From: Will Deacon <will.deacon@arm.com>
Date: Mon, 30 Jul 2012 21:42:43 +0000 (-0700)
Subject: ipc: compat: use signed size_t types for msgsnd and msgrcv
X-Git-Tag: v3.6-rc1~41^2~17
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=05ba3f1aa1b04e921068249dd52a80bc84c2aeb4;p=pandora-kernel.git

ipc: compat: use signed size_t types for msgsnd and msgrcv

The msgsnd and msgrcv system calls use size_t to represent the size of the
message being transferred.  POSIX states that values of msgsz greater than
SSIZE_MAX cause the result to be implementation-defined.  On Linux, this
equates to returning -EINVAL if (long) msgsz < 0.

For compat tasks where !CONFIG_ARCH_WANT_OLD_COMPAT_IPC and compat_size_t
is smaller than size_t, negative size values passed from userspace will be
interpreted as positive values by do_msg{rcv,snd} and will fail to exit
early with -EINVAL.

This patch changes the compat prototypes for msg{rcv,snd} so that the
message size is represented as a compat_ssize_t, which we cast to the
native ssize_t type for the core IPC code.

Cc: Arnd Bergmann <arnd@arndb.de>
Acked-by: Chris Metcalf <cmetcalf@tilera.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

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