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* general protection fault in ext4_commit_super
@ 2020-12-22  8:54 syzbot
       [not found] ` <20201222100908.1782-1-hdanton@sina.com>
  0 siblings, 1 reply; 3+ messages in thread
From: syzbot @ 2020-12-22  8:54 UTC (permalink / raw)
  To: adilger.kernel, clang-built-linux, jack, linux-ext4,
	linux-kernel, natechancellor, ndesaulniers, syzkaller-bugs,
	tytso

Hello,

syzbot found the following issue on:

HEAD commit:    0d52778b Add linux-next specific files for 20201218
git tree:       linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=15b4aecb500000
kernel config:  https://syzkaller.appspot.com/x/.config?x=5c81cc44aa25b5b3
dashboard link: https://syzkaller.appspot.com/bug?extid=9043030c040ce1849a60
compiler:       gcc (GCC) 10.1.0-syz 20200507
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=17983487500000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=10c02937500000

The issue was bisected to:

commit e810c942a325cf749e859d7aa3a43dc219cea299
Author: Jan Kara <jack@suse.cz>
Date:   Wed Dec 16 10:18:40 2020 +0000

    ext4: save error info to sb through journal if available

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=1282f137500000
final oops:     https://syzkaller.appspot.com/x/report.txt?x=1182f137500000
console output: https://syzkaller.appspot.com/x/log.txt?x=1682f137500000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+9043030c040ce1849a60@syzkaller.appspotmail.com
Fixes: e810c942a325 ("ext4: save error info to sb through journal if available")

general protection fault, probably for non-canonical address 0xdffffc000000000c: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000060-0x0000000000000067]
CPU: 0 PID: 7 Comm: kworker/0:1 Not tainted 5.10.0-next-20201218-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events flush_stashed_error_work
RIP: 0010:ext4_commit_super+0x52/0x510 fs/ext4/super.c:5548
Code: 48 c1 ea 03 80 3c 02 00 0f 85 21 04 00 00 48 8b 9d 78 06 00 00 48 b8 00 00 00 00 00 fc ff df 48 8d 7b 60 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 f1 03 00 00 48 8b 5b 60 48 85 db 0f 84 13 01 00
RSP: 0018:ffffc90000cc7cb8 EFLAGS: 00010206
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 000000000000000c RSI: ffffffff8217a0db RDI: 0000000000000060
RBP: ffff88802441c000 R08: 0000000000000000 R09: 0000000000000000
R10: ffffffff8217a7fa R11: 0000000000000000 R12: ffff88802441c000
R13: ffff88802441c678 R14: ffff8880109a5a00 R15: ffff8880b9c34440
FS:  0000000000000000(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000400200 CR3: 0000000014038000 CR4: 00000000001506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 flush_stashed_error_work+0x1c9/0x2a0 fs/ext4/super.c:727
 process_one_work+0x98d/0x1630 kernel/workqueue.c:2275
 worker_thread+0x64c/0x1120 kernel/workqueue.c:2421
 kthread+0x3b1/0x4a0 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296
Modules linked in:
---[ end trace dca7dc492b64f0a6 ]---
RIP: 0010:ext4_commit_super+0x52/0x510 fs/ext4/super.c:5548
Code: 48 c1 ea 03 80 3c 02 00 0f 85 21 04 00 00 48 8b 9d 78 06 00 00 48 b8 00 00 00 00 00 fc ff df 48 8d 7b 60 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 f1 03 00 00 48 8b 5b 60 48 85 db 0f 84 13 01 00
RSP: 0018:ffffc90000cc7cb8 EFLAGS: 00010206
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 000000000000000c RSI: ffffffff8217a0db RDI: 0000000000000060
RBP: ffff88802441c000 R08: 0000000000000000 R09: 0000000000000000
R10: ffffffff8217a7fa R11: 0000000000000000 R12: ffff88802441c000
R13: ffff88802441c678 R14: ffff8880109a5a00 R15: ffff8880b9c34440
FS:  0000000000000000(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000400200 CR3: 0000000025563000 CR4: 00000000001506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
For information about bisection process see: https://goo.gl/tpsmEJ#bisection
syzbot can test patches for this issue, for details see:
https://goo.gl/tpsmEJ#testing-patches

