[3.16.y-ckt stable] Patch "net: compat: Update get_compat_msghdr() to match copy_msghdr_from_user() behaviour" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    net: compat: Update get_compat_msghdr() to match copy_msghdr_from_user() behaviour

to the linux-3.16.y-queue branch of the 3.16.y-ckt extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.16.y-queue

This patch is scheduled to be released in version 3.16.7-ckt9.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.16.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From f5b93a1a1361eae0e00d418e0166d6867f4c0050 Mon Sep 17 00:00:00 2001
From: Catalin Marinas <catalin.marinas at arm.com>
Date: Fri, 20 Mar 2015 16:48:13 +0000
Subject: net: compat: Update get_compat_msghdr() to match
 copy_msghdr_from_user() behaviour

commit 91edd096e224941131f896b86838b1e59553696a upstream.

Commit db31c55a6fb2 (net: clamp ->msg_namelen instead of returning an
error) introduced the clamping of msg_namelen when the unsigned value
was larger than sizeof(struct sockaddr_storage). This caused a
msg_namelen of -1 to be valid. The native code was subsequently fixed by
commit dbb490b96584 (net: socket: error on a negative msg_namelen).

In addition, the native code sets msg_namelen to 0 when msg_name is
NULL. This was done in commit (6a2a2b3ae075 net:socket: set msg_namelen
to 0 if msg_name is passed as NULL in msghdr struct from userland) and
subsequently updated by 08adb7dabd48 (fold verify_iovec() into
copy_msghdr_from_user()).

This patch brings the get_compat_msghdr() in line with
copy_msghdr_from_user().

Fixes: db31c55a6fb2 (net: clamp ->msg_namelen instead of returning an error)
Cc: David S. Miller <davem at davemloft.net>
Cc: Dan Carpenter <dan.carpenter at oracle.com>
Signed-off-by: Catalin Marinas <catalin.marinas at arm.com>
Signed-off-by: David S. Miller <davem at davemloft.net>
[ luis: backported to 3.16: used davem's backport to 3.14 ]
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 net/compat.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/net/compat.c b/net/compat.c
index c48930373e65..53e933eb78b8 100644
--- a/net/compat.c
+++ b/net/compat.c
@@ -71,6 +71,13 @@ int get_compat_msghdr(struct msghdr *kmsg, struct compat_msghdr __user *umsg)
 	    __get_user(kmsg->msg_controllen, &umsg->msg_controllen) ||
 	    __get_user(kmsg->msg_flags, &umsg->msg_flags))
 		return -EFAULT;
+
+	if (!tmp1)
+		kmsg->msg_namelen = 0;
+
+	if (kmsg->msg_namelen < 0)
+		return -EINVAL;
+
 	if (kmsg->msg_namelen > sizeof(struct sockaddr_storage))
 		kmsg->msg_namelen = sizeof(struct sockaddr_storage);
 	kmsg->msg_name = compat_ptr(tmp1);