Re: [PATCH] line-log: protect inner strbuf from free

From

Jeff King <peff@peff.net>

Date

Oct 3, 2024, 00:19 UTC

Message-ID

<20241003001945.GA3486271@coredump.intra.peff.net>

In-Reply-To

<20241002235639.GB3455554@coredump.intra.peff.net>

On Wed, Oct 02, 2024 at 07:56:39PM -0400, Jeff King wrote:

> Good catch. Your analysis looks correct, though I had two questions I
> managed to answer myself:
> 
>   1. This seems like an obvious use-after-free problem. Why didn't we
>      catch it sooner? I think the answer is that most uses of the
>      output_prefix callback happen via diff_line_prefix(), which was not
>      broken by 394affd46d. It's only line-log that was affected.
> 
>      Building with ASan and running:
> 
>        ./git log --graph -L :diff_line_prefix:diff.c
> 
>      shows the problem immediately (and that your patch fixes it).
>      Should we include a new test in this patch?

diff --git a/t/t4211-line-log.sh b/t/t4211-line-log.sh
index 02d76dca28..950451cf6a 100755
--- a/t/t4211-line-log.sh
+++ b/t/t4211-line-log.sh
@@ -337,4 +337,32 @@ test_expect_success 'zero-width regex .* matches any function name' '
 	test_cmp expect actual
 '
 
+test_expect_success 'show line-log with graph' '
+	qz_to_tab_space >expect <<-EOF &&
+	* $head_oid Modify func2() in file.c
+	|Z
+	| diff --git a/file.c b/file.c
+	| --- a/file.c
+	| +++ b/file.c
+	| @@ -6,4 +6,4 @@
+	|  int func2()
+	|  {
+	| -    return F2;
+	| +    return F2 + 2;
+	|  }
+	* $root_oid Add func1() and func2() in file.c
+	ZZ
+	  diff --git a/file.c b/file.c
+	  --- /dev/null
+	  +++ b/file.c
+	  @@ -0,0 +6,4 @@
+	  +int func2()
+	  +{
+	  +    return F2;
+	  +}
+	EOF
+	git log --graph --oneline -L:func2:file.c >actual &&
+	test_cmp expect actual
+'
+
 test_done

-Peff