From: OGAWA Hirofumi <hirofumi@xxxxxxxxxxxxxxxxxx> 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@xxxxxxxxxxxxxxxxxxxxxxxxx Signed-off-by: OGAWA Hirofumi <hirofumi@xxxxxxxxxxxxxxxxxx> Reviewed-by: Ming Lei <ming.lei@xxxxxxxxxx> Link: https://lore.kernel.org/r/875yqt1c9g.fsf@xxxxxxxxxxxxxxxxxx Signed-off-by: Jens Axboe <axboe@xxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- block/bio.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- a/block/bio.c +++ b/block/bio.c @@ -569,7 +569,8 @@ 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;
