CVE-2026-45966apparmor: fix NULL pointer dereference in __unix_needs_revalidation

Official description

In the Linux kernel, the following vulnerability has been resolved: apparmor: fix NULL pointer dereference in __unix_needs_revalidation 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 __unix_needs_revalidation(). This is a regression in AppArmor 5.0.0 (kernel 6.17+) where the new __unix_needs_revalidation() function was added without proper NULL checks. The crash manifests as: BUG: kernel NULL pointer dereference, address: 0x0000000000000018 RIP: aa_file_perm+0xb7/0x3b0 (or +0xbe/0x3b0, +0xc0/0x3e0) Call Trace: apparmor_file_receive+0x42/0x80 security_file_receive+0x2e/0x50 receive_fd+0x1d/0xf0 scm_detach_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.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/fea017a7f6abe179decf575a2d8464c74edb3964
• https://git.kernel.org/stable/c/e85bc9101afc4202aa2269967ce9d3ffbecd0994
• https://git.kernel.org/stable/c/e2938ad00b21340c0362562dfedd7cfec0554d67