general protection fault in __fget

general protection fault in __fget_files
Status: upstream: reported syz repro on 2020/11/03 17:43
Reported-by: syzbot+4bbd040ddada1c7801f4@syzkaller.appspotmail.com
First crash: 30d, last: 30d

Cause bisection: introduced by (bisect log) :
commit 4d004099a668c41522242aa146a38cc4eb59cb1e
Author: Peter Zijlstra <peterz@infradead.org>
Date: Fri Oct 2 09:04:21 2020 +0000

lockdep: Fix lockdep recursion

Crash: BUG: using __this_cpu_read() in preemptible code in trace_hardirqs_on (log)
Repro: syz .config

Sample crash report:

general protection fault, probably for non-canonical address 0xdffffc000000000b: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000058-0x000000000000005f]
CPU: 1 PID: 8824 Comm: io_uring-sq Not tainted 5.10.0-rc1-next-20201102-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:fcheck_files include/linux/fdtable.h:99 [inline]
RIP: 0010:__fget_files+0xef/0x400 fs/file.c:829
Code: db 74 1d e8 43 0d ac ff 0f b6 1d c1 82 14 0b 31 ff 89 de e8 43 05 ac ff 84 db 0f 84 d0 01 00 00 e8 26 0d ac ff 48 8b 44 24 10 <80> 38 00 0f 85 c3 02 00 00 48 8b 44 24 08 48 8b 68 58 48 89 e8 48
RSP: 0018:ffffc900023dfb28 EFLAGS: 00010293
RAX: dffffc000000000b RBX: 0000000000000001 RCX: ffffffff81c4157a
RDX: ffff88814193b500 RSI: ffffffff81c4139a RDI: 0000000000000005
RBP: ffffc900023dfd20 R08: 0000000000000001 R09: ffffffff8ebb4667
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: dffffc0000000000 R14: 0000000000000003 R15: ffffc900023dfd30
FS:  0000000000000000(0000) GS:ffff8880b9f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f42329d7db8 CR3: 000000001b67b000 CR4: 00000000001506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 __io_file_get fs/io_uring.c:2770 [inline]
 io_file_get+0x454/0x8b0 fs/io_uring.c:6295
 io_req_set_file fs/io_uring.c:6304 [inline]
 io_init_req fs/io_uring.c:6724 [inline]
 io_submit_sqes+0xf1c/0x25f0 fs/io_uring.c:6774
 __io_sq_thread fs/io_uring.c:6921 [inline]
 io_sq_thread+0x4d2/0x1700 fs/io_uring.c:6990
 kthread+0x3af/0x4a0 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296
Modules linked in:
---[ end trace 71851a1d0e522d2e ]---
RIP: 0010:fcheck_files include/linux/fdtable.h:99 [inline]
RIP: 0010:__fget_files+0xef/0x400 fs/file.c:829
Code: db 74 1d e8 43 0d ac ff 0f b6 1d c1 82 14 0b 31 ff 89 de e8 43 05 ac ff 84 db 0f 84 d0 01 00 00 e8 26 0d ac ff 48 8b 44 24 10 <80> 38 00 0f 85 c3 02 00 00 48 8b 44 24 08 48 8b 68 58 48 89 e8 48
RSP: 0018:ffffc900023dfb28 EFLAGS: 00010293
RAX: dffffc000000000b RBX: 0000000000000001 RCX: ffffffff81c4157a
RDX: ffff88814193b500 RSI: ffffffff81c4139a RDI: 0000000000000005
RBP: ffffc900023dfd20 R08: 0000000000000001 R09: ffffffff8ebb4667
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: dffffc0000000000 R14: 0000000000000003 R15: ffffc900023dfd30
FS:  0000000000000000(0000) GS:ffff8880b9e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffdc225dc7c CR3: 000000000b08e000 CR4: 00000000001506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400

Crashes (2):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	Syz repro	C repro	VM info	Maintainers
ci-upstream-linux-next-kasan-gce-root	2020/11/02 23:46	linux-next	b49976d8	8bc4594f	.config	log	report	syz			linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk
ci-upstream-linux-next-kasan-gce-root	2020/11/02 23:26	linux-next	b49976d8	8bc4594f	.config	log	report			info	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk