Re: [PATCH] drm/xe/tracing: Fix a potential TP_printk UAF

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 noticed that xe_mem_type_to_name is not static, it likely should be. Would that help here?

Matt

•       __get_str(old_placement_name),
  

•       __get_str(new_placement_name), __get_str(device_id))
  

); DECLARE_EVENT_CLASS(xe_vma, -- 2.47.1