From: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
To: linux-block@vger.kernel.org
Cc: Jens Axboe <axboe@kernel.dk>,
glider@google.com, linux-kernel@vger.kernel.org,
syzkaller-bugs@googlegroups.com,
syzbot <syzbot+ac94ae5f68b84197f41c@syzkaller.appspotmail.com>
Subject: [PATCH] block: Fix wrong offset in bio_truncate()
Date: Sun, 09 Jan 2022 18:36:43 +0900 [thread overview]
Message-ID: <875yqt1c9g.fsf@mail.parknet.co.jp> (raw)
In-Reply-To: <000000000000880fca05d4fc73b0@google.com> (syzbot's message of "Fri, 07 Jan 2022 03:40:18 -0800")
bio_truncate() clears the buffer outside of last block of bdev, however
current bio_truncate() is using the wrong offset of page. So it can
return the uninitialized data.
This happened when both of truncated/corrupted FS and userspace (via
bdev) are trying to read the last of bdev.
Reported-by: syzbot+ac94ae5f68b84197f41c@syzkaller.appspotmail.com
Signed-off-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
---
block/bio.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/block/bio.c b/block/bio.c
index a6fb6a0..25f1ed2 100644
--- a/block/bio.c 2021-11-01 09:19:05.999472589 +0900
+++ b/block/bio.c 2022-01-09 17:40:09.010438012 +0900
@@ -567,7 +567,8 @@ void bio_truncate(struct bio *bio, unsig
offset = new_size - done;
else
offset = 0;
- zero_user(bv.bv_page, offset, bv.bv_len - offset);
+ zero_user(bv.bv_page, bv.bv_offset + offset,
+ bv.bv_len - offset);
truncated = true;
}
done += bv.bv_len;
_
--
OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
next prev parent reply other threads:[~2022-01-09 9:36 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-07 11:40 [syzbot] KMSAN: uninit-value in fat_subdirs syzbot
2022-01-09 9:36 ` OGAWA Hirofumi [this message]
2022-01-10 8:00 ` [PATCH] block: Fix wrong offset in bio_truncate() Ming Lei
2022-01-20 4:43 ` OGAWA Hirofumi
2022-01-20 13:30 ` Jens Axboe
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