Re: [syzbot] [exfat?] KMSAN: uninit-value in vfat_rename2

[OGAWA Hirofumi]

Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> writes:

> On Fri, 04 Oct 2024 15:20:34 +0900 OGAWA Hirofumi <hirofumi@xxxxxxxxxxxxxxxxxx> wrote:
>
>> syzbot <syzbot+ef0d7bc412553291aa86@xxxxxxxxxxxxxxxxxxxxxxxxx> writes:
>> 
>> > git tree:       upstream
>> > console+strace: https://syzkaller.appspot.com/x/log.txt?x=11b54ea9980000
>> > kernel config:  https://syzkaller.appspot.com/x/.config?x=92da5062b0d65389
>> > dashboard link: https://syzkaller.appspot.com/bug?extid=ef0d7bc412553291aa86
>> > compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
>> > syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=14b7ed07980000
>> > C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=101dfd9f980000

[...]

>> > IMPORTANT: if you fix the issue, please add the following tag to the commit:
>> > Reported-by: syzbot+ef0d7bc412553291aa86@xxxxxxxxxxxxxxxxxxxxxxxxx
>> 
>> The patch fixes this bug. Please apply.
>> Thanks.
>> 
>> 
>> From: OGAWA Hirofumi <hirofumi@xxxxxxxxxxxxxxxxxx>
>> Subject: [PATCH] fat: Fix uninitialized variable
>> Date: Fri, 04 Oct 2024 15:03:49 +0900
>> 
>> Reported-by: syzbot+ef0d7bc412553291aa86@xxxxxxxxxxxxxxxxxxxxxxxxx
>> Signed-off-by: OGAWA Hirofumi <hirofumi@xxxxxxxxxxxxxxxxxx>
>
> Could we please have some description?  Seems that an IO error triggers this?

OK, I added the description guessed from syzbot log.

Thanks.


From: OGAWA Hirofumi <hirofumi@xxxxxxxxxxxxxxxxxx>
Subject: [PATCH v2] fat: Fix uninitialized variable
Date: Fri, 04 Oct 2024 15:03:49 +0900

This produced by corrupted fs image of syzbot, in theory, however IO
error would trigger this too.

This affects just a error report, so should not be serious error.

Reported-by: syzbot+ef0d7bc412553291aa86@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: OGAWA Hirofumi <hirofumi@xxxxxxxxxxxxxxxxxx>
---
 fs/fat/namei_vfat.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/fat/namei_vfat.c b/fs/fat/namei_vfat.c
index 6423e1d..15bf32c 100644
--- a/fs/fat/namei_vfat.c	2024-10-04 14:51:50.473038530 +0900
+++ b/fs/fat/namei_vfat.c	2024-10-04 14:56:53.108618655 +0900
@@ -1037,7 +1037,7 @@ error_inode:
 	if (corrupt < 0) {
 		fat_fs_error(new_dir->i_sb,
 			     "%s: Filesystem corrupted (i_pos %lld)",
-			     __func__, sinfo.i_pos);
+			     __func__, new_i_pos);
 	}
 	goto out;
 }
_
-- 
OGAWA Hirofumi <hirofumi@xxxxxxxxxxxxxxxxxx>