linux-kernel - [ 100/122] net: Fix references to out-of-scope variables in put_cmsg

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Message-Id: <20120807221958.533537902@linuxfoundation.org>
Date:	Tue,  7 Aug 2012 15:26:28 -0700
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:	Greg KH <gregkh@...uxfoundation.org>,
	torvalds@...ux-foundation.org, akpm@...ux-foundation.org,
	alan@...rguk.ukuu.org.uk, Jesper Juhl <jj@...osbits.net>,
	"David S. Miller" <davem@...emloft.net>
Subject: [ 100/122] net: Fix references to out-of-scope variables in put_cmsg_compat()

From: Greg KH <gregkh@...uxfoundation.org>

3.5-stable review patch.  If anyone has any objections, please let me know.

------------------


From: Jesper Juhl <jj@...osbits.net>

[ Upstream commit 818810472b129004c16fc51bf0a570b60776bfb7 ]

In net/compat.c::put_cmsg_compat() we may assign 'data' the address of
either the 'ctv' or 'cts' local variables inside the 'if
(!COMPAT_USE_64BIT_TIME)' branch.

Those variables go out of scope at the end of the 'if' statement, so
when we use 'data' further down in 'copy_to_user(CMSG_COMPAT_DATA(cm),
data, cmlen - sizeof(struct compat_cmsghdr))' there's no telling what
it may be refering to - not good.

Fix the problem by simply giving 'ctv' and 'cts' function scope.

Signed-off-by: Jesper Juhl <jj@...osbits.net>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 net/compat.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/net/compat.c
+++ b/net/compat.c
@@ -221,6 +221,8 @@ int put_cmsg_compat(struct msghdr *kmsg,
 {
 	struct compat_cmsghdr __user *cm = (struct compat_cmsghdr __user *) kmsg->msg_control;
 	struct compat_cmsghdr cmhdr;
+	struct compat_timeval ctv;
+	struct compat_timespec cts[3];
 	int cmlen;
 
 	if (cm == NULL || kmsg->msg_controllen < sizeof(*cm)) {
@@ -229,8 +231,6 @@ int put_cmsg_compat(struct msghdr *kmsg,
 	}
 
 	if (!COMPAT_USE_64BIT_TIME) {
-		struct compat_timeval ctv;
-		struct compat_timespec cts[3];
 		if (level == SOL_SOCKET && type == SCM_TIMESTAMP) {
 			struct timeval *tv = (struct timeval *)data;
 			ctv.tv_sec = tv->tv_sec;


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