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Date: Mon, 7 Sep 2026 10:33:20 +0200
From: Florian Westphal <fw@strlen.de>
To: Aamir Ahmed <elb12345@hotmail.co.uk>
Cc: Pablo Neira Ayuso <pablo@netfilter.org>,
	netfilter-devel@vger.kernel.org, coreteam@netfilter.org,
	netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
	stable@vger.kernel.org
Subject: Re: [PATCH] netfilter: conntrack_amanda: fix port value truncation
Message-ID: <ap520Gf4XawDWeaX@strlen.de>
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Aamir Ahmed <elb12345@hotmail.co.uk> wrote:
> amanda_help() uses simple_strtoul() to parse the port number from
> Amanda CONNECT replies, passing the result directly through htons()
> into a __be16.  simple_strtoul() returns unsigned long, so values
> above 65535 are silently truncated by the implicit conversion to u16
> inside htons().
> 
> The existing check "port == 0 || len > 5" is insufficient: it
> catches values that truncate to zero (e.g. 65536) and strings longer
> than 5 digits, but misses values 65537-99999 whose u16 truncation is
> non-zero.  For example, port 65537 becomes port 1, creating a
> conntrack expectation for an unintended port.
> 
> Parse into an unsigned long and explicitly reject values above 65535
> before the htons() conversion, mirroring the pattern used by the FTP
> helper's get_port() and the recent IPVS FTP fix (commit
> e625a9477d12).

Is amanda still a thing?  Maybe time to retire this helper?