[PATCH] fetch: Fix segfault on pull --set-upstream outside a branch.

[PATCH] fetch: Fix segfault on pull --set-upstream outside a branch.

[Clemens Fruhwirth]

branch_get("HEAD") can return NULL, when we are outside a branch and
the user calls pull --set-upstream. Catch this case and warn the user
to avoid a segfault.

Signed-off-by: Clemens Fruhwirth <clemens@endorphin.org>
---
 builtin/fetch.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/builtin/fetch.c b/builtin/fetch.c
index 9191620e50..1097235b90 100644
--- a/builtin/fetch.c
+++ b/builtin/fetch.c
@@ -1602,6 +1602,10 @@ static int do_fetch(struct transport *transport,
 		struct ref *rm;
 		struct ref *source_ref = NULL;
 
+		if (!branch) {
+			warning(_("no branch detected to use --set-upstream with."));
+			goto skip;
+		}
 		/*
 		 * We're setting the upstream configuration for the
 		 * current branch. The relevant upstream is the
-- 
2.31.1

Re: [PATCH] fetch: Fix segfault on pull --set-upstream outside a branch.

[Junio C Hamano]

Clemens Fruhwirth <clemens@endorphin.org> writes:

> branch_get("HEAD") can return NULL, when we are outside a branch and
> the user calls pull --set-upstream. Catch this case and warn the user
> to avoid a segfault.

Nit.  What do you mean by "outside a branch"?  If you mean "when the
HEAD is detached", please say so, and use the same terminology in
your warning message.

Thanks.

>
> Signed-off-by: Clemens Fruhwirth <clemens@endorphin.org>
> ---
>  builtin/fetch.c | 4 ++++
>  1 file changed, 4 insertions(+)
>
> diff --git a/builtin/fetch.c b/builtin/fetch.c
> index 9191620e50..1097235b90 100644
> --- a/builtin/fetch.c
> +++ b/builtin/fetch.c
> @@ -1602,6 +1602,10 @@ static int do_fetch(struct transport *transport,
>  		struct ref *rm;
>  		struct ref *source_ref = NULL;
>  
> +		if (!branch) {
> +			warning(_("no branch detected to use --set-upstream with."));
> +			goto skip;
> +		}
>  		/*
>  		 * We're setting the upstream configuration for the
>  		 * current branch. The relevant upstream is the

Re: [PATCH] fetch: Fix segfault on pull --set-upstream outside a branch.

[Eric Sunshine]

On Tue, Jul 6, 2021 at 1:57 PM Junio C Hamano <gitster@pobox.com> wrote:
> Clemens Fruhwirth <clemens@endorphin.org> writes:
>
> > branch_get("HEAD") can return NULL, when we are outside a branch and
> > the user calls pull --set-upstream. Catch this case and warn the user
> > to avoid a segfault.
>
> Nit.  What do you mean by "outside a branch"?  If you mean "when the
> HEAD is detached", please say so, and use the same terminology in
> your warning message.

Also, adding a new test, probably to `t/t5553-set-upstream.sh`, would
be welcome. The test can likely be as simple as ensuring that the
command does not crash, and perhaps check that the outcome was as
expected.

Re: [PATCH] fetch: Fix segfault on pull --set-upstream outside a branch.

[Junio C Hamano]

Junio C Hamano <gitster@pobox.com> writes:

> Nit.  What do you mean by "outside a branch"?  If you mean "when the
> HEAD is detached", please say so, and use the same terminology in
> your warning message.

Here is what I queued for today's integration run.  Eric's
suggestion to add a simple test is a good idea, too.

Thanks.

-- >8 --
From: Clemens Fruhwirth <clemens@endorphin.org>
Date: Tue, 6 Jul 2021 18:22:38 +0200
Subject: [PATCH] fetch: fix segfault on pull --set-upstream while on a detached HEAD

branch_get("HEAD") can return NULL, when HEAD is detached, and cause
the code to segfault when the user calls "pull --set-upstream".

Catch this case and warn the user to avoid a segfault.

Signed-off-by: Clemens Fruhwirth <clemens@endorphin.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 builtin/fetch.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/builtin/fetch.c b/builtin/fetch.c
index dfde96a435..0a11430df4 100644
--- a/builtin/fetch.c
+++ b/builtin/fetch.c
@@ -1602,6 +1602,10 @@ static int do_fetch(struct transport *transport,
 		struct ref *rm;
 		struct ref *source_ref = NULL;
 
+		if (!branch) {
+			warning(_("no branch detected to use --set-upstream with."));
+			goto skip;
+		}
 		/*
 		 * We're setting the upstream configuration for the
 		 * current branch. The relevant upstream is the
-- 
2.32.0-288-g654beb0eda

Re: [PATCH] fetch: Fix segfault on pull --set-upstream outside a branch.

[Junio C Hamano]

Junio C Hamano <gitster@pobox.com> writes:

> Junio C Hamano <gitster@pobox.com> writes:
>
>> Nit.  What do you mean by "outside a branch"?  If you mean "when the
>> HEAD is detached", please say so, and use the same terminology in
>> your warning message.
>
> Here is what I queued for today's integration run.  Eric's
> suggestion to add a simple test is a good idea, too.

Oops, wrong patch.
-- >8 --
From: Clemens Fruhwirth <clemens@endorphin.org>
Date: Tue, 6 Jul 2021 18:22:38 +0200
Subject: [PATCH] fetch: fix segfault on --set-upstream while on a detached HEAD

branch_get("HEAD") can return NULL, when HEAD is detached, and cause
the code to segfault when the user calls "git pull --set-upstream".

Catch this case and warn the user to avoid a segfault.

Signed-off-by: Clemens Fruhwirth <clemens@endorphin.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 builtin/fetch.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/builtin/fetch.c b/builtin/fetch.c
index dfde96a435..4efdd28396 100644
--- a/builtin/fetch.c
+++ b/builtin/fetch.c
@@ -1602,6 +1602,10 @@ static int do_fetch(struct transport *transport,
 		struct ref *rm;
 		struct ref *source_ref = NULL;
 
+		if (!branch) {
+			warning(_("not on a branch to use --set-upstream with"));
+			goto skip;
+		}
 		/*
 		 * We're setting the upstream configuration for the
 		 * current branch. The relevant upstream is the
-- 
2.32.0-288-g654beb0eda