syzbot


possible deadlock in htab_lock_bucket

Status: upstream: reported C repro on 2024/04/17 13:40
Bug presence: origin:upstream
[Documentation on labels]
Reported-by: syzbot+44ec6afbbc9b9c66b458@syzkaller.appspotmail.com
First crash: 68d, last: 32d
Bug presence (1)
Date Name Commit Repro Result
2024/05/04 upstream (ToT) 7367539ad4b0 C [report] possible deadlock in htab_lock_bucket
Fix bisection attempts (1)
Created Duration User Patch Repo Result
2024/05/22 21:38 2h48m bisect fix linux-6.1.y job log (0) log

Sample crash report:
======================================================
WARNING: possible circular locking dependency detected
6.1.87-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor242/3557 is trying to acquire lock:
ffff888013f5eca0 (&htab->lockdep_key#13){....}-{2:2}, at: htab_lock_bucket+0x1a0/0x360 kernel/bpf/hashtab.c:166

but task is already holding lock:
ffff88807b96aaa0 (&htab->lockdep_key#14){....}-{2:2}, at: htab_lock_bucket+0x1a0/0x360 kernel/bpf/hashtab.c:166

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&htab->lockdep_key#14){....}-{2:2}:
       lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5662
       __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
       _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:154
       htab_lock_bucket+0x1a0/0x360 kernel/bpf/hashtab.c:166
       htab_map_delete_elem+0x1d5/0x6b0 kernel/bpf/hashtab.c:1399
       bpf_prog_2c29ac5cdc6b1842+0x3a/0x3e
       bpf_dispatcher_nop_func include/linux/bpf.h:989 [inline]
       __bpf_prog_run include/linux/filter.h:596 [inline]
       bpf_prog_run include/linux/filter.h:610 [inline]
       __bpf_trace_run kernel/trace/bpf_trace.c:2273 [inline]
       bpf_trace_run2+0x361/0x410 kernel/trace/bpf_trace.c:2312
       __traceiter_contention_end+0x74/0xa0 include/trace/events/lock.h:122
       trace_contention_end+0x14c/0x190 include/trace/events/lock.h:122
       __pv_queued_spin_lock_slowpath+0x935/0xc50 kernel/locking/qspinlock.c:560
       pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:591 [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+0x269/0x370 kernel/locking/spinlock_debug.c:115
       htab_lock_bucket+0x1a0/0x360 kernel/bpf/hashtab.c:166
       htab_map_delete_elem+0x1d5/0x6b0 kernel/bpf/hashtab.c:1399
       bpf_prog_2c29ac5cdc6b1842+0x3a/0x3e
       bpf_dispatcher_nop_func include/linux/bpf.h:989 [inline]
       __bpf_prog_run include/linux/filter.h:596 [inline]
       bpf_prog_run include/linux/filter.h:610 [inline]
       __bpf_trace_run kernel/trace/bpf_trace.c:2273 [inline]
       bpf_trace_run2+0x361/0x410 kernel/trace/bpf_trace.c:2312
       __traceiter_contention_end+0x74/0xa0 include/trace/events/lock.h:122
       trace_contention_end+0x12f/0x170 include/trace/events/lock.h:122
       __mutex_lock_common kernel/locking/mutex.c:612 [inline]
       __mutex_lock+0x2ed/0xd80 kernel/locking/mutex.c:747
       nf_sockopt_find net/netfilter/nf_sockopt.c:67 [inline]
       nf_getsockopt+0x32/0x2b0 net/netfilter/nf_sockopt.c:113
       ip_getsockopt+0x21a/0x2d0 net/ipv4/ip_sockglue.c:1826
       tcp_getsockopt+0x15c/0x1c0 net/ipv4/tcp.c:4445
       __sys_getsockopt+0x2b2/0x5d0 net/socket.c:2327
       __do_sys_getsockopt net/socket.c:2342 [inline]
       __se_sys_getsockopt net/socket.c:2339 [inline]
       __x64_sys_getsockopt+0xb1/0xc0 net/socket.c:2339
       do_syscall_x64 arch/x86/entry/common.c:51 [inline]
       do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:81
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

