From 01c03ebd64e8a7bedbb8ae2743b42a4c676da2b4 Mon Sep 17 00:00:00 2001 From: Arnd Bergmann Date: Tue, 22 Sep 2020 10:14:56 +0800 Subject: [PATCH] netfilter: nf_osf: avoid passing pointer to local var stable inclusion from linux-4.19.123 commit 412cb7a3fb66792f8ec30ed80e126193ad073e56 -------------------------------- 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 Reviewed-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso Signed-off-by: Greg Kroah-Hartman Signed-off-by: Yang Yingliang Signed-off-by: Li Aichun Reviewed-by: guodeqing Signed-off-by: Yang Yingliang --- net/netfilter/nfnetlink_osf.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) diff --git a/net/netfilter/nfnetlink_osf.c b/net/netfilter/nfnetlink_osf.c index b0bc130947c9..131f9f8c0b09 100644 --- a/net/netfilter/nfnetlink_osf.c +++ b/net/netfilter/nfnetlink_osf.c @@ -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; -- GitLab