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@xxxxxxx> > > 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@xxxxxxxxxxxxxxxxxxxxxxxxx > > 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@xxxxxxxx> SUSE Labs, CR
>From b3f87141c5944d4dba8e462e1c9ce0c723434fbb Mon Sep 17 00:00:00 2001 From: Jan Kara <jack@xxxxxxx> Date: Tue, 22 Dec 2020 12:26:26 +0100 Subject: [PATCH] Fixup error handling on sb load Reported-by: syzbot+9043030c040ce1849a60@xxxxxxxxxxxxxxxxxxxxxxxxx Signed-off-by: Jan Kara <jack@xxxxxxx> --- 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