-> #0 (&htab->lockdep_key#13){....}-{2:2}:
       check_prev_add kernel/locking/lockdep.c:3090 [inline]
       check_prevs_add kernel/locking/lockdep.c:3209 [inline]
       validate_chain+0x1661/0x5950 kernel/locking/lockdep.c:3825
       __lock_acquire+0x125b/0x1f80 kernel/locking/lockdep.c:5049
       lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5662
       __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
       _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:154
       htab_lock_bucket+0x1a0/0x360 kernel/bpf/hashtab.c:166
       htab_map_delete_elem+0x1d5/0x6b0 kernel/bpf/hashtab.c:1399
       bpf_prog_2c29ac5cdc6b1842+0x3a/0x3e
       bpf_dispatcher_nop_func include/linux/bpf.h:989 [inline]
       __bpf_prog_run include/linux/filter.h:596 [inline]
       bpf_prog_run include/linux/filter.h:610 [inline]
       __bpf_trace_run kernel/trace/bpf_trace.c:2273 [inline]
       bpf_trace_run2+0x361/0x410 kernel/trace/bpf_trace.c:2312
       __traceiter_contention_end+0x74/0xa0 include/trace/events/lock.h:122
       trace_contention_end+0x14c/0x190 include/trace/events/lock.h:122
       __pv_queued_spin_lock_slowpath+0x935/0xc50 kernel/locking/qspinlock.c:560
       pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:591 [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+0x269/0x370 kernel/locking/spinlock_debug.c:115
       htab_lock_bucket+0x1a0/0x360 kernel/bpf/hashtab.c:166
       htab_map_delete_elem+0x1d5/0x6b0 kernel/bpf/hashtab.c:1399
       bpf_prog_2c29ac5cdc6b1842+0x3a/0x3e
       bpf_dispatcher_nop_func include/linux/bpf.h:989 [inline]
       __bpf_prog_run include/linux/filter.h:596 [inline]
       bpf_prog_run include/linux/filter.h:610 [inline]
       __bpf_trace_run kernel/trace/bpf_trace.c:2273 [inline]
       bpf_trace_run2+0x361/0x410 kernel/trace/bpf_trace.c:2312
       __traceiter_contention_end+0x74/0xa0 include/trace/events/lock.h:122
       trace_contention_end+0x12f/0x170 include/trace/events/lock.h:122
       __mutex_lock_common kernel/locking/mutex.c:612 [inline]
       __mutex_lock+0x2ed/0xd80 kernel/locking/mutex.c:747
       xt_find_table_lock+0x48/0x3a0 net/netfilter/x_tables.c:1242
       xt_request_find_table_lock+0x22/0xf0 net/netfilter/x_tables.c:1284
       get_info net/ipv4/netfilter/ip_tables.c:965 [inline]
       do_ipt_get_ctl+0x872/0x1890 net/ipv4/netfilter/ip_tables.c:1661
       nf_getsockopt+0x28e/0x2b0 net/netfilter/nf_sockopt.c:116
       ip_getsockopt+0x21a/0x2d0 net/ipv4/ip_sockglue.c:1826
       tcp_getsockopt+0x15c/0x1c0 net/ipv4/tcp.c:4445
       __sys_getsockopt+0x2b2/0x5d0 net/socket.c:2327
       __do_sys_getsockopt net/socket.c:2342 [inline]
       __se_sys_getsockopt net/socket.c:2339 [inline]
       __x64_sys_getsockopt+0xb1/0xc0 net/socket.c:2339
       do_syscall_x64 arch/x86/entry/common.c:51 [inline]
       do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:81
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&htab->lockdep_key#14);
                               lock(&htab->lockdep_key#13);
                               lock(&htab->lockdep_key#14);
  lock(&htab->lockdep_key#13);

 *** DEADLOCK ***

4 locks held by syz-executor242/3557:
 #0: ffff8880295a8308 (&xt[i].mutex){+.+.}-{3:3}, at: xt_find_table_lock+0x48/0x3a0 net/netfilter/x_tables.c:1242
 #1: ffffffff8d12ac80 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
 #1: ffffffff8d12ac80 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline]
 #1: ffffffff8d12ac80 (rcu_read_lock){....}-{1:2}, at: __bpf_trace_run kernel/trace/bpf_trace.c:2272 [inline]
 #1: ffffffff8d12ac80 (rcu_read_lock){....}-{1:2}, at: bpf_trace_run2+0x110/0x410 kernel/trace/bpf_trace.c:2312
 #2: ffff88807b96aaa0 (&htab->lockdep_key#14){....}-{2:2}, at: htab_lock_bucket+0x1a0/0x360 kernel/bpf/hashtab.c:166
 #3: ffffffff8d12ac80 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
 #3: ffffffff8d12ac80 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline]
 #3: ffffffff8d12ac80 (rcu_read_lock){....}-{1:2}, at: __bpf_trace_run kernel/trace/bpf_trace.c:2272 [inline]
 #3: ffffffff8d12ac80 (rcu_read_lock){....}-{1:2}, at: bpf_trace_run2+0x110/0x410 kernel/trace/bpf_trace.c:2312

