From: Mathias Krause Date: Wed, 15 Aug 2012 11:31:57 +0000 Subject: net: fix info leak in compat dev_ifconf() [ Upstream commit 43da5f2e0d0c69ded3d51907d9552310a6b545e8 ] 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 Signed-off-by: David S. Miller Signed-off-by: Ben Hutchings --- net/socket.c | 1 + 1 file changed, 1 insertion(+) diff --git a/net/socket.c b/net/socket.c index 273cbce..68879db 100644 --- a/net/socket.c +++ b/net/socket.c @@ -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;