general protection fault in relay_open_buf

syzbot
2019-01-30T18:53:57Z

Hello,

syzbot found the following crash on:

HEAD commit: 02495e76ded5 Add linux-next specific files for 20190130
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=12cf10df400000
kernel config: https://syzkaller.appspot.com/x/.config?x=a2b2e9c0bc43c14d
dashboard link: https://syzkaller.appspot.com/bug?extid=16c3a70e1e9b29346c43
compiler: gcc (GCC) 9.0.0 20181231 (experimental)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=13266698c00000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1715bb64c00000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+16c3a70e1e9b29346c43@syzkaller.appspotmail.com

kasan: CONFIG_KASAN_INLINE enabled
kasan: GPF could be caused by NULL-ptr deref or user memory access
general protection fault: 0000 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 8092 Comm: syz-executor405 Not tainted 5.0.0-rc4-next-20190130
#22
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
RIP: 0010:relay_set_buf_dentry kernel/relay.c:412 [inline]
RIP: 0010:relay_open_buf.part.0+0x7cb/0xb40 kernel/relay.c:458
Code: c1 ea 03 80 3c 02 00 0f 85 4c 03 00 00 49 8d 7d 58 4d 89 ac 24 90 00
00 00 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f
85 1b 03 00 00 48 b8 00 00 00 00 00 fc ff df 4d 8b
RSP: 0018:ffff888088897670 EFLAGS: 00010203
RAX: dffffc0000000000 RBX: ffff88809f2b3080 RCX: 1ffff110110c6919
RDX: 0000000000000008 RSI: ffffffff81833b80 RDI: 0000000000000047
RBP: ffff8880888976e8 R08: 0000000000000006 R09: ffff8880886348c8
R10: ffff888088634000 R11: 0000000000000000 R12: ffff88809f5ef580
R13: ffffffffffffffef R14: 0000000000000000 R15: 0000000000000000
FS: 00000000021c4880(0000) GS:ffff8880ae600000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000006cf090 CR3: 00000000a4ccd000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
relay_open_buf kernel/relay.c:447 [inline]
relay_open kernel/relay.c:597 [inline]
relay_open+0x5f3/0xaf0 kernel/relay.c:561
do_blk_trace_setup+0x50d/0xdb0 kernel/trace/blktrace.c:532
__blk_trace_setup+0xe3/0x190 kernel/trace/blktrace.c:577
blk_trace_ioctl+0x170/0x300 kernel/trace/blktrace.c:716
blkdev_ioctl+0x141/0x2120 block/ioctl.c:591
block_ioctl+0xee/0x130 fs/block_dev.c:1914
vfs_ioctl fs/ioctl.c:46 [inline]
file_ioctl fs/ioctl.c:509 [inline]
do_vfs_ioctl+0x107b/0x17d0 fs/ioctl.c:696
ksys_ioctl+0xab/0xd0 fs/ioctl.c:713
__do_sys_ioctl fs/ioctl.c:720 [inline]
__se_sys_ioctl fs/ioctl.c:718 [inline]
__x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:718
do_syscall_64+0x1a3/0x800 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x444af9
Code: e8 cc ab 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 db ce fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007ffd22903da8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000444af9
RDX: 0000000020000040 RSI: 00000000c0481273 RDI: 0000000000000003
RBP: 000000000000d8fa R08: 00000000021c4880 R09: 00000000004002e0
R10: 000000000000000f R11: 0000000000000246 R12: 0000000000401e60
R13: 0000000000401ef0 R14: 0000000000000000 R15: 0000000000000000
Modules linked in:
---[ end trace d79fd6b85e15805c ]---
RIP: 0010:relay_set_buf_dentry kernel/relay.c:412 [inline]
RIP: 0010:relay_open_buf.part.0+0x7cb/0xb40 kernel/relay.c:458
Code: c1 ea 03 80 3c 02 00 0f 85 4c 03 00 00 49 8d 7d 58 4d 89 ac 24 90 00
00 00 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f
85 1b 03 00 00 48 b8 00 00 00 00 00 fc ff df 4d 8b
RSP: 0018:ffff888088897670 EFLAGS: 00010203
RAX: dffffc0000000000 RBX: ffff88809f2b3080 RCX: 1ffff110110c6919
RDX: 0000000000000008 RSI: ffffffff81833b80 RDI: 0000000000000047
RBP: ffff8880888976e8 R08: 0000000000000006 R09: ffff8880886348c8
R10: ffff888088634000 R11: 0000000000000000 R12: ffff88809f5ef580
R13: ffffffffffffffef R14: 0000000000000000 R15: 0000000000000000
FS: 00000000021c4880(0000) GS:ffff8880ae600000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000006cf090 CR3: 00000000a4ccd000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400

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