From 3ee859e384d453d6ac68bfd5971f630d9fa46ad3 Mon Sep 17 00:00:00 2001
From: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Date: Sun, 9 Jan 2022 18:36:43 +0900
Subject: [PATCH] block: Fix wrong offset in bio_truncate()
Git-commit: 3ee859e384d453d6ac68bfd5971f630d9fa46ad3
Patch-mainline: v5.17-rc1
References: bsc#1202780
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>
Acked-by: Jan Kara <jack@suse.cz>
---
block/bio.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/block/bio.c b/block/bio.c
index 0d400ba2dbd1..4312a8085396 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -569,7 +569,8 @@ static 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;
--
2.35.3