syzbot

======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.9.6420/24339 is trying to acquire lock:
ffffffff9af8cbd8 (nfnl_subsys_ipset){+.+.}-{4:4}, at: ip_set_nfnl_get_byindex+0x7c/0x290 net/netfilter/ipset/ip_set_core.c:909

but task is already holding lock:
ffff888026b1e0d8 (&nft_net->commit_mutex){+.+.}-{4:4}, at: nf_tables_valid_genid+0x35/0x140 net/netfilter/nf_tables_api.c:11499

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (&nft_net->commit_mutex){+.+.}-{4:4}:
       __mutex_lock_common kernel/locking/mutex.c:598 [inline]
       __mutex_lock+0x193/0x1060 kernel/locking/mutex.c:760
       nf_tables_dumpreset_set+0xcd/0x320 net/netfilter/nf_tables_api.c:6288
       netlink_dump+0x539/0xd30 net/netlink/af_netlink.c:2327
       __netlink_dump_start+0x6d6/0x990 net/netlink/af_netlink.c:2442
       netlink_dump_start include/linux/netlink.h:341 [inline]
       nft_netlink_dump_start_rcu+0x81/0x1f0 net/netfilter/nf_tables_api.c:1286
       nf_tables_getsetelem_reset+0x946/0xab0 net/netfilter/nf_tables_api.c:6604
       nfnetlink_rcv_msg+0x583/0x1200 net/netfilter/nfnetlink.c:290
       netlink_rcv_skb+0x158/0x420 net/netlink/af_netlink.c:2552
       nfnetlink_rcv+0x1b3/0x430 net/netfilter/nfnetlink.c:669
       netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline]
       netlink_unicast+0x5aa/0x870 net/netlink/af_netlink.c:1346
       netlink_sendmsg+0x8c8/0xdd0 net/netlink/af_netlink.c:1896
       sock_sendmsg_nosec net/socket.c:727 [inline]
       __sock_sendmsg net/socket.c:742 [inline]
       ____sys_sendmsg+0xa98/0xc70 net/socket.c:2630
       ___sys_sendmsg+0x134/0x1d0 net/socket.c:2684
       __sys_sendmsg+0x16d/0x220 net/socket.c:2716
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0xcd/0xfa0 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #1 (nlk_cb_mutex-NETFILTER){+.+.}-{4:4}:
       __mutex_lock_common kernel/locking/mutex.c:598 [inline]
       __mutex_lock+0x193/0x1060 kernel/locking/mutex.c:760
       __netlink_dump_start+0x150/0x990 net/netlink/af_netlink.c:2406
       netlink_dump_start include/linux/netlink.h:341 [inline]
       ip_set_dump+0x17f/0x210 net/netfilter/ipset/ip_set_core.c:1717
       nfnetlink_rcv_msg+0x9fc/0x1200 net/netfilter/nfnetlink.c:302
       netlink_rcv_skb+0x158/0x420 net/netlink/af_netlink.c:2552
       nfnetlink_rcv+0x1b3/0x430 net/netfilter/nfnetlink.c:669
       netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline]
       netlink_unicast+0x5aa/0x870 net/netlink/af_netlink.c:1346
       netlink_sendmsg+0x8c8/0xdd0 net/netlink/af_netlink.c:1896
       sock_sendmsg_nosec net/socket.c:727 [inline]
       __sock_sendmsg net/socket.c:742 [inline]
       ____sys_sendmsg+0xa98/0xc70 net/socket.c:2630
       ___sys_sendmsg+0x134/0x1d0 net/socket.c:2684
       __sys_sendmsg+0x16d/0x220 net/socket.c:2716
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0xcd/0xfa0 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #0 (nfnl_subsys_ipset){+.+.}-{4:4}:
       check_prev_add kernel/locking/lockdep.c:3165 [inline]
       check_prevs_add kernel/locking/lockdep.c:3284 [inline]
       validate_chain kernel/locking/lockdep.c:3908 [inline]
       __lock_acquire+0x126f/0x1c90 kernel/locking/lockdep.c:5237
       lock_acquire kernel/locking/lockdep.c:5868 [inline]
       lock_acquire+0x179/0x350 kernel/locking/lockdep.c:5825
       __mutex_lock_common kernel/locking/mutex.c:598 [inline]
       __mutex_lock+0x193/0x1060 kernel/locking/mutex.c:760
       ip_set_nfnl_get_byindex+0x7c/0x290 net/netfilter/ipset/ip_set_core.c:909
       set_target_v1_checkentry+0x1ac/0x570 net/netfilter/xt_set.c:313
       xt_check_target+0x27c/0xa40 net/netfilter/x_tables.c:1038
       nft_target_init+0x459/0x7d0 net/netfilter/nft_compat.c:267
       nf_tables_newexpr net/netfilter/nf_tables_api.c:3527 [inline]
       nf_tables_newrule+0xea9/0x28f0 net/netfilter/nf_tables_api.c:4358
       nfnetlink_rcv_batch+0x190d/0x2350 net/netfilter/nfnetlink.c:526
       nfnetlink_rcv_skb_batch net/netfilter/nfnetlink.c:649 [inline]
       nfnetlink_rcv+0x3c1/0x430 net/netfilter/nfnetlink.c:667
       netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline]
       netlink_unicast+0x5aa/0x870 net/netlink/af_netlink.c:1346
       netlink_sendmsg+0x8c8/0xdd0 net/netlink/af_netlink.c:1896
       sock_sendmsg_nosec net/socket.c:727 [inline]
       __sock_sendmsg net/socket.c:742 [inline]
       ____sys_sendmsg+0xa98/0xc70 net/socket.c:2630
       ___sys_sendmsg+0x134/0x1d0 net/socket.c:2684
       __sys_sendmsg+0x16d/0x220 net/socket.c:2716
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0xcd/0xfa0 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