stack backtrace:
CPU: 1 PID: 3557 Comm: syz-executor242 Not tainted 6.1.87-syzkaller #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+0x1e3/0x2cb lib/dump_stack.c:106
 check_noncircular+0x2fa/0x3b0 kernel/locking/lockdep.c:2170
 check_prev_add kernel/locking/lockdep.c:3090 [inline]
 check_prevs_add kernel/locking/lockdep.c:3209 [inline]
 validate_chain+0x1661/0x5950 kernel/locking/lockdep.c:3825
 __lock_acquire+0x125b/0x1f80 kernel/locking/lockdep.c:5049
 lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5662
 __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
 _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:154
 htab_lock_bucket+0x1a0/0x360 kernel/bpf/hashtab.c:166
 htab_map_delete_elem+0x1d5/0x6b0 kernel/bpf/hashtab.c:1399
 bpf_prog_2c29ac5cdc6b1842+0x3a/0x3e
 bpf_dispatcher_nop_func include/linux/bpf.h:989 [inline]
 __bpf_prog_run include/linux/filter.h:596 [inline]
 bpf_prog_run include/linux/filter.h:610 [inline]
 __bpf_trace_run kernel/trace/bpf_trace.c:2273 [inline]
 bpf_trace_run2+0x361/0x410 kernel/trace/bpf_trace.c:2312
 __traceiter_contention_end+0x74/0xa0 include/trace/events/lock.h:122
 trace_contention_end+0x14c/0x190 include/trace/events/lock.h:122
 __pv_queued_spin_lock_slowpath+0x935/0xc50 kernel/locking/qspinlock.c:560
 pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:591 [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+0x269/0x370 kernel/locking/spinlock_debug.c:115
 htab_lock_bucket+0x1a0/0x360 kernel/bpf/hashtab.c:166
 htab_map_delete_elem+0x1d5/0x6b0 kernel/bpf/hashtab.c:1399
 bpf_prog_2c29ac5cdc6b1842+0x3a/0x3e
 bpf_dispatcher_nop_func include/linux/bpf.h:989 [inline]
 __bpf_prog_run include/linux/filter.h:596 [inline]
 bpf_prog_run include/linux/filter.h:610 [inline]
 __bpf_trace_run kernel/trace/bpf_trace.c:2273 [inline]
 bpf_trace_run2+0x361/0x410 kernel/trace/bpf_trace.c:2312
 __traceiter_contention_end+0x74/0xa0 include/trace/events/lock.h:122
 trace_contention_end+0x12f/0x170 include/trace/events/lock.h:122
 __mutex_lock_common kernel/locking/mutex.c:612 [inline]
 __mutex_lock+0x2ed/0xd80 kernel/locking/mutex.c:747
 xt_find_table_lock+0x48/0x3a0 net/netfilter/x_tables.c:1242
 xt_request_find_table_lock+0x22/0xf0 net/netfilter/x_tables.c:1284
 get_info net/ipv4/netfilter/ip_tables.c:965 [inline]
 do_ipt_get_ctl+0x872/0x1890 net/ipv4/netfilter/ip_tables.c:1661
 nf_getsockopt+0x28e/0x2b0 net/netfilter/nf_sockopt.c:116
 ip_getsockopt+0x21a/0x2d0 net/ipv4/ip_sockglue.c:1826
 tcp_getsockopt+0x15c/0x1c0 net/ipv4/tcp.c:4445
 __sys_getsockopt+0x2b2/0x5d0 net/socket.c:2327
 __do_sys_getsockopt net/socket.c:2342 [inline]
 __se_sys_getsockopt net/socket.c:2339 [inline]
 __x64_sys_getsockopt+0xb1/0xc0 net/socket.c:2339
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f617160ba4a
Code: c4 c1 e0 1a 0d 00 00 04 00 89 01 e9 e0 fe ff ff e8 0b 05 00 00 66 2e 0f 1f 84 00 00 00 00 00 90 49 89 ca b8 37 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 06 c3 0f 1f 44 00 00 48 c7 c2 b0 ff ff ff f7
RSP: 002b:00007ffcc07e9c48 EFLAGS: 00000242 ORIG_RAX: 0000000000000037
RAX: ffffffffffffffda RBX: 00007ffcc07e9c70 RCX: 00007f617160ba4a
RDX: 0000000000000040 RSI: 0000000000000000 RDI: 0000000000000003
RBP: 0000000000000003 R08: 00007ffcc07e9c6c R09: 00007ffcc07ea176
R10: 00007ffcc07e9c70 R11: 0000000000000242 R12: 00007f6171690440
R13: 00007f6171691f40 R14: 00007ffcc07e9c6c R15: 0000000000000000
 </TASK>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2024/04/17 13:39 linux-6.1.y 6741e066ec76 18f6e127 .config console log report syz C [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-perf possible deadlock in htab_lock_bucket
* Struck through repros no longer work on HEAD.