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block: Fix wrong offset in bio_truncate() 

commit 3ee859e384d453d6ac68bfd5971f630d9fa46ad3 upstream.

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>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/875yqt1c9g.fsf@mail.parknet.co.jp
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
OGAWA Hirofumi 2022-01-09 18:36:43 +09:00 committed by Greg Kroah-Hartman
parent 33a9ba52d5
commit 6cbf4c731d
1 changed files with 2 additions and 1 deletions
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3
block/bio.c
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@ -569,7 +569,8 @@ void bio_truncate(struct bio *bio, unsigned new_size)
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;