net: fix info leak in compat dev_ifconf()

[ Upstream commit 43da5f2e0d ]

The implementation of dev_ifconf() for the compat ioctl interface uses
an intermediate ifc structure allocated in userland for the duration of
the syscall. Though, it fails to initialize the padding bytes inserted
for alignment and that for leaks four bytes of kernel stack. Add an
explicit memset(0) before filling the structure to avoid the info leak.

Signed-off-by: Mathias Krause <minipli@googlemail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Mathias Krause
2012-08-15 11:31:57 +00:00
committed by Greg Kroah-Hartman
parent b56518548a
commit 7a62b446c6

View File

@@ -2645,6 +2645,7 @@ static int dev_ifconf(struct net *net, struct compat_ifconf __user *uifc32)
if (copy_from_user(&ifc32, uifc32, sizeof(struct compat_ifconf)))
return -EFAULT;
memset(&ifc, 0, sizeof(ifc));
if (ifc32.ifcbuf == 0) {
ifc32.ifc_len = 0;
ifc.ifc_len = 0;