From b01cd5ac43b00c49759c126c21e7d22c7e80b245 Mon Sep 17 00:00:00 2001
From: Mikulas Patocka <mpatocka@redhat.com>
Date: Wed, 1 Oct 2008 14:39:24 +0100
Subject: [PATCH] dm: cope with access beyond end of device in dm_merge_bvec

If for any reason dm_merge_bvec() is given an offset beyond the end of the
device, avoid an oops and always allow one page to be added to an empty bio.
We'll reject the I/O later after the bio is submitted.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
---
 drivers/md/dm.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 469cec54f37..ace998ce59f 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -843,6 +843,8 @@ static int dm_merge_bvec(struct request_queue *q,
 		goto out;
 
 	ti = dm_table_find_target(map, bvm->bi_sector);
+	if (!dm_target_is_valid(ti))
+		goto out_table;
 
 	/*
 	 * Find maximum amount of I/O that won't need splitting
@@ -861,6 +863,7 @@ static int dm_merge_bvec(struct request_queue *q,
 	if (max_size && ti->type->merge)
 		max_size = ti->type->merge(ti, bvm, biovec, max_size);
 
+out_table:
 	dm_table_put(map);
 
 out:
-- 
2.41.3