CVE-2026-45966

In the Linux kernel, the following vulnerability has been resolved:

apparmor: fix NULL pointer dereference in __unixneedsrevalidation

When receiving file descriptors via SCM_RIGHTS, both the socket pointer and the socket's sk pointer can be NULL during socket setup or teardown, causing NULL pointer dereferences in __unixneedsrevalidation().

This is a regression in AppArmor 5.0.0 (kernel 6.17+) where the new __unixneedsrevalidation() function was added without proper NULL checks.

The crash manifests as: BUG: kernel NULL pointer dereference, address: 0x0000000000000018 RIP: aafileperm+0xb7/0x3b0 (or +0xbe/0x3b0, +0xc0/0x3e0) Call Trace: apparmorfilereceive+0x42/0x80 securityfilereceive+0x2e/0x50 receivefd+0x1d/0xf0 scmdetach_fds+0xad/0x1c0

The function dereferences sock->sk->sk_family without checking if either sock or sock->sk is NULL first.

Add NULL checks for both sock and sock->sk before accessing sk_family.