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From: Johannes Schindelin <Johannes.Schindelin@gmx.de>
To: Jinoh Kang <luke1337@theori.io>
Cc: Junio C Hamano <junio@pobox.com>, git@vger.kernel.org
Subject: Re: [PATCH v4] diff: make diff_free_filespec_data accept NULL
Date: Tue, 10 Nov 2020 16:38:39 +0100 (CET)	[thread overview]
Message-ID: <nycvar.QRO.7.76.6.2011101638080.18437@tvgsbejvaqbjf.bet> (raw)
In-Reply-To: <137f0fc1-fbd9-a62c-bd52-cffd26c364bf@theori.io>

Hi Jinoh,

On Tue, 10 Nov 2020, Jinoh Kang wrote:

> Today, diff_free_filespec_data crashes when passed a NULL pointer.
> Commit 3aef54e8b8 ("diff: munmap() file contents before running external
> diff") introduced calls to diff_free_filespec_data in run_external_diff,
> which may pass NULL pointers.
>
> Git uses NULL filespecs to indicate unmerged files when merge conflict
> resolution is in progress.  Fortunately, other code paths bail out early
> even before NULL can reach diff_free_filespec_data(); however, difftool
> is expected to do a full-blown diff anyway regardless of conflict
> status.
>
> Fix this and prevent any similar bugs in the future by making
> `diff_free_filespec_data(NULL)` a no-op.
>
> Also, add a test case that confirms that running difftool --cached with
> unmerged files does not SIGSEGV.
>
> Signed-off-by: Jinoh Kang <luke1337@theori.io>
> ---
>  diff.c              |  3 +++
>  t/t7800-difftool.sh | 23 +++++++++++++++++++++++
>  2 files changed, 26 insertions(+)
>
> diff --git a/diff.c b/diff.c
> index d24f47df99..ace4a1d387 100644
> --- a/diff.c
> +++ b/diff.c
> @@ -4115,6 +4115,9 @@ void diff_free_filespec_blob(struct diff_filespec *s)
>
>  void diff_free_filespec_data(struct diff_filespec *s)
>  {
> +	if (!s)
> +		return;
> +

I had suggested an improvement for this hunk as well as for the test case.
Fell through the cracks?

Ciao,
Dscho

>  	diff_free_filespec_blob(s);
>  	FREE_AND_NULL(s->cnt_data);
>  }
> diff --git a/t/t7800-difftool.sh b/t/t7800-difftool.sh
> index 524f30f7dc..e9391abb54 100755
> --- a/t/t7800-difftool.sh
> +++ b/t/t7800-difftool.sh
> @@ -728,6 +728,29 @@ test_expect_success 'add -N and difftool -d' '
>  	git difftool --dir-diff --extcmd ls
>  '
>
> +test_expect_success 'difftool --cached with unmerged files' '
> +	test_when_finished git reset --hard &&
> +	echo base >file &&
> +	git add file &&
> +	git commit -m base &&
> +	git checkout -B conflict-a &&
> +	git checkout -B conflict-b &&
> +	git checkout conflict-a &&
> +	echo conflict-a >>file &&
> +	git add file &&
> +	git commit -m conflict-a &&
> +	git checkout conflict-b &&
> +	echo conflict-b >>file &&
> +	git add file &&
> +	git commit -m conflict-b &&
> +	git checkout master &&
> +	git merge conflict-a &&
> +	test_must_fail git merge conflict-b &&
> +	: >expect &&
> +	git difftool --cached --no-prompt >actual &&
> +	test_cmp expect actual
> +'
> +
>  test_expect_success 'outside worktree' '
>  	echo 1 >1 &&
>  	echo 2 >2 &&
> --
> 2.26.2
>

  reply	other threads:[~2020-11-10 15:38 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <aeb24944-17af-cf53-93f4-e727f9fe9988@theori.io>
     [not found] ` <xmqq4km4lppy.fsf@gitster.c.googlers.com>
2020-11-06 17:02   ` [PATCH v2] diff: handle NULL filespecs in run_external_diff Jinoh Kang
2020-11-06 17:14     ` [PATCH v3] diff: make diff_free_filespec_data accept NULL Jinoh Kang
2020-11-10 12:08       ` Johannes Schindelin
2020-11-10 13:16         ` Jinoh Kang
2020-11-10 14:21         ` Jinoh Kang
2020-11-10 17:02         ` Junio C Hamano
2020-11-10 14:06       ` [PATCH v4] " Jinoh Kang
2020-11-10 15:38         ` Johannes Schindelin [this message]
2020-11-11 12:30           ` Jinoh Kang
2020-11-11 16:28             ` Johannes Schindelin
2020-11-10 19:41         ` Junio C Hamano
2020-11-11 12:15         ` [PATCH v5] " Jinoh Kang
2020-11-11 16:27           ` Johannes Schindelin
2020-11-11 19:18             ` Junio C Hamano
2020-11-06 19:18     ` [PATCH v2] diff: handle NULL filespecs in run_external_diff Junio C Hamano

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