From: OGAWA Hirofumi hirofumi@mail.parknet.co.jp
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 --- block/bio.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
--- a/block/bio.c +++ b/block/bio.c @@ -575,7 +575,8 @@ 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;