drm/i915: Fix vm use-after-free in vma destruction
In vma destruction, the following race may occur: Thread 1: Thread 2: i915_vma_destroy(); ... list_del_init(vma->vm_link); ... mutex_unlock(vma->vm->mutex); __i915_vm_release(); release_references(); And in release_reference() we dereference vma->vm to get to the vm gt pointer, leading to a use-after free. However, __i915_vm_release() grabs the vm->mutex so the vm won't be destroyed before vma->vm->mutex is released, so extract the gt pointer under the vm->mutex to avoid the vma->vm dereference in release_references(). v2: Fix a typo in the commit message (Andi Shyti) Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/5944 Fixes: e1a7ab4f ("drm/i915: Remove the vm open count") Cc: Niranjana Vishwanathapura <niranjana.vishwanathapura@intel.com> Cc: Matthew Auld <matthew.auld@intel.com> Signed-off-by:Thomas Hellström <thomas.hellstrom@linux.intel.com> Acked-by:
Nirmoy Das <nirmoy.das@intel.con> Reviewed-by:
Andrzej Hajda <andrzej.hajda@intel.com> Reviewed-by:
Matthew Auld <matthew.auld@intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20220620123659.381772-1-thomas.hellstrom@linux.intel.com
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