linux-kernel - [PATCH 4.19 45/48] netfilter: nf_osf: avoid passing pointer to local var

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: <20200513094404.213164359@linuxfoundation.org>
Date:   Wed, 13 May 2020 11:45:11 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Arnd Bergmann <arnd@...db.de>,
        Florian Westphal <fw@...len.de>,
        Pablo Neira Ayuso <pablo@...filter.org>
Subject: [PATCH 4.19 45/48] netfilter: nf_osf: avoid passing pointer to local var

From: Arnd Bergmann <arnd@...db.de>

commit c165d57b552aaca607fa5daf3fb524a6efe3c5a3 upstream.

gcc-10 points out that a code path exists where a pointer to a stack
variable may be passed back to the caller:

net/netfilter/nfnetlink_osf.c: In function 'nf_osf_hdr_ctx_init':
cc1: warning: function may return address of local variable [-Wreturn-local-addr]
net/netfilter/nfnetlink_osf.c:171:16: note: declared here
  171 |  struct tcphdr _tcph;
      |                ^~~~~

I am not sure whether this can happen in practice, but moving the
variable declaration into the callers avoids the problem.

Fixes: 31a9c29210e2 ("netfilter: nf_osf: add struct nf_osf_hdr_ctx")
Signed-off-by: Arnd Bergmann <arnd@...db.de>
Reviewed-by: Florian Westphal <fw@...len.de>
Signed-off-by: Pablo Neira Ayuso <pablo@...filter.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 net/netfilter/nfnetlink_osf.c |   12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

--- a/net/netfilter/nfnetlink_osf.c
+++ b/net/netfilter/nfnetlink_osf.c
@@ -170,12 +170,12 @@ static bool nf_osf_match_one(const struc
 static const struct tcphdr *nf_osf_hdr_ctx_init(struct nf_osf_hdr_ctx *ctx,
 						const struct sk_buff *skb,
 						const struct iphdr *ip,
-						unsigned char *opts)
+						unsigned char *opts,
+						struct tcphdr *_tcph)
 {
 	const struct tcphdr *tcp;
-	struct tcphdr _tcph;
 
-	tcp = skb_header_pointer(skb, ip_hdrlen(skb), sizeof(struct tcphdr), &_tcph);
+	tcp = skb_header_pointer(skb, ip_hdrlen(skb), sizeof(struct tcphdr), _tcph);
 	if (!tcp)
 		return NULL;
 
@@ -210,10 +210,11 @@ nf_osf_match(const struct sk_buff *skb,
 	int fmatch = FMATCH_WRONG;
 	struct nf_osf_hdr_ctx ctx;
 	const struct tcphdr *tcp;
+	struct tcphdr _tcph;
 
 	memset(&ctx, 0, sizeof(ctx));
 
-	tcp = nf_osf_hdr_ctx_init(&ctx, skb, ip, opts);
+	tcp = nf_osf_hdr_ctx_init(&ctx, skb, ip, opts, &_tcph);
 	if (!tcp)
 		return false;
 
@@ -270,10 +271,11 @@ const char *nf_osf_find(const struct sk_
 	struct nf_osf_hdr_ctx ctx;
 	const struct tcphdr *tcp;
 	const char *genre = NULL;
+	struct tcphdr _tcph;
 
 	memset(&ctx, 0, sizeof(ctx));
 
-	tcp = nf_osf_hdr_ctx_init(&ctx, skb, ip, opts);
+	tcp = nf_osf_hdr_ctx_init(&ctx, skb, ip, opts, &_tcph);
 	if (!tcp)
 		return NULL;