[ 086/109] net: Fix references to out-of-scope variables in put_cmsg_compat()

From: Greg Kroah-Hartman
Date: Tue Aug 07 2012 - 18:40:43 EST


From: Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx>

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

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


From: Jesper Juhl <jj@xxxxxxxxxxxxx>

[ 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@xxxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
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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