From: Andy Isaacson <adi@hexapodia.org>
Date: Mon, 26 Mar 2007 21:42:40 +0000 (+0200)
Subject: fix read past end of array in md/linear.c
X-Git-Tag: v2.6.16.46-rc1~24
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=36c8a3d3ac8b0157ea4ebc54926d40309787a865;p=thirdparty%2Fkernel%2Fstable.git

fix read past end of array in md/linear.c

When iterating through an array, one must be careful to test one's index
variable rather than another similarly-named variable.

The loop will read off the end of conf->disks[] in the following
(pathological) case:

% dd bs=1 seek=840716287 if=/dev/zero of=d1 count=1
% for i in 2 3 4; do dd if=/dev/zero of=d$i bs=1k count=$(($i+150)); done
% ./vmlinux ubd0=root ubd1=d1 ubd2=d2 ubd3=d3 ubd4=d4
# mdadm -C /dev/md0 --level=linear --raid-devices=4 /dev/ubd[1234]

adding some printks, I saw this:
[42949374.960000] hash_spacing = 821120
[42949374.960000] cnt          = 4
[42949374.960000] min_spacing  = 801
[42949374.960000] j=0 size=820928 sz=820928
[42949374.960000] i=0 sz=820928 hash_spacing=820928
[42949374.960000] j=1 size=64 sz=64
[42949374.960000] j=2 size=64 sz=128
[42949374.960000] j=3 size=64 sz=192
[42949374.960000] j=4 size=1515870810 sz=1515871002

Signed-off-by: Adrian Bunk <bunk@stusta.de>
---

diff --git a/drivers/md/linear.c b/drivers/md/linear.c
index 777585458c852..0fa9e685578ca 100644
--- a/drivers/md/linear.c
+++ b/drivers/md/linear.c
@@ -174,7 +174,7 @@ static int linear_run (mddev_t *mddev)
 	for (i=0; i < cnt-1 ; i++) {
 		sector_t sz = 0;
 		int j;
-		for (j=i; i<cnt-1 && sz < min_spacing ; j++)
+		for (j = i; j < cnt - 1 && sz < min_spacing; j++)
 			sz += conf->disks[j].size;
 		if (sz >= min_spacing && sz < conf->hash_spacing)
 			conf->hash_spacing = sz;