In the Linux kernel, the following vulnerability has been resolved:
iommufd: Avoid locking internal accesses during unmap
iommufd_access_notify_unmap() skips internal accesses because they do
not have an external unmap callback to invoke. However, the current test calls iommufd_lock_obj() before checking
whether the access is internal. If iommufd_lock_obj() succeeds, the loop
then sees the internal access and continues, bypassing the matching
iommufd_put_object() used by the normal unmap path.
This leaks the
object reference taken by iommufd_lock_obj(). Check for internal accesses first so skipped entries are never locked.
References 3
https://git.kernel.org/stable/c/0dbcdf4473a614adbd732d567c9b39ac0e040e0c
416baaa9-dc9f-4396-8d5f-8c081fb06d67
https://git.kernel.org/stable/c/436189ee4bb2c7c993b945d68570dd38c3e4349e
416baaa9-dc9f-4396-8d5f-8c081fb06d67
https://git.kernel.org/stable/c/50a66a63d1c841ae6b28a4551f642c1bba4c9529
416baaa9-dc9f-4396-8d5f-8c081fb06d67