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| Kernel | Title | Rank 🛈 | Repro | Cause bisect | Fix bisect | Count | Last | Reported | Patched | Status |
|---|---|---|---|---|---|---|---|---|---|---|
| linux-6.1 | possible deadlock in nf_tables_dumpreset_obj | 4 | 3 | 17h05m | 2d18h | 0/3 | upstream: reported on 2026/03/26 12:38 | |||
| upstream | possible deadlock in nf_tables_dumpreset_obj netfilter | 4 | 1 | 103d | 99d | 28/29 | upstream: reported on 2025/12/20 00:58 |
netlink: 4 bytes leftover after parsing attributes in process `syz.0.4429'.
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.0.4429/19074 is trying to acquire lock:
ffff888050e096b8 (&nft_net->commit_mutex){+.+.}-{3:3}, at: nf_tables_dumpreset_obj+0x72/0xa0 net/netfilter/nf_tables_api.c:7994
but task is already holding lock:
ffff888057790690 (nlk_cb_mutex-NETFILTER){+.+.}-{3:3}, at: __netlink_dump_start+0xf4/0x810 net/netlink/af_netlink.c:2336
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #2 (nlk_cb_mutex-NETFILTER){+.+.}-{3:3}:
__mutex_lock_common kernel/locking/mutex.c:603 [inline]
__mutex_lock+0x136/0xcc0 kernel/locking/mutex.c:747
__netlink_dump_start+0xf4/0x810 net/netlink/af_netlink.c:2336
netlink_dump_start include/linux/netlink.h:338 [inline]
ip_set_dump+0x15c/0x1f0 net/netfilter/ipset/ip_set_core.c:1717
nfnetlink_rcv_msg+0xbf0/0x12b0 net/netfilter/nfnetlink.c:302
netlink_rcv_skb+0x241/0x4d0 net/netlink/af_netlink.c:2545
nfnetlink_rcv+0x2c9/0x24a0 net/netfilter/nfnetlink.c:659
netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline]
netlink_unicast+0x751/0x8d0 net/netlink/af_netlink.c:1346
netlink_sendmsg+0x8d0/0xbf0 net/netlink/af_netlink.c:1894
sock_sendmsg_nosec net/socket.c:730 [inline]
__sock_sendmsg net/socket.c:745 [inline]
____sys_sendmsg+0x5ba/0x960 net/socket.c:2594
___sys_sendmsg+0x2a6/0x360 net/socket.c:2648
__sys_sendmsg net/socket.c:2677 [inline]
__do_sys_sendmsg net/socket.c:2686 [inline]
__se_sys_sendmsg+0x1c2/0x2b0 net/socket.c:2684
do_syscall_x64 arch/x86/entry/common.c:46 [inline]
do_syscall_64+0x55/0xa0 arch/x86/entry/common.c:76
entry_SYSCALL_64_after_hwframe+0x68/0xd2
-> #1 (nfnl_subsys_ipset){+.+.}-{3:3}:
__mutex_lock_common kernel/locking/mutex.c:603 [inline]
__mutex_lock+0x136/0xcc0 kernel/locking/mutex.c:747
ip_set_nfnl_get_byindex+0x67/0x230 net/netfilter/ipset/ip_set_core.c:909
set_match_v1_checkentry+0x71/0x230 net/netfilter/xt_set.c:139
xt_check_match+0x429/0xaf0 net/netfilter/x_tables.c:523
__nft_match_init+0x67a/0x8d0 net/netfilter/nft_compat.c:522
nf_tables_newexpr net/netfilter/nf_tables_api.c:3307 [inline]
nf_tables_newrule+0x176c/0x2880 net/netfilter/nf_tables_api.c:4140
nfnetlink_rcv_batch net/netfilter/nfnetlink.c:519 [inline]
nfnetlink_rcv_skb_batch net/netfilter/nfnetlink.c:639 [inline]
nfnetlink_rcv+0x113e/0x24a0 net/netfilter/nfnetlink.c:657
netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline]
netlink_unicast+0x751/0x8d0 net/netlink/af_netlink.c:1346
netlink_sendmsg+0x8d0/0xbf0 net/netlink/af_netlink.c:1894
sock_sendmsg_nosec net/socket.c:730 [inline]
__sock_sendmsg net/socket.c:745 [inline]
____sys_sendmsg+0x5ba/0x960 net/socket.c:2594
___sys_sendmsg+0x2a6/0x360 net/socket.c:2648
__sys_sendmsg net/socket.c:2677 [inline]
__do_sys_sendmsg net/socket.c:2686 [inline]
__se_sys_sendmsg+0x1c2/0x2b0 net/socket.c:2684
do_syscall_x64 arch/x86/entry/common.c:46 [inline]
do_syscall_64+0x55/0xa0 arch/x86/entry/common.c:76
entry_SYSCALL_64_after_hwframe+0x68/0xd2
-> #0 (&nft_net->commit_mutex){+.+.}-{3:3}:
check_prev_add kernel/locking/lockdep.c:3134 [inline]
check_prevs_add kernel/locking/lockdep.c:3253 [inline]
validate_chain kernel/locking/lockdep.c:3869 [inline]
__lock_acquire+0x2df1/0x7d40 kernel/locking/lockdep.c:5137
lock_acquire+0x19e/0x420 kernel/locking/lockdep.c:5754
__mutex_lock_common kernel/locking/mutex.c:603 [inline]
__mutex_lock+0x136/0xcc0 kernel/locking/mutex.c:747
nf_tables_dumpreset_obj+0x72/0xa0 net/netfilter/nf_tables_api.c:7994
netlink_dump+0x747/0xe50 net/netlink/af_netlink.c:2264
