------------[ cut here ]------------ refcount_t: underflow; use-after-free. WARNING: lib/refcount.c:28 at refcount_warn_saturate+0xf4/0x130 lib/refcount.c:28, CPU#3: syz.0.1764/12782 Modules linked in: CPU: 3 UID: 0 PID: 12782 Comm: syz.0.1764 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 04/01/2014 RIP: 0010:refcount_warn_saturate+0xf4/0x130 lib/refcount.c:28 Code: cc e8 70 f9 0e fd 48 8d 3d 59 b9 e8 0b 67 48 0f b9 3a e8 5f f9 0e fd 5b 5d e9 d8 93 94 06 e8 53 f9 0e fd 48 8d 3d 4c b9 e8 0b <67> 48 0f b9 3a e8 42 f9 0e fd 5b 5d c3 cc cc cc cc e8 36 f9 0e fd RSP: 0018:ffffc900054ff120 EFLAGS: 00010293 RAX: 0000000000000000 RBX: ffff88803bf3ef00 RCX: ffffffff84f9b6bb RDX: ffff88802cdc4a00 RSI: ffffffff84f9b74d RDI: ffffffff90e270a0 RBP: 0000000000000003 R08: 0000000000000005 R09: 0000000000000004 R10: 0000000000000003 R11: 0000000000000000 R12: ffff88803bf3ef00 R13: ffffffff8a05bb60 R14: 0000000000000000 R15: 0000000000000018 FS: 00007f7276fc56c0(0000) GS:ffff8880d666a000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f7276fc4ff8 CR3: 0000000039e81000 CR4: 0000000000352ef0 Call Trace: __refcount_sub_and_test include/linux/refcount.h:400 [inline] __refcount_dec_and_test include/linux/refcount.h:432 [inline] refcount_dec_and_test include/linux/refcount.h:450 [inline] sock_put include/net/sock.h:2009 [inline] sk_common_release+0x260/0x370 net/core/sock.c:4024 inet_release+0xed/0x200 net/ipv4/af_inet.c:442 __sock_release net/socket.c:722 [inline] sock_release+0x91/0x1c0 net/socket.c:750 rxe_release_udp_tunnel drivers/infiniband/sw/rxe/rxe_net.c:294 [inline] rxe_sock_put+0xae/0x130 drivers/infiniband/sw/rxe/rxe_net.c:639 rxe_net_del+0x83/0x120 drivers/infiniband/sw/rxe/rxe_net.c:660 rxe_dellink+0x15/0x20 drivers/infiniband/sw/rxe/rxe.c:254 nldev_dellink+0x289/0x3c0 drivers/infiniband/core/nldev.c:1849 rdma_nl_rcv_msg+0x392/0x6f0 drivers/infiniband/core/netlink.c:195 rdma_nl_rcv_skb.constprop.0.isra.0+0x2cb/0x410 drivers/infiniband/core/netlink.c:239 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline] netlink_unicast+0x585/0x850 net/netlink/af_netlink.c:1344 netlink_sendmsg+0x8b0/0xda0 net/netlink/af_netlink.c:1894 sock_sendmsg_nosec net/socket.c:787 [inline] __sock_sendmsg net/socket.c:802 [inline] ____sys_sendmsg+0x9e1/0xb70 net/socket.c:2698 ___sys_sendmsg+0x190/0x1e0 net/socket.c:2752 __sys_sendmsg+0x170/0x220 net/socket.c:2784 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x10b/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f727619ce59 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:00007f7276fc5028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 00007f7276416090 RCX: 00007f727619ce59 RDX: 0000000000000004 RSI: 0000200000004680 RDI: 0000000000000003 RBP: 00007f7276232d6f R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f7276416128 R14: 00007f7276416090 R15: 00007ffe765f7028 ---------------- Code disassembly (best guess): 0: cc int3 1: e8 70 f9 0e fd call 0xfd0ef976 6: 48 8d 3d 59 b9 e8 0b lea 0xbe8b959(%rip),%rdi # 0xbe8b966 d: 67 48 0f b9 3a ud1 (%edx),%rdi 12: e8 5f f9 0e fd call 0xfd0ef976 17: 5b pop %rbx 18: 5d pop %rbp 19: e9 d8 93 94 06 jmp 0x69493f6 1e: e8 53 f9 0e fd call 0xfd0ef976 23: 48 8d 3d 4c b9 e8 0b lea 0xbe8b94c(%rip),%rdi # 0xbe8b976 * 2a: 67 48 0f b9 3a ud1 (%edx),%rdi <-- trapping instruction 2f: e8 42 f9 0e fd call 0xfd0ef976 34: 5b pop %rbx 35: 5d pop %rbp 36: c3 ret 37: cc int3 38: cc int3 39: cc int3 3a: cc int3 3b: e8 36 f9 0e fd call 0xfd0ef976