block: Fix wrong offset in bio_truncate()

mainline inclusion
from mainline-v5.17-rc1
commit 3ee859e3
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I6GTUI
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=3ee859e384d453d6ac68bfd5971f630d9fa46ad3

--------------------------------

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: NOGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Reviewed-by: NMing Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/875yqt1c9g.fsf@mail.parknet.co.jpSigned-off-by: NJens Axboe <axboe@kernel.dk>
Signed-off-by: NYu Kuai <yukuai3@huawei.com>
Reviewed-by: NHou Tao <houtao1@huawei.com>
Signed-off-by: NYongqiang Liu <liuyongqiang13@huawei.com>

block/bio.c

@@ -578,7 +578,8 @@ 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;