linux-kernel - [PATCH] netfilter: nf_tables: Add a null pointer check in two functions

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Date: Tue, 23 Jan 2024 14:45:12 +0100
From: Markus Elfring <Markus.Elfring@....de>
To: netfilter-devel@...r.kernel.org, coreteam@...filter.org,
 netdev@...r.kernel.org, kernel-janitors@...r.kernel.org,
 "David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>,
 Florian Westphal <fw@...len.de>, Jakub Kicinski <kuba@...nel.org>,
 Jozsef Kadlecsik <kadlec@...filter.org>,
 Pablo Neira Ayuso <pablo@...filter.org>, Paolo Abeni <pabeni@...hat.com>,
 Phil Sutter <phil@....cc>
Cc: LKML <linux-kernel@...r.kernel.org>, Kunwu Chan <chentao@...inos.cn>
Subject: [PATCH] netfilter: nf_tables: Add a null pointer check in two
 functions

From: Markus Elfring <elfring@...rs.sourceforge.net>
Date: Tue, 23 Jan 2024 14:28:31 +0100

The result from a call of the function “kasprintf” was passed to
a subsequent function call without checking for a null pointer before
(according to a memory allocation failure).
This issue was detected by using the Coccinelle software.

Thus add a null pointer check and a jump target in affected functions.

Fixes: 8877393029e76 ("netfilter: nf_tables: Open-code audit log call in nf_tables_getrule()")
Fixes: 0854db2aaef3f ("netfilter: nf_tables: use net_generic infra for transaction data")
Signed-off-by: Markus Elfring <elfring@...rs.sourceforge.net>
---
 net/netfilter/nf_tables_api.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index 8438a8922e4a..cb61c7a39a76 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -3728,10 +3728,13 @@ static int nf_tables_getrule_reset(struct sk_buff *skb,
 			nla_len(nla[NFTA_RULE_TABLE]),
 			(char *)nla_data(nla[NFTA_RULE_TABLE]),
 			nft_net->base_seq);
+	if (!buf)
+		goto exit;
+
 	audit_log_nfcfg(buf, info->nfmsg->nfgen_family, 1,
 			AUDIT_NFT_OP_RULE_RESET, GFP_ATOMIC);
 	kfree(buf);
-
+exit:
 	return nfnetlink_unicast(skb2, net, portid);
 }

@@ -7917,6 +7920,8 @@ static int nf_tables_getobj(struct sk_buff *skb, const struct nfnl_info *info,

 		nft_net = nft_pernet(net);
 		buf = kasprintf(GFP_ATOMIC, "%s:%u", table->name, nft_net->base_seq);
+		if (!buf)
+			goto fill_obj_info;

 		audit_log_nfcfg(buf,
 				family,
@@ -7925,7 +7930,7 @@ static int nf_tables_getobj(struct sk_buff *skb, const struct nfnl_info *info,
 				GFP_ATOMIC);
 		kfree(buf);
 	}
-
+fill_obj_info:
 	err = nf_tables_fill_obj_info(skb2, net, NETLINK_CB(skb).portid,
 				      info->nlh->nlmsg_seq, NFT_MSG_NEWOBJ, 0,
 				      family, table, obj, reset);
--
2.43.0