Messages in this thread Patch in this message | | | From | Greg Kroah-Hartman <> | Subject | [PATCH 4.19 45/48] netfilter: nf_osf: avoid passing pointer to local var | Date | Wed, 13 May 2020 11:45:11 +0200 |
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From: Arnd Bergmann <arnd@arndb.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@arndb.de> Reviewed-by: Florian Westphal <fw@strlen.de> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.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;
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