diff mbox series

[v2] trace2: prevent segfault on config collection where no value specified

Message ID pull.1814.v2.git.1736494100622.gitgitgadget@gmail.com (mailing list archive)
State New
Headers show
Series [v2] trace2: prevent segfault on config collection where no value specified | expand

Commit Message

Adam Murray Jan. 10, 2025, 7:28 a.m. UTC
From: Adam Murray <ad@canva.com>

When TRACE2 analytics is enabled, a git config option that has no value
causes a segfault.

Steps to Reproduce
GIT_TRACE2=true GIT_TRACE2_CONFIG_PARAMS=status.*
git -c status.relativePaths version
Expected Result
git version 2.46.0
Actual Result
zsh: segmentation fault GIT_TRACE2=true

This adds checks to prevent the segfault and instead return
an empty value.

Signed-off-by: Adam Murray <ad@canva.com>
---
    trace2: prevent segfault on config collection where no value specified
    
    cc: Jeff King peff@peff.net

Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-1814%2Fad-murray%2Ffix-trace2-segfault-v2
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-1814/ad-murray/fix-trace2-segfault-v2
Pull-Request: https://github.com/gitgitgadget/git/pull/1814

Range-diff vs v1:

 1:  24ba9db7aa1 ! 1:  fd7bed52dda trace2: prevent segfault on config collection where no value specified
     @@ Commit message
          Actual Result
          zsh: segmentation fault GIT_TRACE2=true
      
     -    This adds a null check to prevent the segfault and instead return
     -    the "empty config value" error.
     +    This adds checks to prevent the segfault and instead return
     +    an empty value.
      
          Signed-off-by: Adam Murray <ad@canva.com>
      
     @@ t/t0210-trace2-normal.sh: test_expect_success 'bug messages followed by BUG() ar
      
       ## trace2.c ##
      @@ trace2.c: void trace2_def_param_fl(const char *file, int line, const char *param,
     - 	int j;
     - 	const char *redacted;
     - 
     --	if (!trace2_enabled)
     -+	if (!trace2_enabled || !value)
     + 	if (!trace2_enabled)
       		return;
       
     - 	redacted = redact_arg(value);
     +-	redacted = redact_arg(value);
     ++	redacted = value ? redact_arg(value): NULL;
     + 
     + 	for_each_wanted_builtin (j, tgt_j)
     + 		if (tgt_j->pfn_param_fl)
     +
     + ## trace2/tr2_tgt_event.c ##
     +@@ trace2/tr2_tgt_event.c: static void fn_param_fl(const char *file, int line, const char *param,
     + 	event_fmt_prepare(event_name, file, line, NULL, &jw);
     + 	jw_object_string(&jw, "scope", scope_name);
     + 	jw_object_string(&jw, "param", param);
     +-	jw_object_string(&jw, "value", value);
     ++	if (value)
     ++		jw_object_string(&jw, "value", value);
     + 	jw_end(&jw);
     + 
     + 	tr2_dst_write_line(&tr2dst_event, &jw.json);
     +
     + ## trace2/tr2_tgt_normal.c ##
     +@@ trace2/tr2_tgt_normal.c: static void fn_param_fl(const char *file, int line, const char *param,
     + 	enum config_scope scope = kvi->scope;
     + 	const char *scope_name = config_scope_name(scope);
     + 
     +-	strbuf_addf(&buf_payload, "def_param scope:%s %s=%s", scope_name, param,
     +-		    value);
     ++	strbuf_addf(&buf_payload, "def_param scope:%s %s", scope_name, param);
     ++	if (value)
     ++		strbuf_addf(&buf_payload, "=%s", value);
     + 	normal_io_write_fl(file, line, &buf_payload);
     + 	strbuf_release(&buf_payload);
     + }
     +
     + ## trace2/tr2_tgt_perf.c ##
     +@@ trace2/tr2_tgt_perf.c: static void fn_param_fl(const char *file, int line, const char *param,
     + 	struct strbuf scope_payload = STRBUF_INIT;
     + 	enum config_scope scope = kvi->scope;
     + 	const char *scope_name = config_scope_name(scope);
     +-
     +-	strbuf_addf(&buf_payload, "%s:%s", param, value);
     ++	strbuf_addstr(&buf_payload, param);
     ++	if (value)
     ++		strbuf_addf(&buf_payload, ":%s", value);
     + 	strbuf_addf(&scope_payload, "%s:%s", "scope", scope_name);
     + 
     + 	perf_io_write_fl(file, line, event_name, NULL, NULL, NULL,


