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>

diff --git a/ipc/compat.c b/ipc/compat.c
index f71e962756d815230b9c9dea727b1be63f009445..f486b0096a67f32fe453cca13b40ad6268a76d45 100644 (file)
--- 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: