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-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <20230927164715.76744-3-joao@overdrivepizza.com>
Date:   Wed, 27 Sep 2023 09:47:15 -0700
From:   joao@...rdrivepizza.com
To:     pablo@...filter.org, netfilter-devel@...r.kernel.org,
        coreteam@...filter.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, joao@...rdrivepizza.com
Cc:     kadlec@...filter.org, fw@...len.de, davem@...emloft.net,
        edumazet@...gle.com, kuba@...nel.org, pabeni@...hat.com,
        rkannoth@...vell.com, wojciech.drewek@...el.com,
        steen.hegenlund@...rohip.com, keescook@...omium.org,
        Joao Moreira <joao.moreira@...el.com>
Subject: [PATCH v3 2/2] Make num_actions unsigned

From: Joao Moreira <joao.moreira@...el.com>

Currently, in nft_flow_rule_create function, num_actions is a signed
integer. Yet, it is processed within a loop which increments its
value. To prevent an overflow from occurring, make it unsigned and
also check if it reaches 256 when being incremented.

Accordingly to discussions around v2, 256 actions are more than enough
for the frontend actions.

After checking with maintainers, it was mentioned that front-end will
cap the num_actions value and that it is not possible to reach such
condition for an overflow. Yet, for correctness, it is still better to
fix this.

This issue was observed by the commit author while reviewing a write-up
regarding a CVE within the same subsystem [1].

1 - https://nickgregory.me/post/2022/03/12/cve-2022-25636/

Signed-off-by: Joao Moreira <joao.moreira@...el.com>
---
 net/netfilter/nf_tables_offload.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/net/netfilter/nf_tables_offload.c b/net/netfilter/nf_tables_offload.c
index 12ab78fa5d84..9a86db1f0e07 100644
--- a/net/netfilter/nf_tables_offload.c
+++ b/net/netfilter/nf_tables_offload.c
@@ -90,7 +90,8 @@ struct nft_flow_rule *nft_flow_rule_create(struct net *net,
 {
 	struct nft_offload_ctx *ctx;
 	struct nft_flow_rule *flow;
-	int num_actions = 0, err;
+	unsigned int num_actions = 0;
+	int err;
 	struct nft_expr *expr;
 
 	expr = nft_expr_first(rule);
@@ -99,6 +100,10 @@ struct nft_flow_rule *nft_flow_rule_create(struct net *net,
 		    expr->ops->offload_action(expr))
 			num_actions++;
 
+		/* 2^8 is enough for frontend actions, avoid overflow */
+		if (num_actions == 256)
+			return ERR_PTR(-ENOMEM);
+
 		expr = nft_expr_next(expr);
 	}
 
-- 
2.42.0

Powered by blists - more mailing lists

Powered by Openwall GNU/*/Linux Powered by OpenVZ