[PATCH 2/2] devcgroup: fix permission check when adding entry to child cgroup

[Li Zefan <lizf@cn.fujitsu.com>]

 # cat devices.list
 c 1:3 r
 # echo 'c 1:3 w' > sub/devices.allow
 # cat sub/devices.list
 c 1:3 w

As illustrated, the parent group has no write permission to /dev/null,
so its child should not be allowed to add this write permission,
which is documented in Documentation/controllers/devices.txt.

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
---
 security/device_cgroup.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/security/device_cgroup.c b/security/device_cgroup.c
index 1e2e28a..ddd92ce 100644
--- a/security/device_cgroup.c
+++ b/security/device_cgroup.c
@@ -300,7 +300,7 @@ static int may_access_whitelist(struct dev_cgroup *c,
 			continue;
 		if (whitem->minor != ~0 && whitem->minor != refwh->minor)
 			continue;
-		if (refwh->access & (~(whitem->access | ACC_MASK)))
+		if (refwh->access & (~whitem->access))
 			continue;
 		return 1;
 	}
-- 
1.5.4.rc3