------------[ cut here ]------------ refcount_t: underflow; use-after-free. WARNING: lib/refcount.c:28 at refcount_warn_saturate+0xf4/0x130 lib/refcount.c:28, CPU#1: syz.8.4131/20639 Modules linked in: CPU: 1 UID: 0 PID: 20639 Comm: syz.8.4131 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 60 a7 0f fd 48 8d 3d 99 d0 ec 0b 67 48 0f b9 3a e8 4f a7 0f fd 5b 5d e9 48 27 a4 06 e8 43 a7 0f fd 48 8d 3d 8c d0 ec 0b <67> 48 0f b9 3a e8 32 a7 0f fd 5b 5d c3 cc cc cc cc e8 26 a7 0f fd RSP: 0018:ffffc90003aaf120 EFLAGS: 00010293 RAX: 0000000000000000 RBX: ffff8880368a2280 RCX: ffffffff84f9d30b RDX: ffff888061e04a00 RSI: ffffffff84f9d39d RDI: ffffffff90e6a430 RBP: 0000000000000003 R08: 0000000000000005 R09: 0000000000000004 R10: 0000000000000003 R11: 0000000000000000 R12: ffff8880368a2280 R13: ffffffff8a0c6f20 R14: 0000000000000000 R15: 0000000000000018 FS: 00007fd377c686c0(0000) GS:ffff8880d63db000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000001b33023ffc CR3: 00000000308a1000 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: 0033:0x7fd376d9c819 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:00007fd377c68028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 00007fd377016090 RCX: 00007fd376d9c819 RDX: 0000000000000004 RSI: 0000200000004680 RDI: 0000000000000003 RBP: 00007fd376e32c91 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fd377016128 R14: 00007fd377016090 R15: 00007ffe66f5e6c8 ---------------- Code disassembly (best guess): 0: cc int3 1: e8 60 a7 0f fd call 0xfd0fa766 6: 48 8d 3d 99 d0 ec 0b lea 0xbecd099(%rip),%rdi # 0xbecd0a6 d: 67 48 0f b9 3a ud1 (%edx),%rdi 12: e8 4f a7 0f fd call 0xfd0fa766 17: 5b pop %rbx 18: 5d pop %rbp 19: e9 48 27 a4 06 jmp 0x6a42766 1e: e8 43 a7 0f fd call 0xfd0fa766 23: 48 8d 3d 8c d0 ec 0b lea 0xbecd08c(%rip),%rdi # 0xbecd0b6 * 2a: 67 48 0f b9 3a ud1 (%edx),%rdi <-- trapping instruction 2f: e8 32 a7 0f fd call 0xfd0fa766 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 26 a7 0f fd call 0xfd0fa766