syzbot


possible deadlock in sock_map_unref

Status: upstream: reported on 2024/04/08 14:20
Subsystems: bpf net
[Documentation on labels]
Reported-by: syzbot+850ca6a3ba35c8699832@syzkaller.appspotmail.com
First crash: 47d, last: 4d23h
Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [bpf?] [net?] possible deadlock in sock_map_unref 0 (1) 2024/04/08 14:20

Sample crash report:
======================================================
WARNING: possible circular locking dependency detected
6.9.0-rc6-syzkaller-00133-g19e35f24750d #0 Not tainted
------------------------------------------------------
syz-executor.4/19741 is trying to acquire lock:
ffff88807d42ebf0 (clock-AF_UNIX){++..}-{2:2}, at: sock_map_del_link net/core/sock_map.c:163 [inline]
ffff88807d42ebf0 (clock-AF_UNIX){++..}-{2:2}, at: sock_map_unref+0x442/0x5e0 net/core/sock_map.c:180

but task is already holding lock:
ffff888068f50200 (&stab->lock){+.-.}-{2:2}, at: spin_lock_bh include/linux/spinlock.h:356 [inline]
ffff888068f50200 (&stab->lock){+.-.}-{2:2}, at: sock_map_update_common+0x1b6/0x5b0 net/core/sock_map.c:493

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&stab->lock){+.-.}-{2:2}:
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5754
       __raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline]
       _raw_spin_lock_bh+0x35/0x50 kernel/locking/spinlock.c:178
       spin_lock_bh include/linux/spinlock.h:356 [inline]
       __sock_map_delete net/core/sock_map.c:417 [inline]
       sock_map_delete_elem+0x175/0x250 net/core/sock_map.c:449
       0xffffffffa0001cf3
       bpf_dispatcher_nop_func include/linux/bpf.h:1234 [inline]
       __bpf_prog_run include/linux/filter.h:657 [inline]
       bpf_prog_run include/linux/filter.h:664 [inline]
       __bpf_trace_run kernel/trace/bpf_trace.c:2381 [inline]
       bpf_trace_run2+0x204/0x420 kernel/trace/bpf_trace.c:2420
       trace_kfree include/trace/events/kmem.h:94 [inline]
       kfree+0x2af/0x3a0 mm/slub.c:4377
       __bpf_prog_put_noref+0xd7/0x310 kernel/bpf/syscall.c:2244
       bpf_prog_put_deferred+0x2f3/0x3e0 kernel/bpf/syscall.c:2270
       __bpf_prog_put kernel/bpf/syscall.c:2282 [inline]
       bpf_prog_put+0x264/0x2a0 kernel/bpf/syscall.c:2289
       psock_set_prog include/linux/skmsg.h:477 [inline]
       sk_psock_stop_verdict net/core/skmsg.c:1247 [inline]
       sk_psock_drop+0x214/0x500 net/core/skmsg.c:843
       sk_psock_put include/linux/skmsg.h:459 [inline]
       sock_map_close+0x209/0x2d0 net/core/sock_map.c:1654
       unix_release+0x85/0xc0 net/unix/af_unix.c:1048
       __sock_release net/socket.c:659 [inline]
       sock_close+0xbc/0x240 net/socket.c:1421
       __fput+0x429/0x8a0 fs/file_table.c:422
       __do_sys_close fs/open.c:1556 [inline]
       __se_sys_close fs/open.c:1541 [inline]
       __x64_sys_close+0x7f/0x110 fs/open.c:1541
       do_syscall_x64 arch/x86/entry/common.c:52 [inline]
       do_syscall_64+0xf5/0x240 arch/x86/entry/common.c:83
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #0 (clock-AF_UNIX){++..}-{2:2}:
       check_prev_add kernel/locking/lockdep.c:3134 [inline]
       check_prevs_add kernel/locking/lockdep.c:3253 [inline]
       validate_chain+0x18cb/0x58e0 kernel/locking/lockdep.c:3869
       __lock_acquire+0x1346/0x1fd0 kernel/locking/lockdep.c:5137
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5754
       __raw_write_lock_bh include/linux/rwlock_api_smp.h:202 [inline]
       _raw_write_lock_bh+0x35/0x50 kernel/locking/spinlock.c:334
       sock_map_del_link net/core/sock_map.c:163 [inline]
       sock_map_unref+0x442/0x5e0 net/core/sock_map.c:180
       sock_map_update_common+0x4f0/0x5b0 net/core/sock_map.c:506
       sock_map_update_elem_sys+0x55f/0x910 net/core/sock_map.c:582
       map_update_elem+0x53a/0x6f0 kernel/bpf/syscall.c:1641
       __sys_bpf+0x76f/0x810 kernel/bpf/syscall.c:5648
       __do_sys_bpf kernel/bpf/syscall.c:5767 [inline]
       __se_sys_bpf kernel/bpf/syscall.c:5765 [inline]
       __x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:5765
       do_syscall_x64 arch/x86/entry/common.c:52 [inline]
       do_syscall_64+0xf5/0x240 arch/x86/entry/common.c:83
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&stab->lock);
                               lock(clock-AF_UNIX);
                               lock(&stab->lock);
  lock(clock-AF_UNIX);

