[PATCH 06/10] ipc: Don't allocate a copy larger than max

[Peter Hurley <peter@hurleysoftware.com>]

When MSG_COPY is set, a duplicate message must be allocated for
the copy before locking the queue. However, the copy could
not be larger than was sent which is limited to msg_ctlmax.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
---
 ipc/msg.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/ipc/msg.c b/ipc/msg.c
index 950572f..31cd1bf 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)) {
-- 
1.8.1.2