syzbot


possible deadlock in htab_lru_map_delete_elem

Status: upstream: reported C repro on 2024/12/06 13:58
Subsystems: bpf
[Documentation on labels]
Reported-by: syzbot+0a26db48dcd6d80be6c0@syzkaller.appspotmail.com
First crash: 16d, last: 2d16h
Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [bpf?] possible deadlock in htab_lru_map_delete_elem 1 (2) 2024/12/06 18:59
Last patch testing requests (1)
Created Duration User Patch Repo Result
2024/12/18 21:59 14m retest repro upstream report log

Sample crash report:
======================================================
WARNING: possible circular locking dependency detected
6.13.0-rc1-syzkaller-00025-gfeffde684ac2 #0 Not tainted
------------------------------------------------------
syz-executor207/6807 is trying to acquire lock:
ffff88802632eca0 (&htab->lockdep_key#434){....}-{2:2}, at: htab_lock_bucket kernel/bpf/hashtab.c:167 [inline]
ffff88802632eca0 (&htab->lockdep_key#434){....}-{2:2}, at: htab_lru_map_delete_elem+0x1c8/0x790 kernel/bpf/hashtab.c:1484

but task is already holding lock:
ffff888031440e20 (&htab->lockdep_key#435){....}-{2:2}, at: htab_lock_bucket kernel/bpf/hashtab.c:167 [inline]
ffff888031440e20 (&htab->lockdep_key#435){....}-{2:2}, at: htab_lru_map_delete_elem+0x1c8/0x790 kernel/bpf/hashtab.c:1484

