CVE-2026-53033

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

bpf, sockmap: Take state lock for af_unix iter

When a BPF iterator program updates a sockmap, there is a race condition in

unix_stream_bpf_update_proto() where the `peer` pointer can become stale[1]

during a state transition TCP_ESTABLISHED -> TCP_CLOSE.

CPU0 bpf CPU1 close

-------- ----------

// unix_stream_bpf_update_proto()

sk_pair = unix_peer(sk)

if (unlikely(!sk_pair))

return -EINVAL;

// unix_release_sock()

skpair = unix_peer(sk);

unix_peer(sk) = NULL;

sock_put(skpair)

sock_hold(sk_pair) // UaF

More practically, this fix guarantees that the iterator program is

consistently provided with a unix socket that remains stable during

iterator execution.

[1]:

BUG: KASAN: slab-use-after-free in unix_stream_bpf_update_proto+0x155/0x490

Write of size 4 at addr ffff8881178c9a00 by task test_progs/2231

Call Trace:

dump_stack_lvl+0x5d/0x80

print_report+0x170/0x4f3

kasan_report+0xe4/0x1c0

kasan_check_range+0x125/0x200

unix_stream_bpf_update_proto+0x155/0x490

sock_map_link+0x71c/0xec0

sock_map_update_common+0xbc/0x600

sock_map_update_elem+0x19a/0x1f0

bpf_prog_bbbf56096cdd4f01_selective_dump_unix+0x20c/0x217

bpf_iter_run_prog+0x21e/0xae0

bpf_iter_unix_seq_show+0x1e0/0x2a0

bpf_seq_read+0x42c/0x10d0

vfs_read+0x171/0xb20

ksys_read+0xff/0x200

do_syscall_64+0xf7/0x5e0

entry_SYSCALL_64_after_hwframe+0x76/0x7e

Allocated by task 2236:

kasan_save_stack+0x30/0x50

kasan_save_track+0x14/0x30

__kasan_slab_alloc+0x63/0x80

kmem_cache_alloc_noprof+0x1d5/0x680

sk_prot_alloc+0x59/0x210

sk_alloc+0x34/0x470

unix_create1+0x86/0x8a0

unix_stream_connect+0x318/0x15b0

__sys_connect+0xfd/0x130

__x64_sys_connect+0x72/0xd0

do_syscall_64+0xf7/0x5e0

entry_SYSCALL_64_after_hwframe+0x76/0x7e

Freed by task 2236:

kasan_save_stack+0x30/0x50

kasan_save_track+0x14/0x30

kasan_save_free_info+0x3b/0x70

__kasan_slab_free+0x47/0x70

kmem_cache_free+0x11c/0x590

__sk_destruct+0x432/0x6e0

unix_release_sock+0x9b3/0xf60

unix_release+0x8a/0xf0

__sock_release+0xb0/0x270

sock_close+0x18/0x20

__fput+0x36e/0xac0

fput_close_sync+0xe5/0x1a0

__x64_sys_close+0x7d/0xd0

do_syscall_64+0xf7/0x5e0

entry_SYSCALL_64_after_hwframe+0x76/0x7e