From: Florian Westphal <fw@strlen.de>
To: "Kito Xu (veritas501)" <hxzene@gmail.com>
Cc: pablo@netfilter.org, phil@nwl.cc, davem@davemloft.net,
edumazet@google.com, kuba@kernel.org, pabeni@redhat.com,
horms@kernel.org, jengelh@medozas.de, kaber@trash.net,
netfilter-devel@vger.kernel.org, coreteam@netfilter.org,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] netfilter: xt_realm: fix null-ptr-deref in realm_mt()
Date: Wed, 15 Apr 2026 11:02:15 +0200 [thread overview]
Message-ID: <ad9UF5Cr12YGJnbi@strlen.de> (raw)
In-Reply-To: <20260415034343.107920-1-hxzene@gmail.com>
Kito Xu (veritas501) <hxzene@gmail.com> wrote:
> realm_mt() unconditionally dereferences skb_dst(skb) without a NULL
> check. The xt_realm match registers with .family = NFPROTO_UNSPEC,
> making it available to all netfilter protocol families. Through the
> nftables compat layer (nft_compat), an unprivileged user inside a
> user/net namespace can load this match into a bridge-family chain.
I do not think this bug is related to nft_compat.
You can also use ebtables setsockopt api to request xt_realm, no?
> Fixes: ab4f21e6fb1c ("netfilter: xtables: use NFPROTO_UNSPEC in more extensions")
Looks correct. Alternatively we could revert the xt_realm.c change.
But I don't have a strong opinion here, patch looks correct.
next prev parent reply other threads:[~2026-04-15 9:02 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-04-15 3:43 [PATCH] netfilter: xt_realm: fix null-ptr-deref in realm_mt() Kito Xu (veritas501)
2026-04-15 9:02 ` Florian Westphal [this message]
2026-04-15 9:27 ` Pablo Neira Ayuso
2026-04-15 9:44 ` Florian Westphal
2026-04-15 16:21 ` Pablo Neira Ayuso
2026-04-15 9:44 ` Pablo Neira Ayuso
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=ad9UF5Cr12YGJnbi@strlen.de \
--to=fw@strlen.de \
--cc=coreteam@netfilter.org \
--cc=davem@davemloft.net \
--cc=edumazet@google.com \
--cc=horms@kernel.org \
--cc=hxzene@gmail.com \
--cc=jengelh@medozas.de \
--cc=kaber@trash.net \
--cc=kuba@kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=netdev@vger.kernel.org \
--cc=netfilter-devel@vger.kernel.org \
--cc=pabeni@redhat.com \
--cc=pablo@netfilter.org \
--cc=phil@nwl.cc \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox