[syzbot] [bpf?] possible deadlock in __bpf_ringbuf_reserve

From: syzbot
Date: Tue Mar 12 2024 - 12:41:46 EST

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Hello,

syzbot found the following issue on:

HEAD commit: df4793505abd Merge tag 'net-6.8-rc8' of git://git.kernel.o..
git tree: bpf
console+strace: https://syzkaller.appspot.com/x/log.txt?x=11fd0092180000
kernel config: https://syzkaller.appspot.com/x/.config?x=c11c5c676adb61f0
dashboard link: https://syzkaller.appspot.com/bug?extid=850aaf14624dc0c6d366
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1509c4ae180000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=10babc01180000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/d2e80ee1112b/disk-df479350.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/b35ea54cd190/vmlinux-df479350.xz
kernel image: https://storage.googleapis.com/syzbot-assets/59f69d999ad2/bzImage-df479350.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+850aaf14624dc0c6d366@xxxxxxxxxxxxxxxxxxxxxxxxx

============================================
WARNING: possible recursive locking detected
6.8.0-rc7-syzkaller-gdf4793505abd #0 Not tainted
--------------------------------------------
strace-static-x/5063 is trying to acquire lock:
ffffc900096f10d8 (&rb->spinlock){-.-.}-{2:2}, at: __bpf_ringbuf_reserve+0x211/0x4f0 kernel/bpf/ringbuf.c:424

but task is already holding lock:
ffffc900098410d8 (&rb->spinlock){-.-.}-{2:2}, at: __bpf_ringbuf_reserve+0x211/0x4f0 kernel/bpf/ringbuf.c:424

other info that might help us debug this:
Possible unsafe locking scenario:

CPU0
----
lock(&rb->spinlock);
lock(&rb->spinlock);

*** DEADLOCK ***

May be due to missing lock nesting notation

4 locks held by strace-static-x/5063:
#0: ffff88807857e068 (&pipe->mutex/1){+.+.}-{3:3}, at: __pipe_lock fs/pipe.c:103 [inline]
#0: ffff88807857e068 (&pipe->mutex/1){+.+.}-{3:3}, at: pipe_write+0x1cc/0x1a40 fs/pipe.c:465
#1: ffffffff8e130be0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:298 [inline]
#1: ffffffff8e130be0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:750 [inline]
#1: ffffffff8e130be0 (rcu_read_lock){....}-{1:2}, at: __bpf_trace_run kernel/trace/bpf_trace.c:2380 [inline]
#1: ffffffff8e130be0 (rcu_read_lock){....}-{1:2}, at: bpf_trace_run2+0x114/0x420 kernel/trace/bpf_trace.c:2420
#2: ffffc900098410d8 (&rb->spinlock){-.-.}-{2:2}, at: __bpf_ringbuf_reserve+0x211/0x4f0 kernel/bpf/ringbuf.c:424
#3: ffffffff8e130be0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:298 [inline]
#3: ffffffff8e130be0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:750 [inline]
#3: ffffffff8e130be0 (rcu_read_lock){....}-{1:2}, at: __bpf_trace_run kernel/trace/bpf_trace.c:2380 [inline]
#3: ffffffff8e130be0 (rcu_read_lock){....}-{1:2}, at: bpf_trace_run2+0x114/0x420 kernel/trace/bpf_trace.c:2420

