kernel/linux.git/net/unix, branch v5.15.209

af_unix: read UNIX_DIAG_VFS data under unix_state_lock

2026-06-01T15:35:03+00:00

[ Upstream commit 39897df386376912d561d4946499379effa1e7ef ] Exact UNIX diag lookups hold a reference to the socket, but not to u->path. Meanwhile, unix_release_sock() clears u->path under unix_state_lock() and drops the path reference after unlocking. Read the inode and device numbers for UNIX_DIAG_VFS while holding unix_state_lock(), then emit the netlink attribute after dropping the lock. This keeps the VFS data stable while the reply is being built. Fixes: 5f7b0569460b ("unix_diag: Unix inode info NLA") Reported-by: Yifan Wu Reported-by: Juefei Pu Co-developed-by: Yuan Tan Signed-off-by: Yuan Tan Suggested-by: Xin Liu Tested-by: Ren Wei Signed-off-by: Jiexun Wang Signed-off-by: Ren Wei Reviewed-by: Kuniyuki Iwashima Link: https://patch.msgid.link/20260407080015.1744197-1-n05ec@lzu.edu.cn Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

af_unix: Don't leave consecutive consumed OOB skbs.

2025-10-02T11:39:14+00:00

commit 32ca245464e1479bfea8592b9db227fdc1641705 upstream. Jann Horn reported a use-after-free in unix_stream_read_generic(). The following sequences reproduce the issue: $ python3 from socket import * s1, s2 = socketpair(AF_UNIX, SOCK_STREAM) s1.send(b'x', MSG_OOB) s2.recv(1, MSG_OOB) # leave a consumed OOB skb s1.send(b'y', MSG_OOB) s2.recv(1, MSG_OOB) # leave a consumed OOB skb s1.send(b'z', MSG_OOB) s2.recv(1) # recv 'z' illegally s2.recv(1, MSG_OOB) # access 'z' skb (use-after-free) Even though a user reads OOB data, the skb holding the data stays on the recv queue to mark the OOB boundary and break the next recv(). After the last send() in the scenario above, the sk2's recv queue has 2 leading consumed OOB skbs and 1 real OOB skb. Then, the following happens during the next recv() without MSG_OOB 1. unix_stream_read_generic() peeks the first consumed OOB skb 2. manage_oob() returns the next consumed OOB skb 3. unix_stream_read_generic() fetches the next not-yet-consumed OOB skb 4. unix_stream_read_generic() reads and frees the OOB skb , and the last recv(MSG_OOB) triggers KASAN splat. The 3. above occurs because of the SO_PEEK_OFF code, which does not expect unix_skb_len(skb) to be 0, but this is true for such consumed OOB skbs. while (skip >= unix_skb_len(skb)) { skip -= unix_skb_len(skb); skb = skb_peek_next(skb, &sk->sk_receive_queue); ... } In addition to this use-after-free, there is another issue that ioctl(SIOCATMARK) does not function properly with consecutive consumed OOB skbs. So, nothing good comes out of such a situation. Instead of complicating manage_oob(), ioctl() handling, and the next ECONNRESET fix by introducing a loop for consecutive consumed OOB skbs, let's not leave such consecutive OOB unnecessarily. Now, while receiving an OOB skb in unix_stream_recv_urg(), if its previous skb is a consumed OOB skb, it is freed. [0]: BUG: KASAN: slab-use-after-free in unix_stream_read_actor (net/unix/af_unix.c:3027) Read of size 4 at addr ffff888106ef2904 by task python3/315 CPU: 2 UID: 0 PID: 315 Comm: python3 Not tainted 6.16.0-rc1-00407-gec315832f6f9 #8 PREEMPT(voluntary) Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-4.fc42 04/01/2014 Call Trace: dump_stack_lvl (lib/dump_stack.c:122) print_report (mm/kasan/report.c:409 mm/kasan/report.c:521) kasan_report (mm/kasan/report.c:636) unix_stream_read_actor (net/unix/af_unix.c:3027) unix_stream_read_generic (net/unix/af_unix.c:2708 net/unix/af_unix.c:2847) unix_stream_recvmsg (net/unix/af_unix.c:3048) sock_recvmsg (net/socket.c:1063 (discriminator 20) net/socket.c:1085 (discriminator 20)) __sys_recvfrom (net/socket.c:2278) __x64_sys_recvfrom (net/socket.c:2291 (discriminator 1) net/socket.c:2287 (discriminator 1) net/socket.c:2287 (discriminator 1)) do_syscall_64 (arch/x86/entry/syscall_64.c:63 (discriminator 1) arch/x86/entry/syscall_64.c:94 (discriminator 1)) entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130) RIP: 0033:0x7f8911fcea06 Code: 