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Commit 412cb7a3 authored by Arnd Bergmann's avatar Arnd Bergmann Committed by Greg Kroah-Hartman
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netfilter: nf_osf: avoid passing pointer to local var 



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: 31a9c292 ("netfilter: nf_osf: add struct nf_osf_hdr_ctx")
Signed-off-by: default avatarArnd Bergmann <arnd@arndb.de>
Reviewed-by: default avatarFlorian Westphal <fw@strlen.de>
Signed-off-by: default avatarPablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent efc97a1d

net/netfilter/nfnetlink_osf.c

+7 −5
Original line number Diff line number Diff line
@@ -170,12 +170,12 @@ static bool nf_osf_match_one(const struct sk_buff *skb, 
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, u_int8_t family, 
	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_buff *skb, 
	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;