^ permalink raw reply	[flat|nested] 3+ messages in thread
* Re: general protection fault in ext4_commit_super
       [not found] ` <20201222100908.1782-1-hdanton@sina.com>
@ 2020-12-22 11:28   ` Jan Kara
  2020-12-22 18:13     ` Theodore Y. Ts'o
  0 siblings, 1 reply; 3+ messages in thread
From: Jan Kara @ 2020-12-22 11:28 UTC (permalink / raw)
  To: Hillf Danton
  Cc: syzbot, jack, linux-ext4, linux-kernel, syzkaller-bugs, tytso

[-- Attachment #1: Type: text/plain, Size: 3776 bytes --]

On Tue 22-12-20 18:09:08, Hillf Danton wrote:
> Tue, 22 Dec 2020 00:54:15 -0800
> > syzbot found the following issue on:
> > 
> > HEAD commit:    0d52778b Add linux-next specific files for 20201218
> > git tree:       linux-next
> > console output: https://syzkaller.appspot.com/x/log.txt?x=15b4aecb500000
> > kernel config:  https://syzkaller.appspot.com/x/.config?x=5c81cc44aa25b5b3
> > dashboard link: https://syzkaller.appspot.com/bug?extid=9043030c040ce1849a60
> > compiler:       gcc (GCC) 10.1.0-syz 20200507
> > syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=17983487500000
> > C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=10c02937500000
> > 
> > The issue was bisected to:
> > 
> > commit e810c942a325cf749e859d7aa3a43dc219cea299
> > Author: Jan Kara <jack@suse.cz>
> > Date:   Wed Dec 16 10:18:40 2020 +0000
> > 
> >     ext4: save error info to sb through journal if available
> > 
> > bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=1282f137500000
> > final oops:     https://syzkaller.appspot.com/x/report.txt?x=1182f137500000
> > console output: https://syzkaller.appspot.com/x/log.txt?x=1682f137500000
> > 
> > IMPORTANT: if you fix the issue, please add the following tag to the commit:
> > Reported-by: syzbot+9043030c040ce1849a60@syzkaller.appspotmail.com
> > Fixes: e810c942a325 ("ext4: save error info to sb through journal if available")
> > 
> > general protection fault, probably for non-canonical address 0xdffffc000000000c: 0000 [#1] PREEMPT SMP KASAN
> > KASAN: null-ptr-deref in range [0x0000000000000060-0x0000000000000067]
> > CPU: 0 PID: 7 Comm: kworker/0:1 Not tainted 5.10.0-next-20201218-syzkaller #0
> > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> > Workqueue: events flush_stashed_error_work
> > RIP: 0010:ext4_commit_super+0x52/0x510 fs/ext4/super.c:5548
> > Code: 48 c1 ea 03 80 3c 02 00 0f 85 21 04 00 00 48 8b 9d 78 06 00 00 48 b8 00 00 00 00 00 fc ff df 48 8d 7b 60 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 f1 03 00 00 48 8b 5b 60 48 85 db 0f 84 13 01 00
> > RSP: 0018:ffffc90000cc7cb8 EFLAGS: 00010206
> > RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000000
> > RDX: 000000000000000c RSI: ffffffff8217a0db RDI: 0000000000000060
> > RBP: ffff88802441c000 R08: 0000000000000000 R09: 0000000000000000
> > R10: ffffffff8217a7fa R11: 0000000000000000 R12: ffff88802441c000
> > R13: ffff88802441c678 R14: ffff8880109a5a00 R15: ffff8880b9c34440
> > FS:  0000000000000000(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000
> > CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> > CR2: 0000000000400200 CR3: 0000000014038000 CR4: 00000000001506f0
> > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> > Call Trace:
> >  flush_stashed_error_work+0x1c9/0x2a0 fs/ext4/super.c:727
> >  process_one_work+0x98d/0x1630 kernel/workqueue.c:2275
> >  worker_thread+0x64c/0x1120 kernel/workqueue.c:2421
> >  kthread+0x3b1/0x4a0 kernel/kthread.c:292
> >  ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296
> 
> Fix e810c942a325 ("ext4: save error info to sb through journal if available")
> by flushing work as part of rollback.