5d e8 41 8b 93 08 03 00 00 59 5e 48 83 f8 fc 75 19 83 e2 39 83 fa 08 75 11 e8 26 ff ff ff 66 0f 1f 44 00 00 48 8b 45 10 0f 05 <48> 8b 5d f8 c9 c3 0f 1f 40 00 f3 0f 1e fa 55 48 89 e5 48 83 ec 08 RSP: 002b:00007fffdb0dccb0 EFLAGS: 00000202 ORIG_RAX: 000000000000002d RAX: ffffffffffffffda RBX: 00007fffdb0dcdc8 RCX: 00007f8911fcea06 RDX: 0000000000000001 RSI: 00007f8911a5e060 RDI: 0000000000000006 RBP: 00007fffdb0dccd0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000001 R11: 0000000000000202 R12: 00007f89119a7d20 R13: ffffffffc4653600 R14: 0000000000000000 R15: 0000000000000000 Allocated by task 315: kasan_save_stack (mm/kasan/common.c:48) kasan_save_track (mm/kasan/common.c:60 (discriminator 1) mm/kasan/common.c:69 (discriminator 1)) __kasan_slab_alloc (mm/kasan/common.c:348) kmem_cache_alloc_node_noprof (./include/linux/kasan.h:250 mm/slub.c:4148 mm/slub.c:4197 mm/slub.c:4249) __alloc_skb (net/core/skbuff.c:660 (discriminator 4)) alloc_skb_with_frags (./include/linux/skbuff.h:1336 net/core/skbuff.c:6668) sock_alloc_send_pskb (net/core/sock.c:2993) unix_stream_sendmsg (./include/net/sock.h:1847 net/unix/af_unix.c:2256 net/unix/af_unix.c:2418) __sys_sendto (net/socket.c:712 (discriminator 20) net/socket.c:727 (discriminator 20) net/socket.c:2226 (discriminator 20)) __x64_sys_sendto (net/socket.c:2233 (discriminator 1) net/socket.c:2229 (discriminator 1) net/socket.c:2229 (discriminator 1)) do_syscall_64 (arch/x86/entry/syscall_64.c:63 (discriminator 1) arch/x86/entry/syscall_64.c:94 (discriminator 1)) entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130) Freed by task 315: kasan_save_stack (mm/kasan/common.c:48) kasan_save_track (mm/kasan/common.c:60 (discriminator 1) mm/kasan/common.c:69 (discriminator 1)) kasan_save_free_info (mm/kasan/generic.c:579 (discriminator 1)) __kasan_slab_free (mm/kasan/common.c:271) kmem_cache_free (mm/slub.c:4643 (discriminator 3) mm/slub.c:4745 (discriminator 3)) unix_stream_read_generic (net/unix/af_unix.c:3010) unix_stream_recvmsg (net/unix/af_unix.c:3048) sock_recvmsg (net/socket.c:1063 (discriminator 20) net/socket.c:1085 (discriminator 20)) __sys_recvfrom (net/socket.c:2278) __x64_sys_recvfrom (net/socket.c:2291 (discriminator 1) net/socket.c:2287 (discriminator 1) net/socket.c:2287 (discriminator 1)) do_syscall_64 (arch/x86/entry/syscall_64.c:63 (discriminator 1) arch/x86/entry/syscall_64.c:94 (discriminator 1)) entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130) The buggy address belongs to the object at ffff888106ef28c0 which belongs to the cache skbuff_head_cache of size 224 The buggy address is located 68 bytes inside of freed 224-byte region [ffff888106ef28c0, ffff888106ef29a0) The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff888106ef3cc0 pfn:0x106ef2 head: order:1 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0 flags: 0x200000000000040(head|node=0|zone=2) page_type: f5(slab) raw: 0200000000000040 ffff8881001d28c0 ffffea000422fe00 0000000000000004 raw: ffff888106ef3cc0 0000000080190010 00000000f5000000 0000000000000000 head: 0200000000000040 ffff8881001d28c0 ffffea000422fe00 0000000000000004 head: ffff888106ef3cc0 0000000080190010 00000000f5000000 0000000000000000 head: 0200000000000001 ffffea00041bbc81 00000000ffffffff 00000000ffffffff head: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff888106ef2800: 00 00 00 00 00 00 00 00 00 00 00 00 fc fc fc fc ffff888106ef2880: fc fc fc fc fc fc fc fc fa fb fb fb fb fb fb fb >ffff888106ef2900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888106ef2980: fb fb fb fb fc fc fc fc fc fc fc fc fc fc fc fc ffff888106ef2a00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb Fixes: 314001f0bf92 ("af_unix: Add OOB support") Reported-by: Jann Horn Signed-off-by: Kuniyuki Iwashima Reviewed-by: Jann Horn Link: https://patch.msgid.link/20250619041457.1132791-2-kuni1840@gmail.com Signed-off-by: Paolo Abeni [Lee: Shifted hunk inside the if() statement and surrounded the else with {}'s) Signed-off-by: Lee Jones Signed-off-by: Greg Kroah-Hartman

