Re: [PATCH] receive-pack: fix crash on out-of-namespace symref

From: Junio C Hamano <gitster@pobox.com>
Date: Dec 28, 2025, 14:57 UTC
Message-ID: <xmqqfr8uk61i.fsf@gitster.g>
In-Reply-To: <pull.2144.git.git.1766850014289.gitgitgadget@gmail.com>

"Troels Thomsen via GitGitGadget" <gitgitgadget@gmail.com> writes:

Show 17 quoted lines

> From: Troels Thomsen <troels@thomsen.io>
>
> `check_aliased_update_internal()` detects when a symbolic ref and its
> target are being updated in the same push. It does this by building a
> list of ref names without the optional namespace prefix. When a symbolic
> ref within a namespace points to a ref outside the namespace,
> `strip_namespace()` returns NULL which leads to a segfault.
>
> A NULL check preventing this particular issue was repurposed in
> ded8393610. Rather than reintroducing it, we can instead build a list of
> fully qualified ref names. This prevents the crash, preserves the
> consistency check from da3efdb17b, and allows updates to all symbolic
> refs.
>
> Signed-off-by: Troels Thomsen <troels@thomsen.io>
> ---
>     receive-pack: fix crash on out-of-namespace symref

Fixing crash is certainly a good thing, but when the namespace is segregated and receive-pack wants to get updates only within the given namespace, would presence of such a cross namespace symref cause updates outside the namespace through the symref, defeating the point of setting up a namespace in the first place?

I am not objecting to the new behaviour, but am not sure if it is a sensible one. You _might_ be able to argue that an attempt to update underlying refs outside the namespace through such a symbolic ref should result in an error (i.e., a fix to the current crashing behaviour is to die in a controlled way).

Thoughts?