1 files changed, 12 insertions, 2 deletions

diff --git a/arch/s390/kernel/compat_linux.c b/arch/s390/kernel/compat_linux.c
index ab64bdbab2ae..f0273ed760ef 100644
--- a/arch/s390/kernel/compat_linux.c
+++ b/arch/s390/kernel/compat_linux.c
@@ -173,11 +173,14 @@ asmlinkage long sys32_setfsgid16(u16 gid)
 
 static int groups16_to_user(u16 __user *grouplist, struct group_info *group_info)
 {
+        struct user_namespace *user_ns = current_user_ns();
         int i;
         u16 group;
+        kgid_t kgid;
 
         for (i = 0; i < group_info->ngroups; i++) {
-                group = (u16)GROUP_AT(group_info, i);
+                kgid = GROUP_AT(group_info, i);
+                group = (u16)from_kgid_munged(user_ns, kgid);
                 if (put_user(group, grouplist+i))
                         return -EFAULT;
         }
@@ -187,13 +190,20 @@ static int groups16_to_user(u16 __user *grouplist, struct group_info *group_info
 
 static int groups16_from_user(struct group_info *group_info, u16 __user *grouplist)
 {
+        struct user_namespace *user_ns = current_user_ns();
         int i;
         u16 group;
+        kgid_t kgid;
 
         for (i = 0; i < group_info->ngroups; i++) {
                 if (get_user(group, grouplist+i))
                         return  -EFAULT;
-                GROUP_AT(group_info, i) = (gid_t)group;
+
+                kgid = make_kgid(user_ns, (gid_t)group);
+                if (!gid_valid(kgid))
+                        return -EINVAL;
+
+                GROUP_AT(group_info, i) = kgid;
         }
 
         return 0;