af_unix: Don't set -ECONNRESET for consumed OOB skb.

2025-07-10T13:57:38+00:00

[ Upstream commit 2a5a4841846b079b5fca5752fe94e59346fbda40 ] Christian Brauner reported that even after MSG_OOB data is consumed, calling close() on the receiver socket causes the peer's recv() to return -ECONNRESET: 1. send() and recv() an OOB data. >>> from socket import * >>> s1, s2 = socketpair(AF_UNIX, SOCK_STREAM) >>> s1.send(b'x', MSG_OOB) 1 >>> s2.recv(1, MSG_OOB) b'x' 2. close() for s2 sets ECONNRESET to s1->sk_err even though s2 consumed the OOB data >>> s2.close() >>> s1.recv(10, MSG_DONTWAIT) ... ConnectionResetError: [Errno 104] Connection reset by peer Even after being consumed, the skb holding the OOB 1-byte data stays in the recv queue to mark the OOB boundary and break recv() at that point. This must be considered while close()ing a socket. Let's skip the leading consumed OOB skb while checking the -ECONNRESET condition in unix_release_sock(). Fixes: 314001f0bf92 ("af_unix: Add OOB support") Reported-by: Christian Brauner Closes: https://lore.kernel.org/netdev/20250529-sinkt-abfeuern-e7b08200c6b0@brauner/ Signed-off-by: Kuniyuki Iwashima Acked-by: Christian Brauner Link: https://patch.msgid.link/20250619041457.1132791-4-kuni1840@gmail.com Signed-off-by: Paolo Abeni Signed-off-by: Sasha Levin

af_unix: Remove put_pid()/put_cred() in copy_peercred().

2024-09-12T09:07:45+00:00

[ Upstream commit e4bd881d987121dbf1a288641491955a53d9f8f7 ] When (AF_UNIX, SOCK_STREAM) socket connect()s to a listening socket, the listener's sk_peer_pid/sk_peer_cred are copied to the client in copy_peercred(). Then, the client's sk_peer_pid and sk_peer_cred are always NULL, so we need not call put_pid() and put_cred() there. Signed-off-by: Kuniyuki Iwashima Signed-off-by: Paolo Abeni Signed-off-by: Sasha Levin

af_unix: Read with MSG_PEEK loops if the first unread byte is OOB

2024-07-05T07:14:19+00:00

[ Upstream commit a6736a0addd60fccc3a3508461d72314cc609772 ] Read with MSG_PEEK flag loops if the first byte to read is an OOB byte. commit 22dd70eb2c3d ("af_unix: Don't peek OOB data without MSG_OOB.") addresses the loop issue but does not address the issue that no data beyond OOB byte can be read. >>> from socket import * >>> c1, c2 = socketpair(AF_UNIX, SOCK_STREAM) >>> c1.send(b'a', MSG_OOB) 1 >>> c1.send(b'b') 1 >>> c2.recv(1, MSG_PEEK | MSG_DONTWAIT) b'b' >>> from socket import * >>> c1, c2 = socketpair(AF_UNIX, SOCK_STREAM) >>> c2.setsockopt(SOL_SOCKET, SO_OOBINLINE, 1) >>> c1.send(b'a', MSG_OOB) 1 >>> c1.send(b'b') 1 >>> c2.recv(1, MSG_PEEK | MSG_DONTWAIT) b'a' >>> c2.recv(1, MSG_PEEK | MSG_DONTWAIT) b'a' >>> c2.recv(1, MSG_DONTWAIT) b'a' >>> c2.recv(1, MSG_PEEK | MSG_DONTWAIT) b'b' >>> Fixes: 314001f0bf92 ("af_unix: Add OOB support") Signed-off-by: Rao Shoaib Reviewed-by: Kuniyuki Iwashima Link: https://lore.kernel.org/r/20240611084639.2248934-1-Rao.Shoaib@oracle.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

