netlink: 48 bytes leftover after parsing attributes in process `syz.8.6539'. ====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Tainted: G L ------------------------------------------------------ syz.8.6539/2008 is trying to acquire lock: ffff888052e32cd8 (&nft_net->commit_mutex){+.+.}-{4:4}, at: nf_tables_dumpreset_rules+0x6f/0xa0 net/netfilter/nf_tables_api.c:3913 but task is already holding lock: ffff888025cb16f0 (nlk_cb_mutex-NETFILTER){+.+.}-{4:4}, at: __netlink_dump_start+0x150/0x990 net/netlink/af_netlink.c:2404 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (nlk_cb_mutex-NETFILTER){+.+.}-{4:4}: __mutex_lock_common kernel/locking/mutex.c:614 [inline] __mutex_lock+0x1aa/0x1ca0 kernel/locking/mutex.c:776 __netlink_dump_start+0x150/0x990 net/netlink/af_netlink.c:2404 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:2550 nfnetlink_rcv+0x1b3/0x430 net/netfilter/nfnetlink.c:669 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline] netlink_unicast+0x5aa/0x870 net/netlink/af_netlink.c:1344 netlink_sendmsg+0x8c8/0xdd0 net/netlink/af_netlink.c:1894 sock_sendmsg_nosec net/socket.c:727 [inline] __sock_sendmsg net/socket.c:742 [inline] ____sys_sendmsg+0xa5d/0xc30 net/socket.c:2592 ___sys_sendmsg+0x134/0x1d0 net/socket.c:2646 __sys_sendmsg+0x16d/0x220 net/socket.c:2678 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:83 [inline] __do_fast_syscall_32+0xe8/0x680 arch/x86/entry/syscall_32.c:307 do_fast_syscall_32+0x32/0x80 arch/x86/entry/syscall_32.c:332 entry_SYSENTER_compat_after_hwframe+0x84/0x8e -> #1 (nfnl_subsys_ipset){+.+.}-{4:4}: __mutex_lock_common kernel/locking/mutex.c:614 [inline] __mutex_lock+0x1aa/0x1ca0 kernel/locking/mutex.c:776 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:3550 [inline] nf_tables_newrule+0xedd/0x2910 net/netfilter/nf_tables_api.c:4419 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:1318 [inline] netlink_unicast+0x5aa/0x870 net/netlink/af_netlink.c:1344 netlink_sendmsg+0x8c8/0xdd0 net/netlink/af_netlink.c:1894 sock_sendmsg_nosec net/socket.c:727 [inline] __sock_sendmsg net/socket.c:742 [inline] ____sys_sendmsg+0xa5d/0xc30 net/socket.c:2592 ___sys_sendmsg+0x134/0x1d0 net/socket.c:2646 __sys_sendmsg+0x16d/0x220 net/socket.c:2678 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:83 [inline] __do_fast_syscall_32+0xe8/0x680 arch/x86/entry/syscall_32.c:307 do_fast_syscall_32+0x32/0x80 arch/x86/entry/syscall_32.c:332 entry_SYSENTER_compat_after_hwframe+0x84/0x8e -> #0 (&nft_net->commit_mutex){+.+.}-{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+0x1669/0x2890 kernel/locking/lockdep.c:5237 lock_acquire kernel/locking/lockdep.c:5868 [inline] lock_acquire+0x179/0x330 kernel/locking/lockdep.c:5825 __mutex_lock_common kernel/locking/mutex.c:614 [inline] __mutex_lock+0x1aa/0x1ca0 kernel/locking/mutex.c:776 nf_tables_dumpreset_rules+0x6f/0xa0 net/netfilter/nf_tables_api.c:3913 netlink_dump+0x539/0xd30 net/netlink/af_netlink.c:2325 __netlink_dump_start+0x6d6/0x990 net/netlink/af_netlink.c:2440 netlink_dump_start include/linux/netlink.h:341 [inline] nft_netlink_dump_start_rcu+0x81/0x1f0 net/netfilter/nf_tables_api.c:1309 nf_tables_getrule_reset+0x56b/0x6b0 net/netfilter/nf_tables_api.c:4053 nfnetlink_rcv_msg+0x583/0x1200 net/netfilter/nfnetlink.c:290 netlink_rcv_skb+0x158/0x420 net/netlink/af_netlink.c:2550 nfnetlink_rcv+0x1b3/0x430 net/netfilter/nfnetlink.c:669 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline] netlink_unicast+0x5aa/0x870 net/netlink/af_netlink.c:1344 netlink_sendmsg+0x8c8/0xdd0 