 t/t0210-trace2-normal.sh | 8 ++++++++
 trace2.c                 | 2 +-
 trace2/tr2_tgt_event.c   | 3 ++-
 trace2/tr2_tgt_normal.c  | 5 +++--
 trace2/tr2_tgt_perf.c    | 5 +++--
 5 files changed, 17 insertions(+), 6 deletions(-)


base-commit: 8f8d6eee531b3fa1a8ef14f169b0cb5035f7a772

Comments

Junio C Hamano Jan. 10, 2025, 5:10 p.m. UTC | #1
"Adam Murray via GitGitGadget" <gitgitgadget@gmail.com> writes:

> From: Adam Murray <ad@canva.com>
>
> When TRACE2 analytics is enabled, a git config option that has no value
> causes a segfault.

We often call this "valueless true syntax".  It may techincally
correct to say "has no value", but it is more friendly to readers if
you said "a configuration variable that is set to 'true' with
the valueless true syntax".

> diff --git a/trace2.c b/trace2.c
> index f894532d053..49e7d1db88f 100644
> --- a/trace2.c
> +++ b/trace2.c
> @@ -762,7 +762,7 @@ void trace2_def_param_fl(const char *file, int line, const char *param,
>  	if (!trace2_enabled)
>  		return;
>  
> -	redacted = redact_arg(value);
> +	redacted = value ? redact_arg(value): NULL;
>  
>  	for_each_wanted_builtin (j, tgt_j)
>  		if (tgt_j->pfn_param_fl)
> diff --git a/trace2/tr2_tgt_event.c b/trace2/tr2_tgt_event.c
> index 45b0850a5ec..8e09485c83c 100644
> --- a/trace2/tr2_tgt_event.c
> +++ b/trace2/tr2_tgt_event.c
> @@ -491,7 +491,8 @@ static void fn_param_fl(const char *file, int line, const char *param,
>  	event_fmt_prepare(event_name, file, line, NULL, &jw);
>  	jw_object_string(&jw, "scope", scope_name);
>  	jw_object_string(&jw, "param", param);
> -	jw_object_string(&jw, "value", value);
> +	if (value)
> +		jw_object_string(&jw, "value", value);
>  	jw_end(&jw);

OK, so for "valueless true", we do not get the "value" element in
the json output, which makes sense.  Don't we have documentation
that explains what each element in the output means and when they
are given?  Shouldn't we update it?

> -	strbuf_addf(&buf_payload, "def_param scope:%s %s=%s", scope_name, param,
> -		    value);
> +	strbuf_addf(&buf_payload, "def_param scope:%s %s", scope_name, param);
> +	if (value)
> +		strbuf_addf(&buf_payload, "=%s", value);

OK.

The input did not spell the "=value" part and said "[section] key"
to mean that section.key is true, so we report that without "=value"
part.  This also makes sense.

> diff --git a/trace2/tr2_tgt_perf.c b/trace2/tr2_tgt_perf.c
> index a6f9a8a193e..19ae7433ef8 100644
> --- a/trace2/tr2_tgt_perf.c
> +++ b/trace2/tr2_tgt_perf.c
> @@ -446,8 +446,9 @@ static void fn_param_fl(const char *file, int line, const char *param,
>  	struct strbuf scope_payload = STRBUF_INIT;
>  	enum config_scope scope = kvi->scope;
>  	const char *scope_name = config_scope_name(scope);
> -
> -	strbuf_addf(&buf_payload, "%s:%s", param, value);
> +	strbuf_addstr(&buf_payload, param);
> +	if (value)
> +		strbuf_addf(&buf_payload, ":%s", value);

I am not versed well enough in tgt-parf output format to tell if
this makes sense.  We'd need somebody else to review this part.