af_unix: Annotate data-race of sk->sk_shutdown in sk_diag_fill().

2024-07-05T07:14:09+00:00

[ Upstream commit efaf24e30ec39ebbea9112227485805a48b0ceb1 ] While dumping sockets via UNIX_DIAG, we do not hold unix_state_lock(). Let's use READ_ONCE() to read sk->sk_shutdown. Fixes: e4e541a84863 ("sock-diag: Report shutdown for inet and unix sockets (v2)") Signed-off-by: Kuniyuki Iwashima Signed-off-by: Paolo Abeni Signed-off-by: Sasha Levin

af_unix: Use skb_queue_len_lockless() in sk_diag_show_rqlen().

2024-07-05T07:14:09+00:00

[ Upstream commit 5d915e584d8408211d4567c22685aae8820bfc55 ] We can dump the socket queue length via UNIX_DIAG by specifying UDIAG_SHOW_RQLEN. If sk->sk_state is TCP_LISTEN, we return the recv queue length, but here we do not hold recvq lock. Let's use skb_queue_len_lockless() in sk_diag_show_rqlen(). Fixes: c9da99e6475f ("unix_diag: Fixup RQLEN extension report") Signed-off-by: Kuniyuki Iwashima Signed-off-by: Paolo Abeni Signed-off-by: Sasha Levin

af_unix: Use skb_queue_empty_lockless() in unix_release_sock().

2024-07-05T07:14:09+00:00

[ Upstream commit 83690b82d228b3570565ebd0b41873933238b97f ] If the socket type is SOCK_STREAM or SOCK_SEQPACKET, unix_release_sock() checks the length of the peer socket's recvq under unix_state_lock(). However, unix_stream_read_generic() calls skb_unlink() after releasing the lock. Also, for SOCK_SEQPACKET, __skb_try_recv_datagram() unlinks skb without unix_state_lock(). Thues, unix_state_lock() does not protect qlen. Let's use skb_queue_empty_lockless() in unix_release_sock(). Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Kuniyuki Iwashima Signed-off-by: Paolo Abeni Signed-off-by: Sasha Levin

af_unix: annotate lockless accesses to sk->sk_err

2024-07-05T07:14:08+00:00

[ Upstream commit cc04410af7de348234ac36a5f50c4ce416efdb4b ] unix_poll() and unix_dgram_poll() read sk->sk_err without any lock held. Add relevant READ_ONCE()/WRITE_ONCE() annotations. Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller Stable-dep-of: 83690b82d228 ("af_unix: Use skb_queue_empty_lockless() in unix_release_sock().") Signed-off-by: Sasha Levin

af_unix: Use unix_recvq_full_lockless() in unix_stream_connect().

2024-07-05T07:14:08+00:00

[ Upstream commit 45d872f0e65593176d880ec148f41ad7c02e40a7 ] Once sk->sk_state is changed to TCP_LISTEN, it never changes. unix_accept() takes advantage of this characteristics; it does not hold the listener's unix_state_lock() and only acquires recvq lock to pop one skb. It means unix_state_lock() does not prevent the queue length from changing in unix_stream_connect(). Thus, we need to use unix_recvq_full_lockless() to avoid data-race. Now we remove unix_recvq_full() as no one uses it. Note that we can remove READ_ONCE() for sk->sk_max_ack_backlog in unix_recvq_full_lockless() because of the following reasons: (1) For SOCK_DGRAM, it is a written-once field in unix_create1() (2) For SOCK_STREAM and SOCK_SEQPACKET, it is changed under the listener's unix_state_lock() in unix_listen(), and we hold the lock in unix_stream_connect() Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Kuniyuki Iwashima Signed-off-by: Paolo Abeni Signed-off-by: Sasha Levin