From d851b216eb6879bbd34d7ddbab6ad53602fe61ec Mon Sep 17 00:00:00 2001
From: Ed Maste <emaste@FreeBSD.org>
Date: Wed, 4 Apr 2018 14:41:48 +0000
Subject: [PATCH] linux_ioctl_hdio: fix kernel memory disclosure

Stack-allocated struct linux_hd_big_geometry has undeclared padding
copied to userland.

admbugs:	765
Reported by:	Vlad Tsyrklevich
MFC after:	1 day
Security:	Kernel memory disclosure
Sponsored by:	The FreeBSD Foundation
---
 sys/compat/linux/linux_ioctl.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/sys/compat/linux/linux_ioctl.c b/sys/compat/linux/linux_ioctl.c
index 9c417fad79a..880aff267c4 100644
--- a/sys/compat/linux/linux_ioctl.c
+++ b/sys/compat/linux/linux_ioctl.c
@@ -253,6 +253,7 @@ linux_ioctl_hdio(struct thread *td, struct linux_ioctl_args *args)
 		} else if ((args->cmd & 0xffff) == LINUX_HDIO_GET_GEO_BIG) {
 			struct linux_hd_big_geometry hdbg;
 
+			memset(&hdbg, 0, sizeof(hdbg));
 			hdbg.cylinders = fwcylinders;
 			hdbg.heads = fwheads;
 			hdbg.sectors = fwsectors;