linux-kernel - [PATCH v4 ipsec-next] xfrm: remove VLA usage in __xfrm6

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Message-ID: <20180425144639.GA38350@beast>
Date:   Wed, 25 Apr 2018 07:46:39 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Stefano Brivio <sbrivio@...hat.com>
Cc:     Andreas Christoforou <andreaschristofo@...il.com>,
        kernel-hardening@...ts.openwall.com,
        Steffen Klassert <steffen.klassert@...unet.com>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        "David S. Miller" <davem@...emloft.net>,
        Alexey Kuznetsov <kuznet@....inr.ac.ru>,
        Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH v4 ipsec-next] xfrm: remove VLA usage in __xfrm6_sort()

In the quest to remove all stack VLA usage removed from the kernel[1],
just use XFRM_MAX_DEPTH as already done for the "class" array. In one
case, it'll do this loop up to 5, the other caller up to 6.

[1] https://lkml.org/lkml/2018/3/7/621

Co-developed-by: Andreas Christoforou <andreaschristofo@...il.com>
Signed-off-by: Kees Cook <keescook@...omium.org>
---
v4:
- actually remove memset(). :)
v3:
- adjust Subject and commit log (Steffen)
- use "= { }" instead of memset() (Stefano)
v2:
- use XFRM_MAX_DEPTH for "count" array (Steffen and Mathias).
---
 net/ipv6/xfrm6_state.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/net/ipv6/xfrm6_state.c b/net/ipv6/xfrm6_state.c
index 16f434791763..5bdca3d5d6b7 100644
--- a/net/ipv6/xfrm6_state.c
+++ b/net/ipv6/xfrm6_state.c
@@ -60,11 +60,9 @@ xfrm6_init_temprop(struct xfrm_state *x, const struct xfrm_tmpl *tmpl,
 static int
 __xfrm6_sort(void **dst, void **src, int n, int (*cmp)(void *p), int maxclass)
 {
-	int i;
+	int count[XFRM_MAX_DEPTH] = { };
 	int class[XFRM_MAX_DEPTH];
-	int count[maxclass];
-
-	memset(count, 0, sizeof(count));
+	int i;
 
 	for (i = 0; i < n; i++) {
 		int c;
-- 
2.7.4


-- 
Kees Cook
Pixel Security