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Commit 6cbf4c73 authored by OGAWA Hirofumi's avatar OGAWA Hirofumi Committed by Greg Kroah-Hartman
Browse files

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: default avatar <syzbot+ac94ae5f68b84197f41c@syzkaller.appspotmail.com>
Signed-off-by: default avatarOGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Reviewed-by: default avatarMing Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/875yqt1c9g.fsf@mail.parknet.co.jp


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 33a9ba52

block/bio.c

+2 −1
Original line number Diff line number Diff line
@@ -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;