Re: BUG: corrupted list in locks_delete_block

[Dmitry Vyukov <dvyukov@google.com>]

On Sun, Nov 11, 2018 at 10:18 AM, syzbot
<syzbot+13eb7470890c56ce3f37@syzkaller.appspotmail.com> wrote:
> Hello,
>
> syzbot found the following crash on:
>
> HEAD commit:    442b8cea2477 Add linux-next specific files for 20181109
> git tree:       linux-next
> console output: https://syzkaller.appspot.com/x/log.txt?x=12b1262b400000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=2f72bdb11df9fbe8
> dashboard link: https://syzkaller.appspot.com/bug?extid=13eb7470890c56ce3f37
> compiler:       gcc (GCC) 8.0.1 20180413 (experimental)
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=107566a3400000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=11b5fa2b400000
>
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+13eb7470890c56ce3f37@syzkaller.appspotmail.com

This is another manifestation of the following report, right?

#syz dup: KASAN: use-after-free Read in locks_delete_block

> list_del corruption. prev->next should be ffff8801c135f960, but was
> 0000000000000007
> ------------[ cut here ]------------
> kernel BUG at lib/list_debug.c:53!
> invalid opcode: 0000 [#1] PREEMPT SMP KASAN
> CPU: 1 PID: 5972 Comm: syz-executor001 Not tainted 4.20.0-rc1-next-20181109+
> #110
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
> Google 01/01/2011
> RIP: 0010:__list_del_entry_valid.cold.1+0x48/0x4a lib/list_debug.c:51
> Code: fe 60 88 e8 72 9b d3 fd 0f 0b 48 89 de 48 c7 c7 40 00 61 88 e8 61 9b
> d3 fd 0f 0b 48 89 de 48 c7 c7 e0 ff 60 88 e8 50 9b d3 fd <0f> 0b 48 89 d9 48
> c7 c7 a0 00 61 88 e8 3f 9b d3 fd 0f 0b 48 89 f1
> RSP: 0018:ffff8801c135f750 EFLAGS: 00010286
> RAX: 0000000000000054 RBX: ffff8801c135f960 RCX: 0000000000000000
> RDX: 0000000000000000 RSI: ffffffff8165ba15 RDI: 0000000000000005
> RBP: ffff8801c135f768 R08: ffff8801c11ce080 R09: ffffed003b5e5020
> R10: ffffed003b5e5020 R11: ffff8801daf28107 R12: ffff8801d945f3a0
> R13: ffff8801d945f3a0 R14: 0000000000000000 R15: ffff8801c135f838
> FS:  00007f96b449c700(0000) GS:ffff8801daf00000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 000000000046aa40 CR3: 00000001b39ab000 CR4: 00000000001406e0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> Call Trace:
>  __list_del_entry include/linux/list.h:117 [inline]
>  list_del_init include/linux/list.h:159 [inline]
>  __locks_delete_block fs/locks.c:683 [inline]
>  locks_delete_block+0xce/0x3d0 fs/locks.c:716
>  locks_mandatory_area+0x48b/0x6a0 fs/locks.c:1398
>  rw_verify_area+0x2f2/0x360 fs/read_write.c:386
>  do_iter_write+0x101/0x5f0 fs/read_write.c:954
>  vfs_writev+0x1f1/0x360 fs/read_write.c:1004
>  do_writev+0x11a/0x310 fs/read_write.c:1039
>  __do_sys_writev fs/read_write.c:1112 [inline]
>  __se_sys_writev fs/read_write.c:1109 [inline]
>  __x64_sys_writev+0x75/0xb0 fs/read_write.c:1109
>  do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
>  entry_SYSCALL_64_after_hwframe+0x49/0xbe
> RIP: 0033:0x446619
> Code: e8 6c b4 02 00 48 83 c4 18 c3 0f 1f 80 00 00 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
> 0f 83 2b 09 fc ff c3 66 2e 0f 1f 84 00 00 00 00
> RSP: 002b:00007f96b449bda8 EFLAGS: 00000297 ORIG_RAX: 0000000000000014
> RAX: ffffffffffffffda RBX: 00000000006dbc38 RCX: 0000000000446619
> RDX: 0000000000000001 RSI: 0000000020000440 RDI: 0000000000000003
> RBP: 00000000006dbc30 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000297 R12: 00000000006dbc3c
> R13: 2f30656c69662f2e R14: 64663d736e617274 R15: 00000000006dbd2c
> Modules linked in:
> ---[ end trace efdc3057b60b19f3 ]---
> RIP: 0010:__list_del_entry_valid.cold.1+0x48/0x4a lib/list_debug.c:51
> Code: fe 60 88 e8 72 9b d3 fd 0f 0b 48 89 de 48 c7 c7 40 00 61 88 e8 61 9b
> d3 fd 0f 0b 48 89 de 48 c7 c7 e0 ff 60 88 e8 50 9b d3 fd <0f> 0b 48 89 d9 48
> c7 c7 a0 00 61 88 e8 3f 9b d3 fd 0f 0b 48 89 f1
> RSP: 0018:ffff8801c135f750 EFLAGS: 00010286
> RAX: 0000000000000054 RBX: ffff8801c135f960 RCX: 0000000000000000
> RDX: 0000000000000000 RSI: ffffffff8165ba15 RDI: 0000000000000005
> RBP: ffff8801c135f768 R08: ffff8801c11ce080 R09: ffffed003b5e5020
> R10: ffffed003b5e5020 R11: ffff8801daf28107 R12: ffff8801d945f3a0
> R13: ffff8801d945f3a0 R14: 0000000000000000 R15: ffff8801c135f838
> FS:  00007f96b449c700(0000) GS:ffff8801daf00000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 000000000046aa40 CR3: 00000001b39ab000 CR4: 00000000001406e0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
>
>
> ---
> This bug is generated by a bot. It may contain errors.
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