On Tue, Mar 12, 2024 at 10:02:27PM +0100, Jiri Olsa wrote: > On Tue, Mar 12, 2024 at 09:41:26AM -0700, syzbot wrote: > > 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] > > hum, scratching my head how this could passed through the prog->active check, nah could be 2 instances of the same program, got confused by the tag trace_contention_end __bpf_trace_run(prog1) bpf_prog_9efe54833449f08e bpf_ringbuf_reserve trace_contention_end __bpf_trace_run(prog1) prog1->active check fails __bpf_trace_run(prog2) bpf_prog_9efe54833449f08e bpf_ringbuf_reserve lockup we had similar issue in [1] and we replaced the lock with extra buffers, not sure that's possible in bpf_ringbuf_reserve jirka [1] e2bb9e01d589 bpf: Remove trace_printk_lock > will try to reproduce > > jirka > > > 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> > > > > > > --- > > 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 syzbot to run the reproducer, reply with: > > #syz test: git://repo/address.git branch-or-commit-hash > > If you attach or paste a git patch, syzbot will apply it before testing. > > > > 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
