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Date:   Tue, 29 Nov 2022 09:08:33 -0800
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Subject: Re: [syzbot] WARNING in rmqueue
From:   syzbot <syzbot+aafb3f37cfeb6534c4ac@syzkaller.appspotmail.com>
To:     hdanton@sina.com, linux-kernel@vger.kernel.org,
        syzkaller-bugs@googlegroups.com
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Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
BUG: unable to handle kernel paging request in z_erofs_decompress_queue

BUG: unable to handle page fault for address: fffff5210193fffa
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 23ffed067 P4D 23ffed067 PUD 0 
Oops: 0000 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 48 Comm: kworker/u5:0 Not tainted 6.1.0-rc7-syzkaller-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022
Workqueue: erofs_unzipd z_erofs_decompressqueue_work
RIP: 0010:z_erofs_do_decompressed_bvec fs/erofs/zdata.c:896 [inline]
RIP: 0010:z_erofs_parse_out_bvecs fs/erofs/zdata.c:969 [inline]
RIP: 0010:z_erofs_decompress_pcluster fs/erofs/zdata.c:1056 [inline]
RIP: 0010:z_erofs_decompress_queue+0xad1/0x2c30 fs/erofs/zdata.c:1155
Code: a8 00 00 00 42 80 3c 20 00 74 0a 48 8b 7c 24 70 e8 d4 1c f6 fd 89 db 48 c1 e3 03 48 03 9c 24 40 03 00 00 49 89 de 49 c1 ee 03 <43> 80 3c 26 00 74 08 48 89 df e8 b0 1c f6 fd 48 83 3b 00 0f 84 bd
RSP: 0018:ffffc90000b97780 EFLAGS: 00010a06
RAX: 1ffff92000172f58 RBX: ffffc9080c9fffd0 RCX: 0000000000000000
RDX: ffff888018b2d7c0 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc90000b97b90 R08: ffffffff83e894a8 R09: fffff52001940000
R10: fffffbfff23bc68d R11: 1ffffffff23bc68c R12: dffffc0000000000
R13: 00000000ffff9f00 R14: 1ffff9210193fffa R15: ffff8880717b71f0
FS:  0000000000000000(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: fffff5210193fffa CR3: 00000000277fc000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 z_erofs_decompressqueue_work+0x95/0xe0 fs/erofs/zdata.c:1167
 process_one_work+0x877/0xdb0 kernel/workqueue.c:2289
 worker_thread+0xb14/0x1330 kernel/workqueue.c:2436
 kthread+0x266/0x300 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306
 </TASK>
Modules linked in:
CR2: fffff5210193fffa
---[ end trace 0000000000000000 ]---
RIP: 0010:z_erofs_do_decompressed_bvec fs/erofs/zdata.c:896 [inline]
RIP: 0010:z_erofs_parse_out_bvecs fs/erofs/zdata.c:969 [inline]
RIP: 0010:z_erofs_decompress_pcluster fs/erofs/zdata.c:1056 [inline]
RIP: 0010:z_erofs_decompress_queue+0xad1/0x2c30 fs/erofs/zdata.c:1155
Code: a8 00 00 00 42 80 3c 20 00 74 0a 48 8b 7c 24 70 e8 d4 1c f6 fd 89 db 48 c1 e3 03 48 03 9c 24 40 03 00 00 49 89 de 49 c1 ee 03 <43> 80 3c 26 00 74 08 48 89 df e8 b0 1c f6 fd 48 83 3b 00 0f 84 bd
RSP: 0018:ffffc90000b97780 EFLAGS: 00010a06
RAX: 1ffff92000172f58 RBX: ffffc9080c9fffd0 RCX: 0000000000000000
RDX: ffff888018b2d7c0 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc90000b97b90 R08: ffffffff83e894a8 R09: fffff52001940000
R10: fffffbfff23bc68d R11: 1ffffffff23bc68c R12: dffffc0000000000
R13: 00000000ffff9f00 R14: 1ffff9210193fffa R15: ffff8880717b71f0
FS:  0000000000000000(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: fffff5210193fffa CR3: 00000000277fc000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
   0:	a8 00                	test   $0x0,%al
   2:	00 00                	add    %al,(%rax)
   4:	42 80 3c 20 00       	cmpb   $0x0,(%rax,%r12,1)
   9:	74 0a                	je     0x15
   b:	48 8b 7c 24 70       	mov    0x70(%rsp),%rdi
  10:	e8 d4 1c f6 fd       	callq  0xfdf61ce9
  15:	89 db                	mov    %ebx,%ebx
  17:	48 c1 e3 03          	shl    $0x3,%rbx
  1b:	48 03 9c 24 40 03 00 	add    0x340(%rsp),%rbx
  22:	00
  23:	49 89 de             	mov    %rbx,%r14
  26:	49 c1 ee 03          	shr    $0x3,%r14
* 2a:	43 80 3c 26 00       	cmpb   $0x0,(%r14,%r12,1) <-- trapping instruction
  2f:	74 08                	je     0x39
  31:	48 89 df             	mov    %rbx,%rdi
  34:	e8 b0 1c f6 fd       	callq  0xfdf61ce9
  39:	48 83 3b 00          	cmpq   $0x0,(%rbx)
  3d:	0f                   	.byte 0xf
  3e:	84                   	.byte 0x84
  3f:	bd                   	.byte 0xbd


Tested on:

commit:         b7b275e6 Linux 6.1-rc7
git tree:       https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
console output: https://syzkaller.appspot.com/x/log.txt?x=15bd42a7880000
kernel config:  https://syzkaller.appspot.com/x/.config?x=2325e409a9a893e1
dashboard link: https://syzkaller.appspot.com/bug?extid=aafb3f37cfeb6534c4ac
compiler:       Debian clang version 13.0.1-++20220126092033+75e33f71c2da-1~exp1~20220126212112.63, GNU ld (GNU Binutils for Debian) 2.35.2
patch:          https://syzkaller.appspot.com/x/patch.diff?x=11028fed880000