Re: [PATCH net v4 1/2] net/rds: keep the connected peer's scope id apart from the bound one

[sashiko-bot@kernel.org]

> rds_connect() has nowhere to keep the scope of a link-local peer, so
> it stores it in rs_bound_scope_id, the scope of the socket's own
> bound address, for rds_bind() to check a later link-local bind
> against.  That field is then also what a send without a destination
> uses as the request's scope, what getpeername() and recvmsg() report
> as the peer's scope, and what a later bind() overwrites:
> rds_add_bound() stores the bound address's scope unconditionally,
> which for a non-link-local address is 0.
> 
> So after connect(fe80::x%ifA) followed by bind(global), a send() with
> no destination asks for fe80::x with scope 0.  rds_conn_lookup() keys
> on the interface, so that finds or creates a connection with c_dev_if
> 0, which the TCP transport then tries to connect through
> sin6_scope_id 0 and tcp_v6_connect() rejects for a link-local peer:
> the connected socket's data is queued on a connection that can never
> [ ... ]
> observed in the field.
> 
> Fixes: 1e2b44e78eea ("rds: Enable RDS IPv6 support")
> Assisted-by: Claude-Code:claude-fable-5
> Signed-off-by: Allison Henderson <achender@kernel.org>

Sashiko has reviewed this patch and found no issues. It looks great!

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261008031426.1142344-1-achender@kernel.org?part=1