linux.git/net/nfc/llcp_core.c, branch master

nfc: llcp: Fix use-after-free race in nfc_llcp_recv_cc()

2026-05-05T09:37:11Z

A race condition exists in the NFC LLCP connection state machine where the connection acceptance packet (CC) can be processed concurrently with socket release. This can lead to a use-after-free of the socket object. When nfc_llcp_recv_cc() moves the socket from the connecting_sockets list to the sockets list, it does so without holding the socket lock. If llcp_sock_release() is executing concurrently, it might have already unlinked the socket and dropped its references, which can result in nfc_llcp_recv_cc() linking a freed socket into the live list. Fix this by holding lock_sock() during the state transition and list movement in nfc_llcp_recv_cc(). After acquiring the lock, check if the socket is still hashed to ensure it hasn't already been unlinked and marked for destruction by the release path. This aligns the locking pattern with recv_hdlc() and recv_disc(). Fixes: a69f32af86e3 ("NFC: Socket linked list") Signed-off-by: Lee Jones Reviewed-by: Simon Horman Link: https://patch.msgid.link/20260429134115.3558604-2-lee@kernel.org Signed-off-by: David Heidelberg

nfc: llcp: add missing return after LLCP_CLOSED checks

2026-04-12T18:12:44Z

In nfc_llcp_recv_hdlc() and nfc_llcp_recv_disc(), when the socket state is LLCP_CLOSED, the code correctly calls release_sock() and nfc_llcp_sock_put() but fails to return. Execution falls through to the remainder of the function, which calls release_sock() and nfc_llcp_sock_put() again. This results in a double release_sock() and a refcount underflow via double nfc_llcp_sock_put(), leading to a use-after-free. Add the missing return statements after the LLCP_CLOSED branches in both functions to prevent the fall-through. Fixes: d646960f7986 ("NFC: Initial LLCP support") Signed-off-by: Junxi Qian Reviewed-by: Eric Dumazet Link: https://patch.msgid.link/20260408081006.3723-1-qjx1298677004@gmail.com Signed-off-by: Jakub Kicinski

Convert 'alloc_obj' family to use the new default GFP_KERNEL argument

2026-02-22T01:09:51Z

This was done entirely with mindless brute force, using git grep -l '\

treewide: Replace kmalloc with kmalloc_obj for non-scalar types

2026-02-21T09:02:28Z

This is the result of running the Coccinelle script from scripts/coccinelle/api/kmalloc_objs.cocci. The script is designed to avoid scalar types (which need careful case-by-case checking), and instead replace kmalloc-family calls that allocate struct or union object instances: Single allocations: kmalloc(sizeof(TYPE), ...) are replaced with: kmalloc_obj(TYPE, ...) Array allocations: kmalloc_array(COUNT, sizeof(TYPE), ...) are replaced with: kmalloc_objs(TYPE, COUNT, ...) Flex array allocations: kmalloc(struct_size(PTR, FAM, COUNT), ...) are replaced with: kmalloc_flex(*PTR, FAM, COUNT, ...) (where TYPE may also be *VAR) The resulting allocations no longer return "void *", instead returning "TYPE *". Signed-off-by: Kees Cook

nfc: llcp: Fix memleak in nfc_llcp_send_ui_frame().

2026-01-27T03:51:46Z

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/skbuff.c:6671 sock_alloc_send_pskb+0x379/0x3e0 net/core/sock.c:2965 sock_alloc_send_skb include/net/sock.h:1859 [inline] nfc_alloc_send_skb+0x45/0x80 net/nfc/core.c:724 nfc_llcp_send_ui_frame+0x162/0x360 net/nfc/llcp_commands.c:766 llcp_sock_sendmsg+0x14c/0x1d0 net/nfc/llcp_sock.c:814 sock_sendmsg_nosec net/socket.c:727 [inline] __sock_sendmsg net/socket.c:742 [inline] __sys_sendto+0x2d8/0x2f0 net/socket.c:2244 __do_sys_sendto net/socket.c:2251 [inline] __se_sys_sendto net/socket.c:2247 [inline] __x64_sys_sendto+0x28/0x30 net/socket.c:2247 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 Fixes: 94f418a20664 ("NFC: UI frame sending routine implementation") Reported-by: syzbot+f2d245f1d76bbfa50e4c@syzkaller.appspotmail.com Closes: https://lore.kernel.org/netdev/697569c7.a00a0220.33ccc7.0014.GAE@google.com/T/#u Signed-off-by: Kuniyuki Iwashima Reviewed-by: Simon Horman Link: https://patch.msgid.link/20260125010214.1572439-1-kuniyu@google.com Signed-off-by: Jakub Kicinski

treewide, timers: Rename from_timer() to timer_container_of()

