From ef5c96e91ae55745e6759bdc7a0ef99c5ef11475 Mon Sep 17 00:00:00 2001
From: Young Xiao <92siuyang@gmail.com>
Date: Thu, 16 May 2019 20:09:23 +0800
Subject: [PATCH] Prevent kernel stack disclosure in swapcontext.

This is the vulnerability that is same with CVE-2018-17155.

Signed-off-by: Young Xiao <92siuyang@gmail.com>
---
 sys/arm64/arm64/freebsd32_machdep.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/sys/arm64/arm64/freebsd32_machdep.c b/sys/arm64/arm64/freebsd32_machdep.c
index a6719b6..aeac460 100644
--- a/sys/arm64/arm64/freebsd32_machdep.c
+++ b/sys/arm64/arm64/freebsd32_machdep.c
@@ -284,6 +284,7 @@ freebsd32_swapcontext(struct thread *td, struct freebsd32_swapcontext_args *uap)
 	if (uap->oucp == NULL || uap->ucp == NULL)
 		ret = EINVAL;
 	else {
+		bzero(&uc, sizeof(uc));
 		get_mcontext32(td, &uc.uc_mcontext, GET_MC_CLEAR_RET);
 		PROC_LOCK(td->td_proc);
 		uc.uc_sigmask = td->td_sigmask;
-- 
2.7.4