CVE-2026-23150

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

nfc: llcp: Fix memleak in nfc_llcp_send_ui_frame().

syzbot reported various memory leaks related to NFC, struct

nfc_llcp_sock, sk_buff, nfc_dev, etc. [0]

The leading log hinted that nfc_llcp_send_ui_frame() failed

to allocate skb due to sock_error(sk) being -ENXIO.

ENXIO is set by nfc_llcp_socket_release() when struct

nfc_llcp_local is destroyed by local_cleanup().

The problem is that there is no synchronisation between

nfc_llcp_send_ui_frame() and local_cleanup(), and skb

could be put into local->tx_queue after it was purged in

local_cleanup():

CPU1 CPU2

---- ----

nfc_llcp_send_ui_frame() local_cleanup()

|- do { '

|- pdu = nfc_alloc_send_skb(..., &err)

| .

| |- nfc_llcp_socket_release(local, false, ENXIO);

| |- skb_queue_purge(&local->tx_queue); |

| ' |

|- skb_queue_tail(&local->tx_queue, pdu); |

... |

|- pdu = nfc_alloc_send_skb(..., &err) |

^._________________________________.'

local_cleanup() is called for struct nfc_llcp_local only

after nfc_llcp_remove_local() unlinks it from llcp_devices.

If we hold local->tx_queue.lock then, we can synchronise

the thread and nfc_llcp_send_ui_frame().

Let's do that and check list_empty(&local->list) before

queuing skb to local->tx_queue in nfc_llcp_send_ui_frame().

[0]:

[ 56.074943][ T6096] llcp: nfc_llcp_send_ui_frame: Could not allocate PDU (error=-6)

[ 64.318868][ T5813] kmemleak: 6 new suspected memory leaks (see /sys/kernel/debug/kmemleak)

BUG: memory leak

unreferenced object 0xffff8881272f6800 (size 1024):

comm "syz.0.17", pid 6096, jiffies 4294942766

hex dump (first 32 bytes):

00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................

27 00 03 40 00 00 00 00 00 00 00 00 00 00 00 00 '..@............

backtrace (crc da58d84d):

kmemleak_alloc_recursive include/linux/kmemleak.h:44 [inline]

slab_post_alloc_hook mm/slub.c:4979 [inline]

slab_alloc_node mm/slub.c:5284 [inline]

__do_kmalloc_node mm/slub.c:5645 [inline]

__kmalloc_noprof+0x3e3/0x6b0 mm/slub.c:5658

kmalloc_noprof include/linux/slab.h:961 [inline]

sk_prot_alloc+0x11a/0x1b0 net/core/sock.c:2239

sk_alloc+0x36/0x360 net/core/sock.c:2295

nfc_llcp_sock_alloc+0x37/0x130 net/nfc/llcp_sock.c:979

llcp_sock_create+0x71/0xd0 net/nfc/llcp_sock.c:1044

nfc_sock_create+0xc9/0xf0 net/nfc/af_nfc.c:31

__sock_create+0x1a9/0x340 net/socket.c:1605

sock_create net/socket.c:1663 [inline]

__sys_socket_create net/socket.c:1700 [inline]

__sys_socket+0xb9/0x1a0 net/socket.c:1747

__do_sys_socket net/socket.c:1761 [inline]

__se_sys_socket net/socket.c:1759 [inline]

__x64_sys_socket+0x1b/0x30 net/socket.c:1759

do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]

do_syscall_64+0xa4/0xfa0 arch/x86/entry/syscall_64.c:94

entry_SYSCALL_64_after_hwframe+0x77/0x7f

BUG: memory leak

unreferenced object 0xffff88810fbd9800 (size 240):

comm "syz.0.17", pid 6096, jiffies 4294942850

hex dump (first 32 bytes):

68 f0 ff 08 81 88 ff ff 68 f0 ff 08 81 88 ff ff h.......h.......

00 00 00 00 00 00 00 00 00 68 2f 27 81 88 ff ff .........h/'....

backtrace (crc 6cc652b1):

kmemleak_alloc_recursive include/linux/kmemleak.h:44 [inline]

slab_post_alloc_hook mm/slub.c:4979 [inline]

slab_alloc_node mm/slub.c:5284 [inline]

kmem_cache_alloc_node_noprof+0x36f/0x5e0 mm/slub.c:5336

__alloc_skb+0x203/0x240 net/core/skbuff.c:660

alloc_skb include/linux/skbuff.h:1383 [inline]

alloc_skb_with_frags+0x69/0x3f0 net/core/sk

---truncated---