From: Jan Kara <jack@suse.com>
Date: Wed, 4 Nov 2015 16:13:39 +0000 (+0100)
Subject: brd: Refuse improperly aligned discard requests
X-Git-Tag: firefly_0821_release~176^2~701^2~9
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=2dbe5495763612f7c1b68fc897cd28c9e22079b8;p=firefly-linux-kernel-4.4.55.git

brd: Refuse improperly aligned discard requests

Currently when improperly aligned discard request is submitted, we just
silently discard more / less data which results in filesystem corruption
in some cases. Refuse such misaligned requests.

Signed-off-by: Jan Kara <jack@suse.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
---

diff --git a/drivers/block/brd.c b/drivers/block/brd.c
index c9f9c30d6467..a5880f4ab40e 100644
--- a/drivers/block/brd.c
+++ b/drivers/block/brd.c
@@ -337,6 +337,9 @@ static blk_qc_t brd_make_request(struct request_queue *q, struct bio *bio)
 		goto io_error;
 
 	if (unlikely(bio->bi_rw & REQ_DISCARD)) {
+		if (sector & ((PAGE_SIZE >> SECTOR_SHIFT) - 1) ||
+		    bio->bi_iter.bi_size & PAGE_MASK)
+			goto io_error;
 		discard_from_brd(brd, sector, bio->bi_iter.bi_size);
 		goto out;
 	}