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&htab->lockdep_key#435){....}-{2:2}:
       __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
       _raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154
       htab_lock_bucket kernel/bpf/hashtab.c:167 [inline]
       htab_lru_map_delete_elem+0x1c8/0x790 kernel/bpf/hashtab.c:1484
       bpf_prog_2c29ac5cdc6b1842+0x43/0x47
       bpf_dispatcher_nop_func include/linux/bpf.h:1290 [inline]
       __bpf_prog_run include/linux/filter.h:701 [inline]
       bpf_prog_run include/linux/filter.h:708 [inline]
       __bpf_trace_run kernel/trace/bpf_trace.c:2351 [inline]
       bpf_trace_run2+0x231/0x590 kernel/trace/bpf_trace.c:2392
       __bpf_trace_contention_begin+0xca/0x110 include/trace/events/lock.h:95
       __traceiter_contention_begin+0x5a/0xa0 include/trace/events/lock.h:95
       __preempt_count_dec_and_test arch/x86/include/asm/preempt.h:94 [inline]
       class_preempt_notrace_destructor include/linux/preempt.h:481 [inline]
       trace_contention_begin.constprop.0+0xf3/0x170 include/trace/events/lock.h:95
       __pv_queued_spin_lock_slowpath+0x10b/0xc90 kernel/locking/qspinlock.c:402
       pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:584 [inline]
       queued_spin_lock_slowpath arch/x86/include/asm/qspinlock.h:51 [inline]
       queued_spin_lock include/asm-generic/qspinlock.h:114 [inline]
       do_raw_spin_lock+0x210/0x2c0 kernel/locking/spinlock_debug.c:116
       htab_lock_bucket kernel/bpf/hashtab.c:167 [inline]
       htab_lru_map_delete_elem+0x1c8/0x790 kernel/bpf/hashtab.c:1484
       bpf_prog_2c29ac5cdc6b1842+0x43/0x47
       bpf_dispatcher_nop_func include/linux/bpf.h:1290 [inline]
       __bpf_prog_run include/linux/filter.h:701 [inline]
       bpf_prog_run include/linux/filter.h:708 [inline]
       __bpf_trace_run kernel/trace/bpf_trace.c:2351 [inline]
       bpf_trace_run2+0x231/0x590 kernel/trace/bpf_trace.c:2392
       __bpf_trace_contention_begin+0xca/0x110 include/trace/events/lock.h:95
       __traceiter_contention_begin+0x5a/0xa0 include/trace/events/lock.h:95
       trace_contention_begin+0xd2/0x140 include/trace/events/lock.h:95
       __mutex_lock_common kernel/locking/mutex.c:587 [inline]
       __mutex_lock+0x1a8/0xa60 kernel/locking/mutex.c:735
       futex_cleanup_begin kernel/futex/core.c:1070 [inline]
       futex_exit_release+0x2a/0x220 kernel/futex/core.c:1122
       exit_mm_release+0x19/0x30 kernel/fork.c:1660
       exit_mm kernel/exit.c:543 [inline]
       do_exit+0x88b/0x2d70 kernel/exit.c:925
       do_group_exit+0xd3/0x2a0 kernel/exit.c:1087
       __do_sys_exit_group kernel/exit.c:1098 [inline]
       __se_sys_exit_group kernel/exit.c:1096 [inline]
       __x64_sys_exit_group+0x3e/0x50 kernel/exit.c:1096
       x64_sys_call+0x151f/0x1720 arch/x86/include/generated/asm/syscalls_64.h:232
       do_syscall_x64 arch/x86/entry/common.c:52 [inline]
       do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #0 (&htab->lockdep_key#434){....}-{2:2}:
       check_prev_add kernel/locking/lockdep.c:3161 [inline]
       check_prevs_add kernel/locking/lockdep.c:3280 [inline]
       validate_chain kernel/locking/lockdep.c:3904 [inline]
       __lock_acquire+0x249e/0x3c40 kernel/locking/lockdep.c:5226
       lock_acquire.part.0+0x11b/0x380 kernel/locking/lockdep.c:5849
       __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
       _raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154
       htab_lock_bucket kernel/bpf/hashtab.c:167 [inline]
       htab_lru_map_delete_elem+0x1c8/0x790 kernel/bpf/hashtab.c:1484
       bpf_prog_2c29ac5cdc6b1842+0x43/0x47
       bpf_dispatcher_nop_func include/linux/bpf.h:1290 [inline]
       __bpf_prog_run include/linux/filter.h:701 [inline]
       bpf_prog_run include/linux/filter.h:708 [inline]
       __bpf_trace_run kernel/trace/bpf_trace.c:2351 [inline]
       bpf_trace_run2+0x231/0x590 kernel/trace/bpf_trace.c:2392
       __bpf_trace_contention_begin+0xca/0x110 include/trace/events/lock.h:95
       __traceiter_contention_begin+0x5a/0xa0 include/trace/events/lock.h:95
       __preempt_count_dec_and_test arch/x86/include/asm/preempt.h:94 [inline]
       class_preempt_notrace_destructor include/linux/preempt.h:481 [inline]
       trace_contention_begin.constprop.0+0xf3/0x170 include/trace/events/lock.h:95
       __pv_queued_spin_lock_slowpath+0x10b/0xc90 kernel/locking/qspinlock.c:402
       pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:584 [inline]
       queued_spin_lock_slowpath arch/x86/include/asm/qspinlock.h:51 [inline]
       queued_spin_lock include/asm-generic/qspinlock.h:114 [inline]
       do_raw_spin_lock+0x210/0x2c0 kernel/locking/spinlock_debug.c:116
       htab_lock_bucket kernel/bpf/hashtab.c:167 [inline]
       htab_lru_map_delete_elem+0x1c8/0x790 kernel/bpf/hashtab.c:1484
       bpf_prog_2c29ac5cdc6b1842+0x43/0x47
       bpf_dispatcher_nop_func include/linux/bpf.h:1290 [inline]
       __bpf_prog_run include/linux/filter.h:701 [inline]
       bpf_prog_run include/linux/filter.h:708 [inline]
       __bpf_trace_run kernel/trace/bpf_trace.c:2351 [inline]
       bpf_trace_run2+0x231/0x590 kernel/trace/bpf_trace.c:2392
       __bpf_trace_contention_begin+0xca/0x110 include/trace/events/lock.h:95
       __traceiter_contention_begin+0x5a/0xa0 include/trace/events/lock.h:95
       trace_contention_begin+0xd2/0x140 include/trace/events/lock.h:95
       __mutex_lock_common kernel/locking/mutex.c:587 [inline]
       __mutex_lock+0x1a8/0xa60 kernel/locking/mutex.c:735
       uprobe_clear_state+0x4b/0x1a0 kernel/events/uprobes.c:1771
       __mmput+0x79/0x4c0 kernel/fork.c:1349
       mmput+0x62/0x70 kernel/fork.c:1375
       exit_mm kernel/exit.c:570 [inline]
       do_exit+0x9bf/0x2d70 kernel/exit.c:925
       do_group_exit+0xd3/0x2a0 kernel/exit.c:1087
       __do_sys_exit_group kernel/exit.c:1098 [inline]
       __se_sys_exit_group kernel/exit.c:1096 [inline]
       __x64_sys_exit_group+0x3e/0x50 kernel/exit.c:1096
       x64_sys_call+0x151f/0x1720 arch/x86/include/generated/asm/syscalls_64.h:232
       do_syscall_x64 arch/x86/entry/common.c:52 [inline]
       do_syscall_64+0xcd/0x250 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(&htab->lockdep_key#435);
                               lock(&htab->lockdep_key#434);
                               lock(&htab->lockdep_key#435);
  lock(&htab->lockdep_key#434);

