Description: vfio/mdev: Fix a null-ptr-deref bug for mdev_unregister_parent()
References:
Notes:
 carnil> Introduced in da44c340c4fe ("vfio/mdev: simplify mdev_type handling").
 carnil> Vulnerable versions: 6.1-rc1.
Bugs:
upstream: released (6.6-rc4) [c777b11d34e0f47dbbc4b018ef65ad030f2b283a]
6.7-upstream-stable: N/A "Fixed before branching point"
6.6-upstream-stable: N/A "Fixed before branching point"
6.1-upstream-stable: released (6.1.56) [c01b2e0ee22ef8b4dd7509a93aecc0ac0826bae4]
5.10-upstream-stable: N/A "Vulnerable code not present"
4.19-upstream-stable: N/A "Vulnerable code not present"
sid: released (6.5.6-1)
6.1-bookworm-security: released (6.1.64-1)
5.10-bullseye-security: N/A "Vulnerable code not present"
4.19-buster-security: N/A "Vulnerable code not present"