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

bed31ed9 · Andy Isaacson <[email protected]> · 2007-03-16 13:38:04 -08:00

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

Cc: Gautham R Shenoy <[email protected]>
Acked-by: Neil Brown <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

Commit: bed31ed9e1cd71d98ff0bc9212100adee523a10a
Parents: 48670a1e

Changes

1 files changed · +1 −1

File	Status	Add	Del	Content
drivers/md/linear.c	modified	+1	−1	View file

drivers/md/linear.c

View file

diff --git a/drivers/md/linear.c b/drivers/md/linear.c
index c625ddb..d5ecd2d 100644
--- a/drivers/md/linear.c
+++ b/drivers/md/linear.c
@@ -188,7 +188,7 @@ static linear_conf_t *linear_conf(mddev_t *mddev, int raid_disks)
 	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;