Thanks for having a look. I don't think the fix is quite correct though. The
flush_work() should be at failed_mount3: label. So something like attached
fixup. Ted, can you please fold it into the buggy commit?

								Honza

> --- a/fs/ext4/super.c
> +++ b/fs/ext4/super.c
> @@ -5171,6 +5171,7 @@ out_fail:
>  	sb->s_fs_info = NULL;
>  	kfree(sbi->s_blockgroup_lock);
>  out_free_base:
> +	flush_work(&sbi->s_error_work);
>  	kfree(sbi);
>  	kfree(orig_data);
>  	fs_put_dax(dax_dev);
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR

[-- Attachment #2: 0001-Fixup-error-handling-on-sb-load.patch --]
[-- Type: text/x-patch, Size: 790 bytes --]

From b3f87141c5944d4dba8e462e1c9ce0c723434fbb Mon Sep 17 00:00:00 2001
From: Jan Kara <jack@suse.cz>
Date: Tue, 22 Dec 2020 12:26:26 +0100
Subject: [PATCH] Fixup error handling on sb load

Reported-by: syzbot+9043030c040ce1849a60@syzkaller.appspotmail.com
Signed-off-by: Jan Kara <jack@suse.cz>
---
 fs/ext4/super.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 502ae491d07d..c2311978f9b0 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -5142,6 +5142,7 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
 	ext4_es_unregister_shrinker(sbi);
 failed_mount3:
 	del_timer_sync(&sbi->s_err_report);
+	flush_work(&sbi->s_error_work);
 	if (sbi->s_mmp_tsk)
 		kthread_stop(sbi->s_mmp_tsk);
 failed_mount2:
-- 
2.16.4


^ permalink raw reply related	[flat|nested] 3+ messages in thread
* Re: general protection fault in ext4_commit_super
  2020-12-22 11:28   ` Jan Kara
@ 2020-12-22 18:13     ` Theodore Y. Ts'o
  0 siblings, 0 replies; 3+ messages in thread
From: Theodore Y. Ts'o @ 2020-12-22 18:13 UTC (permalink / raw)
  To: Jan Kara; +Cc: Hillf Danton, syzbot, linux-ext4, linux-kernel, syzkaller-bugs

On Tue, Dec 22, 2020 at 12:28:53PM +0100, Jan Kara wrote:
> > Fix e810c942a325 ("ext4: save error info to sb through journal if available")
> > by flushing work as part of rollback.
> 
> Thanks for having a look. I don't think the fix is quite correct though. The
> flush_work() should be at failed_mount3: label. So something like attached
> fixup. Ted, can you please fold it into the buggy commit?

Done.  I folded it into "ext4: defer saving error info from atomic
context" since this is the commit where we introduced the s_error_work
workqueue.

Thanks!!

						- Ted

^ permalink raw reply	[flat|nested] 3+ messages in thread
end of thread, other threads:[~2020-12-22 18:14 UTC | newest]

Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-12-22  8:54 general protection fault in ext4_commit_super syzbot
     [not found] ` <20201222100908.1782-1-hdanton@sina.com>
2020-12-22 11:28   ` Jan Kara
2020-12-22 18:13     ` Theodore Y. Ts'o

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