2.47.1