From e7ca2552369c1dfe0216c626baf82c3d83ec36bb Mon Sep 17 00:00:00 2001
From: Mateusz Guzik <mguzik@redhat.com>
Date: Mon, 27 Jan 2014 17:07:11 -0800
Subject: [PATCH] ipc: fix compat msgrcv with negative msgtyp

Compat function takes msgtyp argument as u32 and passes it down to
do_msgrcv which results in casting to long, thus the sign is lost and we
get a big positive number instead.

Cast the argument to signed type before passing it down.

Signed-off-by: Mateusz Guzik <mguzik@redhat.com>
Reported-by: Gabriellla Schmidt <gsc@bruker.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Davidlohr Bueso <davidlohr@hp.com>
Cc: Manfred Spraul <manfred@colorfullife.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 ipc/compat.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/ipc/compat.c b/ipc/compat.c
index f71e962756d8..f486b0096a67 100644
--- a/ipc/compat.c
+++ b/ipc/compat.c
@@ -381,7 +381,7 @@ COMPAT_SYSCALL_DEFINE6(ipc, u32, call, int, first, int, second,
 			uptr = compat_ptr(ipck.msgp);
 			fifth = ipck.msgtyp;
 		}
-		return do_msgrcv(first, uptr, second, fifth, third,
+		return do_msgrcv(first, uptr, second, (s32)fifth, third,
 				 compat_do_msg_fill);
 	}
 	case MSGGET:
-- 
2.20.1