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

From: syzbot
Date: Mon Mar 18 2024 - 12:03:36 EST

Next message: Stanislav Fomichev: "Re: [PATCH V2 bpf-next 1/2] bpf: add bpf_task_get_cgroup kfunc"
Previous message: syzbot: "[syzbot] [bpf?] [net?] possible deadlock in try_to_wake_up (4)"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]

Hello,

syzbot found the following issue on:

HEAD commit: aae08491b943 MAINTAINERS: Update email address for Quentin..
git tree: bpf
console output: https://syzkaller.appspot.com/x/log.txt?x=1638d769180000
kernel config: https://syzkaller.appspot.com/x/.config?x=6fb1be60a193d440
dashboard link: https://syzkaller.appspot.com/bug?extid=4ac2fe2b496abca8fa4b
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/95cdb255229a/disk-aae08491.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/dc336e48f648/vmlinux-aae08491.xz
kernel image: https://storage.googleapis.com/syzbot-assets/1abbb4a4ac37/bzImage-aae08491.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+4ac2fe2b496abca8fa4b@xxxxxxxxxxxxxxxxxxxxxxxxx

======================================================
WARNING: possible circular locking dependency detected
6.8.0-syzkaller-05221-gaae08491b943 #0 Not tainted
------------------------------------------------------
syz-executor.4/12756 is trying to acquire lock:
ffff888054905a00 (&stab->lock){+.-.}-{2:2}, at: spin_lock_bh include/linux/spinlock.h:356 [inline]
ffff888054905a00 (&stab->lock){+.-.}-{2:2}, at: __sock_map_delete net/core/sock_map.c:414 [inline]
ffff888054905a00 (&stab->lock){+.-.}-{2:2}, at: sock_map_delete_elem+0x97/0x140 net/core/sock_map.c:446

but task is already holding lock:
ffff888045774290 (&psock->link_lock){+...}-{2:2}, at: spin_lock_bh include/linux/spinlock.h:356 [inline]
ffff888045774290 (&psock->link_lock){+...}-{2:2}, at: sock_map_del_link net/core/sock_map.c:145 [inline]
ffff888045774290 (&psock->link_lock){+...}-{2:2}, at: sock_map_unref+0xcc/0x5e0 net/core/sock_map.c:180

which lock already depends on the new lock.

the existing dependency chain (in reverse order) is:

-> #1 (&psock->link_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_add_link net/core/sock_map.c:134 [inline]
sock_map_update_common+0x31c/0x5b0 net/core/sock_map.c:500
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

-> #0 (&stab->lock){+.-.}-{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_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
bpf_prog_174084c74af853ee+0x42/0x67
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
sk_psock_free_link include/linux/skmsg.h:421 [inline]
sock_map_del_link net/core/sock_map.c:158 [inline]
sock_map_unref+0x3ac/0x5e0 net/core/sock_map.c:180
sock_hash_delete_elem+0x27e/0x300 net/core/sock_map.c:943
map_delete_elem+0x464/0x5e0 kernel/bpf/syscall.c:1696
__sys_bpf+0x598/0x810 kernel/bpf/syscall.c:5622
__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(&psock->link_lock);
lock(&stab->lock);
lock(&psock->link_lock);
lock(&stab->lock);

*** DEADLOCK ***

4 locks held by syz-executor.4/12756:
#0: ffffffff8e131920 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:298 [inline]
#0: ffffffff8e131920 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:750 [inline]
#0: ffffffff8e131920 (rcu_read_lock){....}-{1:2}, at: map_delete_elem+0x388/0x5e0 kernel/bpf/syscall.c:1695
#1: ffff88802b169b68 (&htab->buckets[i].lock){+...}-{2:2}, at: spin_lock_bh include/linux/spinlock.h:356 [inline]
#1: ffff88802b169b68 (&htab->buckets[i].lock){+...}-{2:2}, at: sock_hash_delete_elem+0xb0/0x300 net/core/sock_map.c:939
#2: ffff888045774290 (&psock->link_lock){+...}-{2:2}, at: spin_lock_bh include/linux/spinlock.h:356 [inline]
#2: ffff888045774290 (&psock->link_lock){+...}-{2:2}, at: sock_map_del_link net/core/sock_map.c:145 [inline]
#2: ffff888045774290 (&psock->link_lock){+...}-{2:2}, at: sock_map_unref+0xcc/0x5e0 net/core/sock_map.c:180
#3: ffffffff8e131920 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:298 [inline]
#3: ffffffff8e131920 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:750 [inline]
#3: ffffffff8e131920 (rcu_read_lock){....}-{1:2}, at: __bpf_trace_run kernel/trace/bpf_trace.c:2380 [inline]
#3: ffffffff8e131920 (rcu_read_lock){....}-{1:2}, at: bpf_trace_run2+0x114/0x420 kernel/trace/bpf_trace.c:2420

stack backtrace:
CPU: 1 PID: 12756 Comm: syz-executor.4 Not tainted 6.8.0-syzkaller-05221-gaae08491b943 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/29/2024
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_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
bpf_prog_174084c74af853ee+0x42/0x67
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
sk_psock_free_link include/linux/skmsg.h:421 [inline]
sock_map_del_link net/core/sock_map.c:158 [inline]
sock_map_unref+0x3ac/0x5e0 net/core/sock_map.c:180
sock_hash_delete_elem+0x27e/0x300 net/core/sock_map.c:943
map_delete_elem+0x464/0x5e0 kernel/bpf/syscall.c:1696
__sys_bpf+0x598/0x810 kernel/bpf/syscall.c:5622
__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: 0033:0x7f94ec87dda9
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:00007f94ed5410c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000141
RAX: ffffffffffffffda RBX: 00007f94ec9abf80 RCX: 00007f94ec87dda9
RDX: 0000000000000020 RSI: 0000000020000080 RDI: 0000000000000003
RBP: 00007f94ec8ca47a R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000000b R14: 00007f94ec9abf80 R15: 00007ffd0775a478
</TASK>

---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxx.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)

If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup

Next message: Stanislav Fomichev: "Re: [PATCH V2 bpf-next 1/2] bpf: add bpf_task_get_cgroup kfunc"
Previous message: syzbot: "[syzbot] [bpf?] [net?] possible deadlock in try_to_wake_up (4)"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]