linux-kernel - Re: [PATCH] netfilter: nf_osf: avoid passing pointer to local var

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Message-ID: <20200429191256.GL32392@breakpoint.cc>
Date:   Wed, 29 Apr 2020 21:12:56 +0200
From:   Florian Westphal <fw@...len.de>
To:     Arnd Bergmann <arnd@...db.de>
Cc:     Pablo Neira Ayuso <pablo@...filter.org>,
        Jozsef Kadlecsik <kadlec@...filter.org>,
        Florian Westphal <fw@...len.de>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        netfilter-devel@...r.kernel.org, coreteam@...filter.org,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] netfilter: nf_osf: avoid passing pointer to local var

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

LGTM, thanks Arnd.

Reviewed-by: Florian Westphal <fw@...len.de>