Thanks.
diff mbox series

Patch

diff --git a/t/t0210-trace2-normal.sh b/t/t0210-trace2-normal.sh
index b9adc94aab4..4047ab562a4 100755
--- a/t/t0210-trace2-normal.sh
+++ b/t/t0210-trace2-normal.sh
@@ -244,6 +244,14 @@  test_expect_success 'bug messages followed by BUG() are written to trace2' '
 	test_cmp expect actual
 '
 
+test_expect_success 'empty configuration values are handled' '
+  test_when_finished "rm trace2.normal actual expect" &&
+  echo >expect &&
+  GIT_TRACE2="$(pwd)/trace2.normal"  GIT_TRACE2_CONFIG_PARAMS=foo.empty \
+	  git -c foo.empty config foo.empty >actual &&
+	test_cmp expect actual
+'
+
 sane_unset GIT_TRACE2_BRIEF
 
 # Now test without environment variables and get all Trace2 settings
diff --git a/trace2.c b/trace2.c
index f894532d053..49e7d1db88f 100644
--- a/trace2.c
+++ b/trace2.c
@@ -762,7 +762,7 @@  void trace2_def_param_fl(const char *file, int line, const char *param,
 	if (!trace2_enabled)
 		return;
 
-	redacted = redact_arg(value);
+	redacted = value ? redact_arg(value): NULL;
 
 	for_each_wanted_builtin (j, tgt_j)
 		if (tgt_j->pfn_param_fl)
diff --git a/trace2/tr2_tgt_event.c b/trace2/tr2_tgt_event.c
index 45b0850a5ec..8e09485c83c 100644
--- a/trace2/tr2_tgt_event.c
+++ b/trace2/tr2_tgt_event.c
@@ -491,7 +491,8 @@  static void fn_param_fl(const char *file, int line, const char *param,
 	event_fmt_prepare(event_name, file, line, NULL, &jw);
 	jw_object_string(&jw, "scope", scope_name);
 	jw_object_string(&jw, "param", param);
-	jw_object_string(&jw, "value", value);
+	if (value)
+		jw_object_string(&jw, "value", value);
 	jw_end(&jw);
 
 	tr2_dst_write_line(&tr2dst_event, &jw.json);
diff --git a/trace2/tr2_tgt_normal.c b/trace2/tr2_tgt_normal.c
index baef48aa698..924736ab360 100644
--- a/trace2/tr2_tgt_normal.c
+++ b/trace2/tr2_tgt_normal.c
@@ -307,8 +307,9 @@  static void fn_param_fl(const char *file, int line, const char *param,
 	enum config_scope scope = kvi->scope;
 	const char *scope_name = config_scope_name(scope);
 
-	strbuf_addf(&buf_payload, "def_param scope:%s %s=%s", scope_name, param,
-		    value);
+	strbuf_addf(&buf_payload, "def_param scope:%s %s", scope_name, param);
+	if (value)
+		strbuf_addf(&buf_payload, "=%s", value);
 	normal_io_write_fl(file, line, &buf_payload);
 	strbuf_release(&buf_payload);
 }
diff --git a/trace2/tr2_tgt_perf.c b/trace2/tr2_tgt_perf.c
index a6f9a8a193e..19ae7433ef8 100644
--- a/trace2/tr2_tgt_perf.c
+++ b/trace2/tr2_tgt_perf.c
@@ -446,8 +446,9 @@  static void fn_param_fl(const char *file, int line, const char *param,
 	struct strbuf scope_payload = STRBUF_INIT;
 	enum config_scope scope = kvi->scope;
 	const char *scope_name = config_scope_name(scope);
-
-	strbuf_addf(&buf_payload, "%s:%s", param, value);
+	strbuf_addstr(&buf_payload, param);
+	if (value)
+		strbuf_addf(&buf_payload, ":%s", value);
 	strbuf_addf(&scope_payload, "%s:%s", "scope", scope_name);
 
 	perf_io_write_fl(file, line, event_name, NULL, NULL, NULL,