other info that might help us debug this:

Chain exists of:
  nfnl_subsys_ipset --> nlk_cb_mutex-NETFILTER --> &nft_net->commit_mutex

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&nft_net->commit_mutex);
                               lock(nlk_cb_mutex-NETFILTER);
                               lock(&nft_net->commit_mutex);
  lock(nfnl_subsys_ipset);

 *** DEADLOCK ***

1 lock held by syz.9.6420/24339:
 #0: ffff888026b1e0d8 (&nft_net->commit_mutex){+.+.}-{4:4}, at: nf_tables_valid_genid+0x35/0x140 net/netfilter/nf_tables_api.c:11499

stack backtrace:
CPU: 3 UID: 0 PID: 24339 Comm: syz.9.6420 Not tainted syzkaller #0 PREEMPT(full) 
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+0x275/0x350 kernel/locking/lockdep.c:2043
 check_noncircular+0x14c/0x170 kernel/locking/lockdep.c:2175
 check_prev_add kernel/locking/lockdep.c:3165 [inline]
 check_prevs_add kernel/locking/lockdep.c:3284 [inline]
 validate_chain kernel/locking/lockdep.c:3908 [inline]
 __lock_acquire+0x126f/0x1c90 kernel/locking/lockdep.c:5237
 lock_acquire kernel/locking/lockdep.c:5868 [inline]
 lock_acquire+0x179/0x350 kernel/locking/lockdep.c:5825
 __mutex_lock_common kernel/locking/mutex.c:598 [inline]
 __mutex_lock+0x193/0x1060 kernel/locking/mutex.c:760
 ip_set_nfnl_get_byindex+0x7c/0x290 net/netfilter/ipset/ip_set_core.c:909
 set_target_v1_checkentry+0x1ac/0x570 net/netfilter/xt_set.c:313
 xt_check_target+0x27c/0xa40 net/netfilter/x_tables.c:1038
 nft_target_init+0x459/0x7d0 net/netfilter/nft_compat.c:267
 nf_tables_newexpr net/netfilter/nf_tables_api.c:3527 [inline]
 nf_tables_newrule+0xea9/0x28f0 net/netfilter/nf_tables_api.c:4358
 nfnetlink_rcv_batch+0x190d/0x2350 net/netfilter/nfnetlink.c:526
 nfnetlink_rcv_skb_batch net/netfilter/nfnetlink.c:649 [inline]
 nfnetlink_rcv+0x3c1/0x430 net/netfilter/nfnetlink.c:667
 netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline]
 netlink_unicast+0x5aa/0x870 net/netlink/af_netlink.c:1346
 netlink_sendmsg+0x8c8/0xdd0 net/netlink/af_netlink.c:1896
 sock_sendmsg_nosec net/socket.c:727 [inline]
 __sock_sendmsg net/socket.c:742 [inline]
 ____sys_sendmsg+0xa98/0xc70 net/socket.c:2630
 ___sys_sendmsg+0x134/0x1d0 net/socket.c:2684
 __sys_sendmsg+0x16d/0x220 net/socket.c:2716
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f24a538f6c9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f24a6265038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f24a55e5fa0 RCX: 00007f24a538f6c9
RDX: 0000000000000800 RSI: 0000200000000100 RDI: 0000000000000004
RBP: 00007f24a5411f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f24a55e6038 R14: 00007f24a55e5fa0 R15: 00007ffc70b4f688
 </TASK>
Cannot find add_set index 0 as target