Messages in this thread Patch in this message | | | From | OGAWA Hirofumi <> | Subject | [PATCH] block: Fix wrong offset in bio_truncate() | Date | Sun, 09 Jan 2022 18:36:43 +0900 |
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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> --- block/bio.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/block/bio.c b/block/bio.c index a6fb6a0..25f1ed2 100644 --- a/block/bio.c 2021-11-01 09:19:05.999472589 +0900 +++ b/block/bio.c 2022-01-09 17:40:09.010438012 +0900 @@ -567,7 +567,8 @@ 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; _ -- OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
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