stack backtrace:
CPU: 0 PID: 5063 Comm: strace-static-x Not tainted 6.8.0-rc7-syzkaller-gdf4793505abd #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/25/2024
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x1e7/0x2e0 lib/dump_stack.c:106
check_deadlock kernel/locking/lockdep.c:3062 [inline]
validate_chain+0x15c0/0x58e0 kernel/locking/lockdep.c:3856
__lock_acquire+0x1345/0x1fd0 kernel/locking/lockdep.c:5137
lock_acquire+0x1e3/0x530 kernel/locking/lockdep.c:5754
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
_raw_spin_lock_irqsave+0xd5/0x120 kernel/locking/spinlock.c:162
__bpf_ringbuf_reserve+0x211/0x4f0 kernel/bpf/ringbuf.c:424
____bpf_ringbuf_reserve kernel/bpf/ringbuf.c:459 [inline]
bpf_ringbuf_reserve+0x5c/0x70 kernel/bpf/ringbuf.c:451
bpf_prog_9efe54833449f08e+0x2d/0x47
bpf_dispatcher_nop_func include/linux/bpf.h:1231 [inline]
__bpf_prog_run include/linux/filter.h:651 [inline]
bpf_prog_run include/linux/filter.h:658 [inline]
__bpf_trace_run kernel/trace/bpf_trace.c:2381 [inline]
bpf_trace_run2+0x204/0x420 kernel/trace/bpf_trace.c:2420
__traceiter_contention_end+0x7b/0xb0 include/trace/events/lock.h:122
trace_contention_end+0xf6/0x120 include/trace/events/lock.h:122
__pv_queued_spin_lock_slowpath+0x939/0xc60 kernel/locking/qspinlock.c:560
pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:584 [inline]
queued_spin_lock_slowpath+0x42/0x50 arch/x86/include/asm/qspinlock.h:51
queued_spin_lock include/asm-generic/qspinlock.h:114 [inline]
do_raw_spin_lock+0x271/0x370 kernel/locking/spinlock_debug.c:116
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:111 [inline]
_raw_spin_lock_irqsave+0xe1/0x120 kernel/locking/spinlock.c:162
__bpf_ringbuf_reserve+0x211/0x4f0 kernel/bpf/ringbuf.c:424
____bpf_ringbuf_reserve kernel/bpf/ringbuf.c:459 [inline]
bpf_ringbuf_reserve+0x5c/0x70 kernel/bpf/ringbuf.c:451
bpf_prog_9efe54833449f08e+0x2d/0x47
bpf_dispatcher_nop_func include/linux/bpf.h:1231 [inline]
__bpf_prog_run include/linux/filter.h:651 [inline]
bpf_prog_run include/linux/filter.h:658 [inline]
__bpf_trace_run kernel/trace/bpf_trace.c:2381 [inline]
bpf_trace_run2+0x204/0x420 kernel/trace/bpf_trace.c:2420
__traceiter_contention_end+0x7b/0xb0 include/trace/events/lock.h:122
trace_contention_end+0xd7/0x100 include/trace/events/lock.h:122
__mutex_lock_common kernel/locking/mutex.c:617 [inline]
__mutex_lock+0x2e4/0xd70 kernel/locking/mutex.c:752
__pipe_lock fs/pipe.c:103 [inline]
pipe_write+0x1cc/0x1a40 fs/pipe.c:465
call_write_iter include/linux/fs.h:2087 [inline]
new_sync_write fs/read_write.c:497 [inline]
vfs_write+0xa81/0xcb0 fs/read_write.c:590
ksys_write+0x1a0/0x2c0 fs/read_write.c:643
do_syscall_64+0xf9/0x240
entry_SYSCALL_64_after_hwframe+0x6f/0x77
RIP: 0033:0x4e8593
Code: c7 c2 a8 ff ff ff f7 d8 64 89 02 48 c7 c0 ff ff ff ff eb b7 0f 1f 00 64 8b 04 25 18 00 00 00 85 c0 75 14 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 55 c3 0f 1f 40 00 48 83 ec 28 48 89 54 24 18
RSP: 002b:00007ffeda768928 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000000000012 RCX: 00000000004e8593
RDX: 0000000000000012 RSI: 0000000000817140 RDI: 0000000000000002
RBP: 0000000000817140 R08: 0000000000000010 R09: 0000000000000090
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000012
R13: 000000000063f460 R14: 0000000000000012 R15: 0000000000000001
</TASK>

---
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Next message: Alexei Starovoitov: "Re: [External] Re: [PATCH bpf-next v2 1/9] bpf: tracing: add support to record and check the accessed args"
Previous message: Johan Hovold: "Re: [PATCH] drm/msm/dp: move link_ready out of HPD event thread"
Next in thread: Jiri Olsa: "Re: [syzbot] [bpf?] possible deadlock in __bpf_ringbuf_reserve"
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