Bug 2042920

Summary:	Checkout of a custom ref fails with a core dump
Product:	[Fedora] Fedora	Reporter:	Petr Šplíchal <psplicha>
Component:	git	Assignee:	Todd Zullinger <tmz>
Status:	CLOSED ERRATA	QA Contact:	Fedora Extras Quality Assurance <extras-qa>
Severity:	unspecified	Docs Contact:
Priority:	unspecified
Version:	rawhide	CC:	amahdal, besser82, chrisw, johannes, opohorel, pstodulk, sebastian.kisela, tmz
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Hardware:	Unspecified
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Fixed In Version:	git-2.35.0-1.fc36	Doc Type:	If docs needed, set a value
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Last Closed:	2022-01-25 02:01:20 UTC	Type:	Bug
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oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
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Description Petr Šplíchal 2022-01-20 11:13:02 UTC

Description of problem:
Checking out a manually created ref for the second time
results in a core dump.

Version-Release number of selected component (if applicable):
git-2.35.0-0.1.rc1.fc36.x86_64

Steps to Reproduce:
git clone https://github.com/psss/fmf /tmp/fmf
cd /tmp/fmf
cp .git/refs/remotes/origin/HEAD .git/refs/heads/__DEFAULT__
git checkout -f __DEFAULT__
git checkout -f __DEFAULT__

Actual results:
Switched to branch '__DEFAULT__'
BUG: builtin/checkout.c:1098: should be able to skip past 'refs/heads/' in 'refs/remotes/origin/master'!
Aborted (core dumped)

Expected results:
Checkout works fine second time as well.

Additional info:
Works fine with git-2.34.1-1.fc35.x86_64.

Related fmf issue:
https://github.com/psss/fmf/issues/149

Comment 1 Todd Zullinger 2022-01-20 16:56:09 UTC

Thanks for the report Petr!

This looks to have originated in upstream 9081a421a6 (checkout: fix "branch info" memory leaks, 2021-11-16).

I sent a message upstream (with you on Cc:): https://lore.kernel.org/git/YemTGQZ97vAPUPY0@pobox.com/

Comment 2 Petr Šplíchal 2022-01-21 10:38:39 UTC

Thanks for looking into this so quickly! According to the upstream
discussion I see we're doing unexpected things by copying the
remote ref to refs/heads.

Would you recommend a better way to easily detect the default
origin branch from a script within a repository where arbitrary
branch is currently checked out?

The use case is roughly this:

    git clone ...
    git checkout -b custom-branch
    ...
    git checkout -f <default-branch>
    git reset --hard origin/<default-branch>

Thanks for any hint!

Comment 3 Fedora Update System 2022-01-25 01:59:14 UTC

FEDORA-2022-a63d9a0b84 has been submitted as an update to Fedora 36. https://bodhi.fedoraproject.org/updates/FEDORA-2022-a63d9a0b84

Comment 4 Fedora Update System 2022-01-25 02:01:20 UTC

FEDORA-2022-a63d9a0b84 has been pushed to the Fedora 36 stable repository.
If problem still persists, please make note of it in this bug report.