 *** DEADLOCK ***

3 locks held by syz-executor.4/19741:
 #0: ffff88807d42ea58 (sk_lock-AF_UNIX){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1673 [inline]
 #0: ffff88807d42ea58 (sk_lock-AF_UNIX){+.+.}-{0:0}, at: sock_map_sk_acquire net/core/sock_map.c:117 [inline]
 #0: ffff88807d42ea58 (sk_lock-AF_UNIX){+.+.}-{0:0}, at: sock_map_update_elem_sys+0x1cc/0x910 net/core/sock_map.c:578
 #1: ffffffff8e334da0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:329 [inline]
 #1: ffffffff8e334da0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:781 [inline]
 #1: ffffffff8e334da0 (rcu_read_lock){....}-{1:2}, at: sock_map_sk_acquire net/core/sock_map.c:118 [inline]
 #1: ffffffff8e334da0 (rcu_read_lock){....}-{1:2}, at: sock_map_update_elem_sys+0x1d8/0x910 net/core/sock_map.c:578
 #2: ffff888068f50200 (&stab->lock){+.-.}-{2:2}, at: spin_lock_bh include/linux/spinlock.h:356 [inline]
 #2: ffff888068f50200 (&stab->lock){+.-.}-{2:2}, at: sock_map_update_common+0x1b6/0x5b0 net/core/sock_map.c:493

stack backtrace:
CPU: 0 PID: 19741 Comm: syz-executor.4 Not tainted 6.9.0-rc6-syzkaller-00133-g19e35f24750d #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:114
 check_noncircular+0x36a/0x4a0 kernel/locking/lockdep.c:2187
 check_prev_add kernel/locking/lockdep.c:3134 [inline]
 check_prevs_add kernel/locking/lockdep.c:3253 [inline]
 validate_chain+0x18cb/0x58e0 kernel/locking/lockdep.c:3869
 __lock_acquire+0x1346/0x1fd0 kernel/locking/lockdep.c:5137
 lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5754
 __raw_write_lock_bh include/linux/rwlock_api_smp.h:202 [inline]
 _raw_write_lock_bh+0x35/0x50 kernel/locking/spinlock.c:334
 sock_map_del_link net/core/sock_map.c:163 [inline]
 sock_map_unref+0x442/0x5e0 net/core/sock_map.c:180
 sock_map_update_common+0x4f0/0x5b0 net/core/sock_map.c:506
 sock_map_update_elem_sys+0x55f/0x910 net/core/sock_map.c:582
 map_update_elem+0x53a/0x6f0 kernel/bpf/syscall.c:1641
 __sys_bpf+0x76f/0x810 kernel/bpf/syscall.c:5648
 __do_sys_bpf kernel/bpf/syscall.c:5767 [inline]
 __se_sys_bpf kernel/bpf/syscall.c:5765 [inline]
 __x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:5765
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf5/0x240 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fac2507dd69
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 20 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 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fac25db60c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000141
RAX: ffffffffffffffda RBX: 00007fac251abf80 RCX: 00007fac2507dd69
RDX: 0000000000000020 RSI: 00000000200000c0 RDI: 0000000000000002
RBP: 00007fac250ca49e R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000000b R14: 00007fac251abf80 R15: 00007fff60c72ac8
 </TASK>

Crashes (9):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2024/05/08 09:50 net 19e35f24750d 4cf3f9b3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce possible deadlock in sock_map_unref
2024/05/01 01:54 bpf 3e9bc0472b91 9e0e6af1 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-bpf-kasan-gce possible deadlock in sock_map_unref
2024/04/04 14:17 net f99c5f563c17 0ee3535e .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce possible deadlock in sock_map_unref
2024/05/17 04:19 net-next 1b294a1f3561 c2e07261 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce possible deadlock in sock_map_unref
2024/05/05 05:37 net-next 173e7622ccb3 610f2a54 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce possible deadlock in sock_map_unref
2024/05/04 11:42 net-next 173e7622ccb3 610f2a54 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce possible deadlock in sock_map_unref
2024/05/03 17:50 net-next a17ef9e6c2c1 375d4445 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce possible deadlock in sock_map_unref
2024/04/26 09:21 net-next 2bd87951de65 8bdc0f22 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce possible deadlock in sock_map_unref
2024/04/10 04:13 linux-next a053fd3ca5d1 56086b24 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root possible deadlock in sock_map_unref
* Struck through repros no longer work on HEAD.