From: Ming Lei <ming.lei@redhat.com>
To: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Cc: linux-block@vger.kernel.org, Jens Axboe <axboe@kernel.dk>,
glider@google.com, linux-kernel@vger.kernel.org,
syzkaller-bugs@googlegroups.com,
syzbot <syzbot+ac94ae5f68b84197f41c@syzkaller.appspotmail.com>
Subject: Re: [PATCH] block: Fix wrong offset in bio_truncate()
Date: Mon, 10 Jan 2022 16:00:00 +0800 [thread overview]
Message-ID: <YdvngICmbNXOFIIj@T590> (raw)
In-Reply-To: <875yqt1c9g.fsf@mail.parknet.co.jp>
On Sun, Jan 09, 2022 at 06:36:43PM +0900, OGAWA Hirofumi wrote:
> 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);
Looks correct:
Reviewed-by: Ming Lei <ming.lei@redhat.com>
--
Ming
next prev parent reply other threads:[~2022-01-10 8:02 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 ` [PATCH] block: Fix wrong offset in bio_truncate() OGAWA Hirofumi
2022-01-10 8:00 ` Ming Lei [this message]
2022-01-20 4:43 ` OGAWA Hirofumi
2022-01-20 13:30 ` Jens Axboe
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