2025-06-08T07:07:37Z

Move this API to the canonical timer_*() namespace. [ tglx: Redone against pre rc1 ] Signed-off-by: Ingo Molnar Signed-off-by: Thomas Gleixner Link: https://lore.kernel.org/all/aB2X0jCKQO56WdMt@gmail.com

treewide: Switch/rename to timer_delete[_sync]()

2025-04-05T08:30:12Z

timer_delete[_sync]() replaces del_timer[_sync](). Convert the whole tree over and remove the historical wrapper inlines. Conversion was done with coccinelle plus manual fixups where necessary. Signed-off-by: Thomas Gleixner Signed-off-by: Ingo Molnar

nfc: llcp_core: Hold a ref to llcp_local->dev when holding a ref to llcp_local

2023-12-25T07:29:04Z

llcp_sock_sendmsg() calls nfc_llcp_send_ui_frame() which in turn calls nfc_alloc_send_skb(), which accesses the nfc_dev from the llcp_sock for getting the headroom and tailroom needed for skb allocation. Parallelly the nfc_dev can be freed, as the refcount is decreased via nfc_free_device(), leading to a UAF reported by Syzkaller, which can be summarized as follows: (1) llcp_sock_sendmsg() -> nfc_llcp_send_ui_frame() -> nfc_alloc_send_skb() -> Dereference *nfc_dev (2) virtual_ncidev_close() -> nci_free_device() -> nfc_free_device() -> put_device() -> nfc_release() -> Free *nfc_dev When a reference to llcp_local is acquired, we do not acquire the same for the nfc_dev. This leads to freeing even when the llcp_local is in use, and this is the case with the UAF described above too. Thus, when we acquire a reference to llcp_local, we should acquire a reference to nfc_dev, and release the references appropriately later. References for llcp_local is initialized in nfc_llcp_register_device() (which is called by nfc_register_device()). Thus, we should acquire a reference to nfc_dev there. nfc_unregister_device() calls nfc_llcp_unregister_device() which in turn calls nfc_llcp_local_put(). Thus, the reference to nfc_dev is appropriately released later. Reported-and-tested-by: syzbot+bbe84a4010eeea00982d@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=bbe84a4010eeea00982d Fixes: c7aa12252f51 ("NFC: Take a reference on the LLCP local pointer when creating a socket") Reviewed-by: Suman Ghosh Signed-off-by: Siddh Raman Pant Reviewed-by: Krzysztof Kozlowski Signed-off-by: David S. Miller

net: nfc: fix races in nfc_llcp_sock_get() and nfc_llcp_sock_get_sn()

2023-10-11T02:44:44Z

Sili Luo reported a race in nfc_llcp_sock_get(), leading to UAF. Getting a reference on the socket found in a lookup while holding a lock should happen before releasing the lock. nfc_llcp_sock_get_sn() has a similar problem. Finally nfc_llcp_recv_snl() needs to make sure the socket found by nfc_llcp_sock_from_sn() does not disappear. Fixes: 8f50020ed9b8 ("NFC: LLCP late binding") Reported-by: Sili Luo Signed-off-by: Eric Dumazet Cc: Willy Tarreau Reviewed-by: Krzysztof Kozlowski Link: https://lore.kernel.org/r/20231009123110.3735515-1-edumazet@google.com Signed-off-by: Jakub Kicinski

net: nfc: llcp: Add lock when modifying device list

2023-10-03T14:39:31Z

The device list needs its associated lock held when modifying it, or the list could become corrupted, as syzbot discovered. Reported-and-tested-by: syzbot+c1d0a03d305972dbbe14@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=c1d0a03d305972dbbe14 Signed-off-by: Jeremy Cline Reviewed-by: Simon Horman Fixes: 6709d4b7bc2e ("net: nfc: Fix use-after-free caused by nfc_llcp_find_local") Link: https://lore.kernel.org/r/20230908235853.1319596-1-jeremy@jcline.org Signed-off-by: Jakub Kicinski