Hello, I am hitting the following BUG while running syzkaller fuzzer:
kernel BUG at net/unix/garbage.c:149! invalid opcode: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN Dumping ftrace buffer: (ftrace buffer empty) Modules linked in: CPU: 0 PID: 23491 Comm: syz-executor Not tainted 4.9.0-rc5+ #41 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 task: ffff8801c16b06c0 task.stack: ffff8801c2928000 RIP: 0010:[<ffffffff8717ebf4>] [<ffffffff8717ebf4>] unix_notinflight+0x3b4/0x490 net/unix/garbage.c:149 RSP: 0018:ffff8801c292ea40 EFLAGS: 00010297 RAX: ffff8801c16b06c0 RBX: 1ffff10038525d4a RCX: dffffc0000000000 RDX: 0000000000000000 RSI: 1ffff10038525d4e RDI: ffffffff8a6e9d84 RBP: ffff8801c292eb18 R08: 0000000000000000 R09: 0000000000000000 R10: cdca594876e035a1 R11: 0000000000000005 R12: 1ffff10038525d4e R13: ffffffff899156e0 R14: ffff8801c292eaf0 R15: ffff88018b7cd780 FS: 00007f10420fa700(0000) GS:ffff8801d9800000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000002000a000 CR3: 00000001c2ecc000 CR4: 00000000001406f0 DR0: 0000000000000000 DR1: 0000000000000400 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600 Stack: dffffc0000000000 ffff88019f036970 0000000041b58ab3 ffffffff894c5120 ffffffff8717e840 ffff8801c16b06c0 ffff88018b7cdcf0 ffffffff894c51e2 ffffffff81576d50 0000000000000000 ffffffff00000000 1ffff10000000000 Call Trace: [<ffffffff8716cfbf>] unix_detach_fds.isra.19+0xff/0x170 net/unix/af_unix.c:1487 [<ffffffff8716f6a9>] unix_destruct_scm+0xf9/0x210 net/unix/af_unix.c:1496 [<ffffffff86a90a01>] skb_release_head_state+0x101/0x200 net/core/skbuff.c:655 [<ffffffff86a9808a>] skb_release_all+0x1a/0x60 net/core/skbuff.c:668 [<ffffffff86a980ea>] __kfree_skb+0x1a/0x30 net/core/skbuff.c:684 [<ffffffff86a98284>] kfree_skb+0x184/0x570 net/core/skbuff.c:705 [<ffffffff871789d5>] unix_release_sock+0x5b5/0xbd0 net/unix/af_unix.c:559 [<ffffffff87179039>] unix_release+0x49/0x90 net/unix/af_unix.c:836 [<ffffffff86a694b2>] sock_release+0x92/0x1f0 net/socket.c:570 [<ffffffff86a6962b>] sock_close+0x1b/0x20 net/socket.c:1017 [<ffffffff81a76b8e>] __fput+0x34e/0x910 fs/file_table.c:208 [<ffffffff81a771da>] ____fput+0x1a/0x20 fs/file_table.c:244 [<ffffffff81483ab0>] task_work_run+0x1a0/0x280 kernel/task_work.c:116 [< inline >] exit_task_work include/linux/task_work.h:21 [<ffffffff8141287a>] do_exit+0x183a/0x2640 kernel/exit.c:828 [<ffffffff8141383e>] do_group_exit+0x14e/0x420 kernel/exit.c:931 [<ffffffff814429d3>] get_signal+0x663/0x1880 kernel/signal.c:2307 [<ffffffff81239b45>] do_signal+0xc5/0x2190 arch/x86/kernel/signal.c:807 [<ffffffff8100666a>] exit_to_usermode_loop+0x1ea/0x2d0 arch/x86/entry/common.c:156 [< inline >] prepare_exit_to_usermode arch/x86/entry/common.c:190 [<ffffffff81009693>] syscall_return_slowpath+0x4d3/0x570 arch/x86/entry/common.c:259 [<ffffffff881478e6>] entry_SYSCALL_64_fastpath+0xc4/0xc6 Code: df 49 89 87 70 05 00 00 41 c6 04 14 f8 48 89 f9 48 c1 e9 03 80 3c 11 00 75 64 49 89 87 78 05 00 00 e9 65 ff ff ff e8 ac 94 56 fa <0f> 0b 48 89 d7 48 89 95 30 ff ff ff e8 bb 22 87 fa 48 8b 95 30 RIP [<ffffffff8717ebf4>] unix_notinflight+0x3b4/0x490 net/unix/garbage.c:149 RSP <ffff8801c292ea40> ---[ end trace 4cbbd52674b68dab ]--- On commit 16ae16c6e5616c084168740990fc508bda6655d4 (Nov 24). Unfortunately this is not reproducible outside of syzkaller. But easily reproducible with syzkaller. If you need to reproduce it, follow instructions described here: https://github.com/google/syzkaller/wiki/How-to-execute-syzkaller-programs With the following as the program: mmap(&(0x7f0000000000/0xdd5000)=nil, (0xdd5000), 0x3, 0x32, 0xffffffffffffffff, 0x0) socketpair$unix(0x1, 0x5, 0x0, &(0x7f0000dc7000-0x8)={<r0=>0x0, <r1=>0x0}) sendmmsg$unix(r1, &(0x7f0000dbf000-0xa8)=[{&(0x7f0000dbe000)=@file={0x1, ""}, 0x2, &(0x7f0000dbe000)=[], 0x0, &(0x7f0000dc4000)=[@rights={0x20, 0x1, 0x1, [r0, r0, r0, r1]}, @rights={0x14, 0x1, 0x1, [0xffffffffffffffff]}, @cred={0x20, 0x1, 0x2, 0x0, 0x0, 0x0}, @cred={0x20, 0x1, 0x2, 0x0, 0x0, 0x0}, @cred={0x20, 0x1, 0x2, 0x0, 0x0, 0x0}], 0x5, 0x800}, {&(0x7f0000dbf000-0x7d)=@file={0x1, ""}, 0x2, &(0x7f0000dbe000)=[], 0x0, &(0x7f0000dbf000-0x80)=[@rights={0x20, 0x1, 0x1, [0xffffffffffffffff, r1, 0xffffffffffffffff, r0]}, @cred={0x20, 0x1, 0x2, 0x0, 0x0, 0x0}, @cred={0x20, 0x1, 0x2, 0x0, 0x0, 0x0}, @cred={0x20, 0x1, 0x2, 0x0, 0x0, 0x0}], 0x4, 0x4}, {&(0x7f0000dbf000-0x8)=@abs={0x0, 0x0, 0x8}, 0x8, &(0x7f0000dbe000)=[{&(0x7f0000dc0000-0x27)="", 0x0}, {&(0x7f0000dc1000-0xb0)="", 0x0}, {&(0x7f0000dc2000-0xc4)="", 0x0}, {&(0x7f0000dc2000)="", 0x0}, {&(0x7f0000dc3000)="", 0x0}], 0x5, &(0x7f0000dbe000)=[@cred={0x20, 0x1, 0x2, 0x0, 0x0, 0x0}, @rights={0x14, 0x1, 0x1, [r1]}, @cred={0x20, 0x1, 0x2, 0x0, 0x0, 0x0}, @cred={0x20, 0x1, 0x2, 0x0, 0x0, 0x0}], 0x4, 0x4}], 0x3, 0x800) dup3(r1, r0, 0x80000) close(r1)
