From: Jakub Kicinski <kuba@kernel.org>
To: Breno Leitao <leitao@debian.org>
Cc: David Laight <david.laight.linux@gmail.com>,
David Ahern <dsahern@kernel.org>,
Ido Schimmel <idosch@nvidia.com>,
"David S. Miller" <davem@davemloft.net>,
Eric Dumazet <edumazet@google.com>,
Paolo Abeni <pabeni@redhat.com>, Simon Horman <horms@kernel.org>,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
kernel-team@meta.com, stable@vger.kernel.org,
Stanislav Fomichev <sdf@fomichev.me>
Subject: Re: [PATCH net 1/2] ipv4: mcast: getsockopt: do not overwrite past optlen
Date: Tue, 11 Aug 2026 08:15:43 -0700 [thread overview]
Message-ID: <20260811081543.26d18828@kernel.org> (raw)
In-Reply-To: <ansQ8gHcKdS_Q_ji@gmail.com>
On Tue, 11 Aug 2026 05:19:17 -0700 Breno Leitao wrote:
> So my question to you: can you point me to actual software that
> passes a "small" optlen and expects the kernel to write past it? That
> would help to decide about the two options above.
If you are very confident that no such SW exists - we can try to queue
this up for -next. (TBH I'm not, mcast specifically may be full of
strange one off manually written user space (as opposed to common libraries)).
If we decide to change the behavior- we will probably have to wait
until this makes it to an LTS release + some time for people to deploy.
It can't be a fix.
So practically speaking it may be more expedient to add some hacks to
cater to this case in the conversion, and then remove the hack. That'd
be easier to revert if someone pipes up later that we broke their SW.
next prev parent reply other threads:[~2026-08-11 15:15 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-08-06 9:41 [PATCH net 0/2] net: mcast: do not write past optlen in the source filter getsockopt Breno Leitao
2026-08-06 9:42 ` [PATCH net 1/2] ipv4: mcast: getsockopt: do not overwrite past optlen Breno Leitao
2026-08-07 16:44 ` David Laight
2026-08-10 12:48 ` Breno Leitao
2026-08-10 21:21 ` David Laight
2026-08-11 12:19 ` Breno Leitao
2026-08-11 15:15 ` Jakub Kicinski [this message]
2026-08-11 17:51 ` David Laight
2026-08-06 9:42 ` [PATCH net 2/2] ipv6: mcast: do not write past optlen in the source filter getsockopt Breno Leitao
2026-08-07 16:44 ` David Laight
2026-08-07 14:38 ` [PATCH net 0/2] net: " Simon Horman
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