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netfilter: nf_osf: avoid passing pointer to local var 

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: 31a9c29210 ("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>
This commit is contained in:
Arnd Bergmann 2020-04-29 21:00:41 +02:00 committed by Pablo Neira Ayuso
parent ea64d8d6c6
commit c165d57b55
1 changed files with 7 additions and 5 deletions
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12
net/netfilter/nfnetlink_osf.c
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@ -165,12 +165,12 @@ 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;
@ -205,10 +205,11 @@ 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;
@ -265,10 +266,11 @@ bool nf_osf_find(const struct sk_buff *skb,
const struct nf_osf_finger *kf;
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;