 *** DEADLOCK ***

4 locks held by syz-executor207/6807:
 #0: ffffffff8e2d69e8 (delayed_uprobe_lock){+.+.}-{4:4}, at: uprobe_clear_state+0x4b/0x1a0 kernel/events/uprobes.c:1771
 #1: ffffffff8e1bb500 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:337 [inline]
 #1: ffffffff8e1bb500 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #1: ffffffff8e1bb500 (rcu_read_lock){....}-{1:3}, at: __bpf_trace_run kernel/trace/bpf_trace.c:2350 [inline]
 #1: ffffffff8e1bb500 (rcu_read_lock){....}-{1:3}, at: bpf_trace_run2+0x1c2/0x590 kernel/trace/bpf_trace.c:2392
 #2: ffff888031440e20 (&htab->lockdep_key#435){....}-{2:2}, at: htab_lock_bucket kernel/bpf/hashtab.c:167 [inline]
 #2: ffff888031440e20 (&htab->lockdep_key#435){....}-{2:2}, at: htab_lru_map_delete_elem+0x1c8/0x790 kernel/bpf/hashtab.c:1484
 #3: ffffffff8e1bb500 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:337 [inline]
 #3: ffffffff8e1bb500 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #3: ffffffff8e1bb500 (rcu_read_lock){....}-{1:3}, at: __bpf_trace_run kernel/trace/bpf_trace.c:2350 [inline]
 #3: ffffffff8e1bb500 (rcu_read_lock){....}-{1:3}, at: bpf_trace_run2+0x1c2/0x590 kernel/trace/bpf_trace.c:2392

