[dm-devel] [PATCH] dm mpath: add check for count of groups to avoid wild pointer access

[tang.junhui at zte.com.cn]

From: "tang.junhui" <tang.junhui at zte.com.cn>

pg is not assigned to a group address when count of multipath groups
is zero in bypass_pg_num(), then it is used in bypass_pg(), which may
cause wild pointer access.

Signed-off-by: tang.junhui <tang.junhui at zte.com.cn>
---
 drivers/md/dm-mpath.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c
index d376dc8..8c1359c 100644
--- a/drivers/md/dm-mpath.c
+++ b/drivers/md/dm-mpath.c
@@ -1084,7 +1084,7 @@ static int switch_pg_num(struct multipath *m, const char *pgstr)
 	char dummy;
 
 	if (!pgstr || (sscanf(pgstr, "%u%c", &pgnum, &dummy) != 1) || !pgnum ||
-	    (pgnum > m->nr_priority_groups)) {
+	    !m->nr_priority_groups || (pgnum > m->nr_priority_groups)) {
 		DMWARN("invalid PG number supplied to switch_pg_num");
 		return -EINVAL;
 	}
-- 
2.8.1.windows.1