net/netlink/af_netlink.c:1894 sock_sendmsg_nosec net/socket.c:727 [inline] __sock_sendmsg net/socket.c:742 [inline] ____sys_sendmsg+0xa5d/0xc30 net/socket.c:2592 ___sys_sendmsg+0x134/0x1d0 net/socket.c:2646 __sys_sendmsg+0x16d/0x220 net/socket.c:2678 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:83 [inline] __do_fast_syscall_32+0xe8/0x680 arch/x86/entry/syscall_32.c:307 do_fast_syscall_32+0x32/0x80 arch/x86/entry/syscall_32.c:332 entry_SYSENTER_compat_after_hwframe+0x84/0x8e 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.8.6539/2008: #0: ffff888025cb16f0 (nlk_cb_mutex-NETFILTER){+.+.}-{4:4}, at: __netlink_dump_start+0x150/0x990 net/netlink/af_netlink.c:2404 stack backtrace: CPU: 2 UID: 0 PID: 2008 Comm: syz.8.6539 Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014 Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120 print_circular_bug+0x275/0x340 kernel/locking/lockdep.c:2043 check_noncircular+0x146/0x160 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+0x1669/0x2890 kernel/locking/lockdep.c:5237 lock_acquire kernel/locking/lockdep.c:5868 [inline] lock_acquire+0x179/0x330 kernel/locking/lockdep.c:5825 __mutex_lock_common kernel/locking/mutex.c:614 [inline] __mutex_lock+0x1aa/0x1ca0 kernel/locking/mutex.c:776 nf_tables_dumpreset_rules+0x6f/0xa0 net/netfilter/nf_tables_api.c:3913 netlink_dump+0x539/0xd30 net/netlink/af_netlink.c:2325 __netlink_dump_start+0x6d6/0x990 net/netlink/af_netlink.c:2440 netlink_dump_start include/linux/netlink.h:341 [inline] nft_netlink_dump_start_rcu+0x81/0x1f0 net/netfilter/nf_tables_api.c:1309 nf_tables_getrule_reset+0x56b/0x6b0 net/netfilter/nf_tables_api.c:4053 nfnetlink_rcv_msg+0x583/0x1200 net/netfilter/nfnetlink.c:290 netlink_rcv_skb+0x158/0x420 net/netlink/af_netlink.c:2550 nfnetlink_rcv+0x1b3/0x430 net/netfilter/nfnetlink.c:669 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline] netlink_unicast+0x5aa/0x870 net/netlink/af_netlink.c:1344 netlink_sendmsg+0x8c8/0xdd0 net/netlink/af_netlink.c:1894 sock_sendmsg_nosec net/socket.c:727 [inline] __sock_sendmsg net/socket.c:742 [inline] ____sys_sendmsg+0xa5d/0xc30 net/socket.c:2592 ___sys_sendmsg+0x134/0x1d0 net/socket.c:2646 __sys_sendmsg+0x16d/0x220 net/socket.c:2678 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:83 [inline] __do_fast_syscall_32+0xe8/0x680 arch/x86/entry/syscall_32.c:307 do_fast_syscall_32+0x32/0x80 arch/x86/entry/syscall_32.c:332 entry_SYSENTER_compat_after_hwframe+0x84/0x8e RIP: 0023:0xf702d579 Code: b8 01 10 06 03 74 b4 01 10 07 03 74 b0 01 10 08 03 74 d8 01 00 00 00 00 00 00 00 00 00 00 00 00 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 8d b4 26 00 00 00 00 8d b4 26 00 00 00 00 RSP: 002b:00000000f4f9f55c EFLAGS: 00000296 ORIG_RAX: 0000000000000172 RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000080000240 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000296 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 ---------------- Code disassembly (best guess), 2 bytes skipped: 0: 10 06 adc %al,(%rsi) 2: 03 74 b4 01 add 0x1(%rsp,%rsi,4),%esi 6: 10 07 adc %al,(%rdi) 8: 03 74 b0 01 add 0x1(%rax,%rsi,4),%esi c: 10 08 adc %cl,(%rax) e: 03 74 d8 01 add 0x1(%rax,%rbx,8),%esi 1e: 00 51 52 add %dl,0x52(%rcx) 21: 55 push %rbp 22: 89 e5 mov %esp,%ebp 24: 0f 34 sysenter 26: cd 80 int $0x80 * 28: 5d pop %rbp <-- trapping instruction 29: 5a pop %rdx 2a: 59 pop %rcx 2b: c3 ret 2c: 90 nop 2d: 90 nop 2e: 90 nop 2f: 90 nop 30: 8d b4 26 00 00 00 00 lea 0x0(%rsi,%riz,1),%esi 37: 8d b4 26 00 00 00 00 lea 0x0(%rsi,%riz,1),%esi