general protection fault in relay_open

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: 089cf7f6 Linux 5.3-rc7
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=160c292a600000
kernel config: https://syzkaller.appspot.com/x/.config?x=144488c6c6c6d2b6
dashboard link: https://syzkaller.appspot.com/bug?extid=d6074fb08bdb2e010520
compiler: clang version 9.0.0 (/home/glider/llvm/clang
80fee25776c2fb61e74c1ecb1a523375c2500b69)
CC: [gre...@linuxfoundation.org ja...@google.com
linux-...@vger.kernel.org vi...@zeniv.linux.org.uk]

Unfortunately, I don't have any reproducer for this crash yet.

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+d6074f...@syzkaller.appspotmail.com

debugfs: File 'trace0' in directory 'sg0' already present!
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: 30987 Comm: syz-executor.5 Not tainted 5.3.0-rc7 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
RIP: 0010:relay_close_buf kernel/relay.c:495 [inline]
RIP: 0010:relay_open+0x65a/0x970 kernel/relay.c:612
Code: ff df 80 3c 08 00 74 08 48 89 df e8 f0 3d 38 00 4c 8b 3b 4d 85 ff 0f
84 f4 00 00 00 49 8d bf ac 00 00 00 48 89 f8 48 c1 e8 03 <42> 0f b6 04 20
84 c0 0f 85 50 01 00 00 41 c7 87 ac 00 00 00 01 00
RSP: 0018:ffff88803610fbd8 EFLAGS: 00010207
RAX: 0000000020000014 RBX: ffff8880aeb00000 RCX: dffffc0000000000
RDX: ffffc9001119e000 RSI: 000000000001c2d1 RDI: 00000001000000a4
RBP: ffff88803610fc40 R08: ffffffff83516ace R09: ffffed1006c21f51
R10: ffffed1006c21f51 R11: 0000000000000000 R12: dffffc0000000000
R13: 1ffffffff117bec9 R14: 0000000000000001 R15: 00000000fffffff8
FS: 00007f099074c700(0000) GS:ffff8880aea00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000738000 CR3: 000000009ba15000 CR4: 00000000001426f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
do_blk_trace_setup+0x4b9/0xaa0 kernel/trace/blktrace.c:526
__blk_trace_setup kernel/trace/blktrace.c:571 [inline]
blk_trace_setup+0x8d/0x110 kernel/trace/blktrace.c:589
sg_ioctl+0xd82/0x2c60 drivers/scsi/sg.c:1112
do_vfs_ioctl+0x744/0x1730 fs/ioctl.c:46
ksys_ioctl fs/ioctl.c:713 [inline]
__do_sys_ioctl fs/ioctl.c:720 [inline]
__se_sys_ioctl fs/ioctl.c:718 [inline]
__x64_sys_ioctl+0xe3/0x120 fs/ioctl.c:718
do_syscall_64+0xfe/0x140 arch/x86/entry/common.c:296
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x459879
Code: fd b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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 cb b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f099074bc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000459879
RDX: 0000000020000100 RSI: 00000000c0481273 RDI: 0000000000000003
RBP: 000000000075bfc8 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f099074c6d4
R13: 00000000004c0f39 R14: 00000000004d4150 R15: 00000000ffffffff
Modules linked in:
---[ end trace 85383590ad216193 ]---
RIP: 0010:relay_close_buf kernel/relay.c:495 [inline]
RIP: 0010:relay_open+0x65a/0x970 kernel/relay.c:612
Code: ff df 80 3c 08 00 74 08 48 89 df e8 f0 3d 38 00 4c 8b 3b 4d 85 ff 0f
84 f4 00 00 00 49 8d bf ac 00 00 00 48 89 f8 48 c1 e8 03 <42> 0f b6 04 20
84 c0 0f 85 50 01 00 00 41 c7 87 ac 00 00 00 01 00
RSP: 0018:ffff88803610fbd8 EFLAGS: 00010207
RAX: 0000000020000014 RBX: ffff8880aeb00000 RCX: dffffc0000000000
RDX: ffffc9001119e000 RSI: 000000000001c2d1 RDI: 00000001000000a4
RBP: ffff88803610fc40 R08: ffffffff83516ace R09: ffffed1006c21f51
R10: ffffed1006c21f51 R11: 0000000000000000 R12: dffffc0000000000
R13: 1ffffffff117bec9 R14: 0000000000000001 R15: 00000000fffffff8
FS: 00007f099074c700(0000) GS:ffff8880aea00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fa50a28e518 CR3: 000000009ba15000 CR4: 00000000001426f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.