3 files changed, 16 insertions, 8 deletions

diff --git a/ipc/mqueue.c b/ipc/mqueue.c
index e5c4f609f22c..e4e47f647446 100644
--- a/ipc/mqueue.c
+++ b/ipc/mqueue.c
@@ -330,8 +330,16 @@ static struct dentry *mqueue_mount(struct file_system_type *fs_type,
                          int flags, const char *dev_name,
                          void *data)
 {
-        if (!(flags & MS_KERNMOUNT))
-                data = current->nsproxy->ipc_ns;
+        if (!(flags & MS_KERNMOUNT)) {
+                struct ipc_namespace *ns = current->nsproxy->ipc_ns;
+                /* Don't allow mounting unless the caller has CAP_SYS_ADMIN
+                 * over the ipc namespace.
+                 */
+                if (!ns_capable(ns->user_ns, CAP_SYS_ADMIN))
+                        return ERR_PTR(-EPERM);
+
+                data = ns;
+        }
         return mount_ns(fs_type, flags, data, mqueue_fill_super);
 }
 
@@ -840,7 +848,8 @@ out_putfd:
                 fd = error;
         }
         mutex_unlock(&root->d_inode->i_mutex);
-        mnt_drop_write(mnt);
+        if (!ro)
+                mnt_drop_write(mnt);
 out_putname:
         putname(name);
         return fd;
diff --git a/ipc/msg.c b/ipc/msg.c
index 950572f9d796..31cd1bf6af27 100644
--- a/ipc/msg.c
+++ b/ipc/msg.c
@@ -820,15 +820,17 @@ long do_msgrcv(int msqid, void __user *buf, size_t bufsz, long msgtyp,
         struct msg_msg *copy = NULL;
         unsigned long copy_number = 0;
 
+        ns = current->nsproxy->ipc_ns;
+
         if (msqid < 0 || (long) bufsz < 0)
                 return -EINVAL;
         if (msgflg & MSG_COPY) {
-                copy = prepare_copy(buf, bufsz, msgflg, &msgtyp, &copy_number);
+                copy = prepare_copy(buf, min_t(size_t, bufsz, ns->msg_ctlmax),
+                                    msgflg, &msgtyp, &copy_number);
                 if (IS_ERR(copy))
                         return PTR_ERR(copy);
         }
         mode = convert_mode(&msgtyp, msgflg);
-        ns = current->nsproxy->ipc_ns;
 
         msq = msg_lock_check(ns, msqid);
         if (IS_ERR(msq)) {
diff --git a/ipc/msgutil.c b/ipc/msgutil.c
index ebfcbfa8b7f2..5df8e4bf1db0 100644
--- a/ipc/msgutil.c
+++ b/ipc/msgutil.c
@@ -117,9 +117,6 @@ struct msg_msg *copy_msg(struct msg_msg *src, struct msg_msg *dst)
         if (alen > DATALEN_MSG)
                 alen = DATALEN_MSG;
 
-        dst->next = NULL;
-        dst->security = NULL;
-
         memcpy(dst + 1, src + 1, alen);
 
         len -= alen;