Re: [syzbot] [net?] BUG: sleeping function called from invalid context in __lock_sock_fast

[Paolo Abeni]

On Fri, 2023-06-23 at 07:38 -0700, syzbot wrote:
> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    98e95872f2b8 Merge branch 'mptcp-expose-more-info-and-smal..
> git tree:       net-next
> console output: https://syzkaller.appspot.com/x/log.txt?x=109c5c1b280000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=a4a7d74e6a7c3211
> dashboard link: https://syzkaller.appspot.com/bug?extid=c54a9e997982d1a7dc11
> compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
> 
> Unfortunately, I don't have any reproducer for this issue yet.
> 
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/9846b6358605/disk-98e95872.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/c2ebfcba122e/vmlinux-98e95872.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/c5c7c23565e4/bzImage-98e95872.xz
> 
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+c54a9e997982d1a7dc11@xxxxxxxxxxxxxxxxxxxxxxxxx
> 
> BUG: sleeping function called from invalid context at net/core/sock.c:3549
> in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 10350, name: syz-executor.3
> preempt_count: 1, expected: 0
> RCU nest depth: 1, expected: 0
> 7 locks held by syz-executor.3/10350:
>  #0: ffffffff8e125408 (sock_diag_mutex){+.+.}-{3:3}, at: sock_diag_rcv+0x1b/0x40 net/core/sock_diag.c:279
>  #1: ffffffff8e125588 (sock_diag_table_mutex){+.+.}-{3:3}, at: sock_diag_rcv_msg net/core/sock_diag.c:259 [inline]
>  #1: ffffffff8e125588 (sock_diag_table_mutex){+.+.}-{3:3}, at: sock_diag_rcv_msg+0x2d2/0x440 net/core/sock_diag.c:248
>  #2: ffff88802f311688 (nlk_cb_mutex-SOCK_DIAG){+.+.}-{3:3}, at: netlink_dump+0xbe/0xc50 net/netlink/af_netlink.c:2215
>  #3: ffffffff8e29a628 (inet_diag_table_mutex){+.+.}-{3:3}, at: inet_diag_lock_handler+0x6e/0x100 net/ipv4/inet_diag.c:63
>  #4: ffffffff8c7990c0 (rcu_read_lock){....}-{1:2}, at: mptcp_diag_dump_listeners net/mptcp/mptcp_diag.c:95 [inline]
>  #4: ffffffff8c7990c0 (rcu_read_lock){....}-{1:2}, at: mptcp_diag_dump+0x7c8/0x1330 net/mptcp/mptcp_diag.c:197
>  #5: ffffc9000130c330 (&h->lhash2[i].lock){+.+.}-{2:2}, at: spin_lock include/linux/spinlock.h:350 [inline]
>  #5: ffffc9000130c330 (&h->lhash2[i].lock){+.+.}-{2:2}, at: mptcp_diag_dump_listeners net/mptcp/mptcp_diag.c:98 [inline]
>  #5: ffffc9000130c330 (&h->lhash2[i].lock){+.+.}-{2:2}, at: mptcp_diag_dump+0x838/0x1330 net/mptcp/mptcp_diag.c:197
>  #6: ffff88805c820cf0 (msk_lock-AF_INET){+.+.}-{0:0}, at: mptcp_diag_get_info+0x1ae/0x380 net/mptcp/mptcp_diag.c:224
> Preemption disabled at:
> [<0000000000000000>] 0x0
> CPU: 1 PID: 10350 Comm: syz-executor.3 Not tainted 6.4.0-rc6-syzkaller-01415-g98e95872f2b8 #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/27/2023
> Call Trace:
>  <TASK>
>  __dump_stack lib/dump_stack.c:88 [inline]
>  dump_stack_lvl+0x136/0x150 lib/dump_stack.c:106
>  __might_resched+0x358/0x580 kernel/sched/core.c:10153
>  __lock_sock_fast+0x25/0xe0 net/core/sock.c:3549
>  lock_sock_fast include/net/sock.h:1744 [inline]
>  mptcp_diag_fill_info+0x45c/0x9c0 net/mptcp/sockopt.c:930
>  mptcp_diag_get_info+0x1ae/0x380 net/mptcp/mptcp_diag.c:224
>  inet_sk_diag_fill+0x1258/0x1fd0 net/ipv4/inet_diag.c:342
>  sk_diag_dump net/mptcp/mptcp_diag.c:24 [inline]
>  sk_diag_dump net/mptcp/mptcp_diag.c:16 [inline]
>  mptcp_diag_dump_listeners net/mptcp/mptcp_diag.c:125 [inline]
>  mptcp_diag_dump+0xc5e/0x1330 net/mptcp/mptcp_diag.c:197
>  __inet_diag_dump+0x114/0x2e0 net/ipv4/inet_diag.c:1179
>  inet_diag_dump_compat+0x209/0x290 net/ipv4/inet_diag.c:1287
>  netlink_dump+0x570/0xc50 net/netlink/af_netlink.c:2268
>  __netlink_dump_start+0x6c0/0x9b0 net/netlink/af_netlink.c:2375
>  netlink_dump_start include/linux/netlink.h:330 [inline]
>  inet_diag_rcv_msg_compat+0x26d/0x2d0 net/ipv4/inet_diag.c:1321
>  __sock_diag_cmd net/core/sock_diag.c:240 [inline]
>  sock_diag_rcv_msg+0x2eb/0x440 net/core/sock_diag.c:269
>  netlink_rcv_skb+0x165/0x440 net/netlink/af_netlink.c:2548
>  sock_diag_rcv+0x2a/0x40 net/core/sock_diag.c:280
>  netlink_unicast_kernel net/netlink/af_netlink.c:1339 [inline]
>  netlink_unicast+0x547/0x7f0 net/netlink/af_netlink.c:1365
>  netlink_sendmsg+0x925/0xe30 net/netlink/af_netlink.c:1913
>  sock_sendmsg_nosec net/socket.c:724 [inline]
>  sock_sendmsg+0xde/0x190 net/socket.c:747
>  splice_to_socket+0x964/0xee0 fs/splice.c:915
>  do_splice_from fs/splice.c:967 [inline]
>  direct_splice_actor+0x114/0x180 fs/splice.c:1155
>  splice_direct_to_actor+0x34a/0x9c0 fs/splice.c:1101
>  do_splice_direct+0x1ad/0x280 fs/splice.c:1207
>  do_sendfile+0xb19/0x12c0 fs/read_write.c:1254
>  __do_sys_sendfile64 fs/read_write.c:1322 [inline]
>  __se_sys_sendfile64 fs/read_write.c:1308 [inline]
>  __x64_sys_sendfile64+0x1d0/0x210 fs/read_write.c:1308
>  do_syscall_x64 arch/x86/entry/common.c:50 [inline]
>  do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
>  entry_SYSCALL_64_after_hwframe+0x63/0xcd
> RIP: 0033:0x7fa74588c389
> Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 f1 19 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
> RSP: 002b:00007fa7443fe168 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
> RAX: ffffffffffffffda RBX: 00007fa7459ac050 RCX: 00007fa74588c389
> RDX: 0000000000000000 RSI: 0000000000000006 RDI: 0000000000000009
> RBP: 00007fa7458d7493 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000021fd1ee9 R11: 0000000000000246 R12: 0000000000000000
> R13: 00007ffca549394f R14: 00007fa7443fe300 R15: 0000000000022000
>  </TASK>
> 
> 
> ---

#syz fix: mptcp: ensure listener is unhashed before updating the sk status

Sorry for noise,

/P