linux-kernel - [PATCH net-next] netfilter: nf_tables: avoid excessive stack usage

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: Windows password security audit tool. GUI, reports in PDF.

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

Message-Id: <20190906151242.1115282-1-arnd@arndb.de>
Date:   Fri,  6 Sep 2019 17:12:30 +0200
From:   Arnd Bergmann <arnd@...db.de>
To:     Pablo Neira Ayuso <pablo@...filter.org>,
        Jozsef Kadlecsik <kadlec@...filter.org>,
        Florian Westphal <fw@...len.de>,
        "David S. Miller" <davem@...emloft.net>
Cc:     Arnd Bergmann <arnd@...db.de>,
        Jakub Kicinski <jakub.kicinski@...ronome.com>,
        wenxu <wenxu@...oud.cn>, netfilter-devel@...r.kernel.org,
        coreteam@...filter.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH net-next] netfilter: nf_tables: avoid excessive stack usage

The nft_offload_ctx structure is much too large to put on the
stack:

net/netfilter/nf_tables_offload.c:31:23: error: stack frame size of 1200 bytes in function 'nft_flow_rule_create' [-Werror,-Wframe-larger-than=]

Use dynamic allocation here, as we do elsewhere in the same
function.

Fixes: c9626a2cbdb2 ("netfilter: nf_tables: add hardware offload support")
Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
Since we only really care about two members of the structure, an
alternative would be a larger rewrite, but that is probably too
late for v5.4.
---
 net/netfilter/nf_tables_offload.c | 22 +++++++++++++++-------
 1 file changed, 15 insertions(+), 7 deletions(-)

diff --git a/net/netfilter/nf_tables_offload.c b/net/netfilter/nf_tables_offload.c
index 3c2725ade61b..c94331aae552 100644
--- a/net/netfilter/nf_tables_offload.c
+++ b/net/netfilter/nf_tables_offload.c
@@ -30,15 +30,13 @@ static struct nft_flow_rule *nft_flow_rule_alloc(int num_actions)
 
 struct nft_flow_rule *nft_flow_rule_create(const struct nft_rule *rule)
 {
-	struct nft_offload_ctx ctx = {
-		.dep	= {
-			.type	= NFT_OFFLOAD_DEP_UNSPEC,
-		},
-	};
+	struct nft_offload_ctx *ctx;
+
 	struct nft_flow_rule *flow;
 	int num_actions = 0, err;
 	struct nft_expr *expr;
 
+
 	expr = nft_expr_first(rule);
 	while (expr->ops && expr != nft_expr_last(rule)) {
 		if (expr->ops->offload_flags & NFT_OFFLOAD_F_ACTION)
@@ -52,21 +50,31 @@ struct nft_flow_rule *nft_flow_rule_create(const struct nft_rule *rule)
 		return ERR_PTR(-ENOMEM);
 
 	expr = nft_expr_first(rule);
+
+	ctx = kzalloc(sizeof(struct nft_offload_ctx), GFP_KERNEL);
+	if (!ctx) {
+		err = -ENOMEM;
+		goto err_out;
+	}
+	ctx->dep.type = NFT_OFFLOAD_DEP_UNSPEC;
+
 	while (expr->ops && expr != nft_expr_last(rule)) {
 		if (!expr->ops->offload) {
 			err = -EOPNOTSUPP;
 			goto err_out;
 		}
-		err = expr->ops->offload(&ctx, flow, expr);
+		err = expr->ops->offload(ctx, flow, expr);
 		if (err < 0)
 			goto err_out;
 
 		expr = nft_expr_next(expr);
 	}
-	flow->proto = ctx.dep.l3num;
+	flow->proto = ctx->dep.l3num;
+	kfree(ctx);
 
 	return flow;
 err_out:
+	kfree(ctx);
 	nft_flow_rule_destroy(flow);
 
 	return ERR_PTR(err);
-- 
2.20.0