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ipc: don't allocate a copy larger than max

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>
Acked-by: Stanislav Kinsbursky <skinsbursky@parallels.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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1 parent e1082f4 commit 88b9e456b1649722673ffa147914299799dc9041 @peterhurley peterhurley committed with
Showing with 4 additions and 2 deletions.
  1. +4 −2 ipc/msg.c
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6 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)) {

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