stack backtrace:
CPU: 3 UID: 0 PID: 6807 Comm: syz-executor207 Not tainted 6.13.0-rc1-syzkaller-00025-gfeffde684ac2 #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
 print_circular_bug+0x419/0x5d0 kernel/locking/lockdep.c:2074
 check_noncircular+0x31a/0x400 kernel/locking/lockdep.c:2206
 check_prev_add kernel/locking/lockdep.c:3161 [inline]
 check_prevs_add kernel/locking/lockdep.c:3280 [inline]
 validate_chain kernel/locking/lockdep.c:3904 [inline]
 __lock_acquire+0x249e/0x3c40 kernel/locking/lockdep.c:5226
 lock_acquire.part.0+0x11b/0x380 kernel/locking/lockdep.c:5849
 __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
 _raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154
 htab_lock_bucket kernel/bpf/hashtab.c:167 [inline]
 htab_lru_map_delete_elem+0x1c8/0x790 kernel/bpf/hashtab.c:1484
 bpf_prog_2c29ac5cdc6b1842+0x43/0x47
 bpf_dispatcher_nop_func include/linux/bpf.h:1290 [inline]
 __bpf_prog_run include/linux/filter.h:701 [inline]
 bpf_prog_run include/linux/filter.h:708 [inline]
 __bpf_trace_run kernel/trace/bpf_trace.c:2351 [inline]
 bpf_trace_run2+0x231/0x590 kernel/trace/bpf_trace.c:2392
 __bpf_trace_contention_begin+0xca/0x110 include/trace/events/lock.h:95
 __traceiter_contention_begin+0x5a/0xa0 include/trace/events/lock.h:95
 __preempt_count_dec_and_test arch/x86/include/asm/preempt.h:94 [inline]
 class_preempt_notrace_destructor include/linux/preempt.h:481 [inline]
 trace_contention_begin.constprop.0+0xf3/0x170 include/trace/events/lock.h:95
 __pv_queued_spin_lock_slowpath+0x10b/0xc90 kernel/locking/qspinlock.c:402
 pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:584 [inline]
 queued_spin_lock_slowpath arch/x86/include/asm/qspinlock.h:51 [inline]
 queued_spin_lock include/asm-generic/qspinlock.h:114 [inline]
 do_raw_spin_lock+0x210/0x2c0 kernel/locking/spinlock_debug.c:116
 htab_lock_bucket kernel/bpf/hashtab.c:167 [inline]
 htab_lru_map_delete_elem+0x1c8/0x790 kernel/bpf/hashtab.c:1484
 bpf_prog_2c29ac5cdc6b1842+0x43/0x47
 bpf_dispatcher_nop_func include/linux/bpf.h:1290 [inline]
 __bpf_prog_run include/linux/filter.h:701 [inline]
 bpf_prog_run include/linux/filter.h:708 [inline]
 __bpf_trace_run kernel/trace/bpf_trace.c:2351 [inline]
 bpf_trace_run2+0x231/0x590 kernel/trace/bpf_trace.c:2392
 __bpf_trace_contention_begin+0xca/0x110 include/trace/events/lock.h:95
 __traceiter_contention_begin+0x5a/0xa0 include/trace/events/lock.h:95
 trace_contention_begin+0xd2/0x140 include/trace/events/lock.h:95
 __mutex_lock_common kernel/locking/mutex.c:587 [inline]
 __mutex_lock+0x1a8/0xa60 kernel/locking/mutex.c:735
 uprobe_clear_state+0x4b/0x1a0 kernel/events/uprobes.c:1771
 __mmput+0x79/0x4c0 kernel/fork.c:1349
 mmput+0x62/0x70 kernel/fork.c:1375
 exit_mm kernel/exit.c:570 [inline]
 do_exit+0x9bf/0x2d70 kernel/exit.c:925
 do_group_exit+0xd3/0x2a0 kernel/exit.c:1087
 __do_sys_exit_group kernel/exit.c:1098 [inline]
 __se_sys_exit_group kernel/exit.c:1096 [inline]
 __x64_sys_exit_group+0x3e/0x50 kernel/exit.c:1096
 x64_sys_call+0x151f/0x1720 arch/x86/include/generated/asm/syscalls_64.h:232
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fe3838cedf9
Code: Unable to access opcode bytes at 0x7fe3838cedcf.
RSP: 002b:00007ffd9c887888 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fe3838cedf9
RDX: 000000000000003c RSI: 00000000000000e7 RDI: 0000000000000000
RBP: 00007fe38395b390 R08: ffffffffffffffb0 R09: 00007ffd9c887910
R10: 00007ffd9c887910 R11: 0000000000000246 R12: 00007fe38395b390
R13: 0000000000000000 R14: 00007fe38395bf20 R15: 00007fe38389c900
 </TASK>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2024/12/04 21:46 upstream feffde684ac2 b50eb251 .config console log report syz / log C [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream possible deadlock in htab_lru_map_delete_elem
* Struck through repros no longer work on HEAD.