netdev - [PATCH 38/64] xfrm: Use memset

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20210727205855.411487-39-keescook@chromium.org>
Date:   Tue, 27 Jul 2021 13:58:29 -0700
From:   Kees Cook <keescook@...omium.org>
To:     linux-hardening@...r.kernel.org
Cc:     Kees Cook <keescook@...omium.org>,
        "Gustavo A. R. Silva" <gustavoars@...nel.org>,
        Keith Packard <keithpac@...zon.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        linux-kernel@...r.kernel.org, linux-wireless@...r.kernel.org,
        netdev@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        linux-staging@...ts.linux.dev, linux-block@...r.kernel.org,
        linux-kbuild@...r.kernel.org, clang-built-linux@...glegroups.com
Subject: [PATCH 38/64] xfrm: Use memset_after() to clear padding

In preparation for FORTIFY_SOURCE performing compile-time and run-time
field bounds checking for memset(), avoid intentionally writing across
neighboring fields.

Clear trailing padding bytes using the new helper so that memset()
doesn't get confused about writing "past the end" of the last struct
member. There is no change to the resulting machine code.

Signed-off-by: Kees Cook <keescook@...omium.org>
---
 net/xfrm/xfrm_policy.c | 4 +---
 net/xfrm/xfrm_user.c   | 2 +-
 2 files changed, 2 insertions(+), 4 deletions(-)

diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
index 37d17a79617c..1a06585022ab 100644
--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -2486,9 +2486,7 @@ static inline struct xfrm_dst *xfrm_alloc_dst(struct net *net, int family)
 	xdst = dst_alloc(dst_ops, NULL, 1, DST_OBSOLETE_NONE, 0);
 
 	if (likely(xdst)) {
-		struct dst_entry *dst = &xdst->u.dst;
-
-		memset(dst + 1, 0, sizeof(*xdst) - sizeof(*dst));
+		memset_after(xdst, 0, u.dst);
 	} else
 		xdst = ERR_PTR(-ENOBUFS);
 
diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c
index acc3a0dab331..0bf8fec3fd97 100644
--- a/net/xfrm/xfrm_user.c
+++ b/net/xfrm/xfrm_user.c
@@ -2907,7 +2907,7 @@ static int build_expire(struct sk_buff *skb, struct xfrm_state *x, const struct
 	copy_to_user_state(x, &ue->state);
 	ue->hard = (c->data.hard != 0) ? 1 : 0;
 	/* clear the padding bytes */
-	memset(&ue->hard + 1, 0, sizeof(*ue) - offsetofend(typeof(*ue), hard));
+	memset_after(ue, 0, hard);
 
 	err = xfrm_mark_put(skb, &x->mark);
 	if (err)
-- 
2.30.2