__netlink_dump_start+0x5f1/0x810 net/netlink/af_netlink.c:2372
netlink_dump_start include/linux/netlink.h:338 [inline]
nft_netlink_dump_start_rcu+0xdb/0x1a0 net/netfilter/nf_tables_api.c:1124
nf_tables_getobj_reset+0x1e1/0x630 net/netfilter/nf_tables_api.c:8129
nfnetlink_rcv_msg+0x8a4/0x12b0 net/netfilter/nfnetlink.c:290
netlink_rcv_skb+0x241/0x4d0 net/netlink/af_netlink.c:2545
nfnetlink_rcv+0x2c9/0x24a0 net/netfilter/nfnetlink.c:659
netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline]
netlink_unicast+0x751/0x8d0 net/netlink/af_netlink.c:1346
netlink_sendmsg+0x8d0/0xbf0 net/netlink/af_netlink.c:1894
sock_sendmsg_nosec net/socket.c:730 [inline]
__sock_sendmsg net/socket.c:745 [inline]
____sys_sendmsg+0x5ba/0x960 net/socket.c:2594
___sys_sendmsg+0x2a6/0x360 net/socket.c:2648
__sys_sendmsg net/socket.c:2677 [inline]
__do_sys_sendmsg net/socket.c:2686 [inline]
__se_sys_sendmsg+0x1c2/0x2b0 net/socket.c:2684
do_syscall_x64 arch/x86/entry/common.c:46 [inline]
do_syscall_64+0x55/0xa0 arch/x86/entry/common.c:76
entry_SYSCALL_64_after_hwframe+0x68/0xd2
other info that might help us debug this:
Chain exists of:
&nft_net->commit_mutex --> nfnl_subsys_ipset --> nlk_cb_mutex-NETFILTER
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(nlk_cb_mutex-NETFILTER);
lock(nfnl_subsys_ipset);
lock(nlk_cb_mutex-NETFILTER);
lock(&nft_net->commit_mutex);
*** DEADLOCK ***
1 lock held by syz.0.4429/19074:
#0: ffff888057790690 (nlk_cb_mutex-NETFILTER){+.+.}-{3:3}, at: __netlink_dump_start+0xf4/0x810 net/netlink/af_netlink.c:2336
stack backtrace:
CPU: 1 PID: 19074 Comm: syz.0.4429 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
Call Trace:
<TASK>
dump_stack_lvl+0x18c/0x250 lib/dump_stack.c:106
check_noncircular+0x2fc/0x400 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 kernel/locking/lockdep.c:3869 [inline]
__lock_acquire+0x2df1/0x7d40 kernel/locking/lockdep.c:5137
lock_acquire+0x19e/0x420 kernel/locking/lockdep.c:5754
__mutex_lock_common kernel/locking/mutex.c:603 [inline]
__mutex_lock+0x136/0xcc0 kernel/locking/mutex.c:747
nf_tables_dumpreset_obj+0x72/0xa0 net/netfilter/nf_tables_api.c:7994
netlink_dump+0x747/0xe50 net/netlink/af_netlink.c:2264
__netlink_dump_start+0x5f1/0x810 net/netlink/af_netlink.c:2372
netlink_dump_start include/linux/netlink.h:338 [inline]
nft_netlink_dump_start_rcu+0xdb/0x1a0 net/netfilter/nf_tables_api.c:1124
nf_tables_getobj_reset+0x1e1/0x630 net/netfilter/nf_tables_api.c:8129
nfnetlink_rcv_msg+0x8a4/0x12b0 net/netfilter/nfnetlink.c:290
netlink_rcv_skb+0x241/0x4d0 net/netlink/af_netlink.c:2545
nfnetlink_rcv+0x2c9/0x24a0 net/netfilter/nfnetlink.c:659
netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline]
netlink_unicast+0x751/0x8d0 net/netlink/af_netlink.c:1346
netlink_sendmsg+0x8d0/0xbf0 net/netlink/af_netlink.c:1894
sock_sendmsg_nosec net/socket.c:730 [inline]
__sock_sendmsg net/socket.c:745 [inline]
____sys_sendmsg+0x5ba/0x960 net/socket.c:2594
___sys_sendmsg+0x2a6/0x360 net/socket.c:2648
__sys_sendmsg net/socket.c:2677 [inline]
__do_sys_sendmsg net/socket.c:2686 [inline]
__se_sys_sendmsg+0x1c2/0x2b0 net/socket.c:2684
do_syscall_x64 arch/x86/entry/common.c:46 [inline]
do_syscall_64+0x55/0xa0 arch/x86/entry/common.c:76
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fca2bb9c799
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fca2ca13028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fca2be15fa0 RCX: 00007fca2bb9c799
RDX: 0000000024040808 RSI: 0000200000000180 RDI: 0000000000000003
RBP: 00007fca2bc32c99 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fca2be16038 R14: 00007fca2be15fa0 R15: 00007ffd39cc5b38
</TASK>
| Time | Kernel | Commit | Syzkaller | Config | Log | Report | Syz repro | C repro | VM info | Assets (help?) | Manager | Title |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 2026/03/27 14:22 | linux-6.6.y | c09fbcd31ae6 | 74a13a23 | .config | console log | report | info | [disk image] [vmlinux] [kernel image] | ci2-linux-6-6-kasan | possible deadlock in nf_tables_dumpreset_obj |