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 <[email protected]>
Reported-by: Gabriellla Schmidt <[email protected]>
Cc: Al Viro <[email protected]>
Cc: Davidlohr Bueso <[email protected]>
Cc: Manfred Spraul <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

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: