[syzbot] [bpf?] [net?] possible deadlock in sock_map_unref

From: syzbot
Date: Mon Apr 08 2024 - 10:21:48 EST

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Hello,

syzbot found the following issue on:

HEAD commit: f99c5f563c17 Merge tag 'nf-24-03-21' of git://git.kernel.o..
git tree: net
console output: https://syzkaller.appspot.com/x/log.txt?x=1363aaa9180000
kernel config: https://syzkaller.appspot.com/x/.config?x=6fb1be60a193d440
dashboard link: https://syzkaller.appspot.com/bug?extid=850ca6a3ba35c8699832
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/65d3f3eb786e/disk-f99c5f56.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/799cf7f28ff8/vmlinux-f99c5f56.xz
kernel image: https://storage.googleapis.com/syzbot-assets/ab26c60c3845/bzImage-f99c5f56.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+850ca6a3ba35c8699832@xxxxxxxxxxxxxxxxxxxxxxxxx

======================================================
WARNING: possible circular locking dependency detected
6.8.0-syzkaller-05271-gf99c5f563c17 #0 Not tainted
------------------------------------------------------
syz-executor.4/21902 is trying to acquire lock:
ffff88804ec83bf0 (clock-AF_UNIX){++..}-{2:2}, at: sock_map_del_link net/core/sock_map.c:163 [inline]
ffff88804ec83bf0 (clock-AF_UNIX){++..}-{2:2}, at: sock_map_unref+0x442/0x5e0 net/core/sock_map.c:180

but task is already holding lock:
ffff888066451200 (&stab->lock){+.-.}-{2:2}, at: spin_lock_bh include/linux/spinlock.h:356 [inline]
ffff888066451200 (&stab->lock){+.-.}-{2:2}, at: sock_map_update_common+0x1b6/0x5b0 net/core/sock_map.c:490

which lock already depends on the new lock.

the existing dependency chain (in reverse order) is:

-> #1 (&stab->lock){+.-.}-{2:2}:
lock_acquire+0x1e4/0x530 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:414 [inline]
sock_map_delete_elem+0x97/0x140 net/core/sock_map.c:446
0xffffffffa00048e6
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+0x291/0x380 mm/slub.c:4396
__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:475 [inline]
sk_psock_stop_strp net/core/skmsg.c:1156 [inline]
sk_psock_drop+0xe0/0x500 net/core/skmsg.c:841
sk_psock_put include/linux/skmsg.h:459 [inline]
sock_map_close+0x209/0x2d0 net/core/sock_map.c:1648
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:423
__do_sys_close fs/open.c:1557 [inline]
__se_sys_close fs/open.c:1542 [inline]
__x64_sys_close+0x7f/0x110 fs/open.c:1542
do_syscall_64+0xfb/0x240
entry_SYSCALL_64_after_hwframe+0x6d/0x75

-> #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+0x1e4/0x530 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:503
sock_map_update_elem_sys+0x55f/0x910 net/core/sock_map.c:579
map_update_elem+0x53a/0x6f0 kernel/bpf/syscall.c:1641
__sys_bpf+0x76f/0x810 kernel/bpf/syscall.c:5619
__do_sys_bpf kernel/bpf/syscall.c:5738 [inline]
__se_sys_bpf kernel/bpf/syscall.c:5736 [inline]
__x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:5736
do_syscall_64+0xfb/0x240
entry_SYSCALL_64_after_hwframe+0x6d/0x75

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.4/21902:
#0: ffff88804ec85a58 (sk_lock-AF_UNIX){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1671 [inline]
#0: ffff88804ec85a58 (sk_lock-AF_UNIX){+.+.}-{0:0}, at: sock_map_sk_acquire net/core/sock_map.c:117 [inline]
#0: ffff88804ec85a58 (sk_lock-AF_UNIX){+.+.}-{0:0}, at: sock_map_update_elem_sys+0x1cc/0x910 net/core/sock_map.c:575
#1: ffffffff8e131920 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:329 [inline]
#1: ffffffff8e131920 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:781 [inline]
#1: ffffffff8e131920 (rcu_read_lock){....}-{1:2}, at: sock_map_sk_acquire net/core/sock_map.c:118 [inline]
#1: ffffffff8e131920 (rcu_read_lock){....}-{1:2}, at: sock_map_update_elem_sys+0x1d8/0x910 net/core/sock_map.c:575
#2: ffff888066451200 (&stab->lock){+.-.}-{2:2}, at: spin_lock_bh include/linux/spinlock.h:356 [inline]
#2: ffff888066451200 (&stab->lock){+.-.}-{2:2}, at: sock_map_update_common+0x1b6/0x5b0 net/core/sock_map.c:490

stack backtrace:
CPU: 1 PID: 21902 Comm: syz-executor.4 Not tainted 6.8.0-syzkaller-05271-gf99c5f563c17 #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+0x1e7/0x2e0 lib/dump_stack.c:106
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+0x1e4/0x530 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:503
sock_map_update_elem_sys+0x55f/0x910 net/core/sock_map.c:579
map_update_elem+0x53a/0x6f0 kernel/bpf/syscall.c:1641
__sys_bpf+0x76f/0x810 kernel/bpf/syscall.c:5619
__do_sys_bpf kernel/bpf/syscall.c:5738 [inline]
__se_sys_bpf kernel/bpf/syscall.c:5736 [inline]
__x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:5736
do_syscall_64+0xfb/0x240
entry_SYSCALL_64_after_hwframe+0x6d/0x75
RIP: 0033:0x7f9934c7de69
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:00007f9935a7c0c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000141
RAX: ffffffffffffffda RBX: 00007f9934dac120 RCX: 00007f9934c7de69
RDX: 0000000000000020 RSI: 0000000020000880 RDI: 0000000000000002
RBP: 00007f9934cca47a R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000006e R14: 00007f9934dac120 R15: 00007fffdd7d6668
</TASK>

---
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Next message: Alexander Gordeev: "Re: [PATCH v4 4/5] s390/vfio-ap: Add write support to sysfs attr ap_config"
Previous message: Jason Gunthorpe: "Re: [PATCH v4 2/9] iommu: Replace sva_iommu with iommu_attach_handle"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]