[PATCHES v7 0/2] perf c2c hardening

[PATCHES v7 0/2] perf c2c hardening

[Arnaldo Carvalho de Melo]

Hi,

Fixes for 'perf c2c' found by the sashiko-bot and
Opencode:mimo-v2.5-free AI reviewers, both using Chris Mason's
review-prompts:

Patch 1 fixes three silent failure modes in hpp_list__parse().

Patch 2 fixes a format list leak: when c2c_hists__[re]init() fails
partway through, entries registered via perf_hpp_list__column_register()
and perf_hpp_list__register_sort_field() are left on the hpp_list.

Please consider merging,

- Arnaldo

Changes since v6:

- c2c_hists__reinit() has the same leak: it clears the list then calls
  hpp_list__parse(), which can register formats before failing, and
  neither the function nor its callers clean up on failure.  Add the same
  cleanup-on-failure pattern to close this gap.

Changes since v5:

- The second v5 patch didn't got thru, resending the same contents as v5.

Changes since v4:

- Replace %m with str_error_r(-ret) as suggested by Sashiko.

Changes since v3:

 - Use 'goto out' to break out from both the switch and the for loop in
   __hpp_list__parse() as noticed by sashiko.

Changes since v2:

  - Added the string.h and stdlib.h missing headers.
  - Addressed sashiko comment on PARSE_LIST, turning it into a function
    and handling all errors returned from _fn().

Changes since v1:

  - Addressed sashiko-bot [Medium] finding: the early exits added by v1
    skip perf_hpp__setup_output_field().
  - Dismissed sashiko-bot [Low] finding (missing string.h/stdlib.h):
    strdup() and free() were already used in this function before this
    patch; string2.h (included at the top of the file) pulls in string.h.
    No new library calls were introduced.
  - Subject updated to reflect the additional caller fixes.

This series was developed with AI assistance (Claude:Sonnet 4.6,
Opencode:mimo-v2.5-free).


Arnaldo Carvalho de Melo (2):
  perf c2c: Fix error masking, OOM, and unchecked caller errors in
    hpp_list__parse()
  perf c2c: Clean up registered formats on c2c_hists__init() and
    c2c_hists__reinit() failure

 tools/perf/builtin-c2c.c | 105 +++++++++++++++++++++++++++++----------
 tools/perf/util/sort.c   |  38 ++++++++------
 2 files changed, 100 insertions(+), 43 deletions(-)

-- 
2.55.0

[PATCH 1/2] perf c2c: Fix error masking, OOM, and unchecked caller errors in hpp_list__parse()

[Arnaldo Carvalho de Melo]

From: Arnaldo Carvalho de Melo <acme@redhat.com>

hpp_list__parse() has three bugs:

1. The PARSE_LIST macro resets ret = 0 at the start of each invocation,
   so an error from output parsing is silently overwritten when the sort
   parsing block runs.  The function returns success with partially
   initialized state.

2. When the caller passes a non-NULL output_ or sort_ string, but
   strdup() returns NULL due to OOM, NULL is passed to PARSE_LIST which
   treats it as empty input (the "if (!_list) break" branch).  No error
   is returned.

3. When the called _fn function fails and returns something other than
   -ESRCH or -EINVAL (-ENOMEM, for instance) it was not bailing out of
   the strtok loop.

Fix them by checking strdup() return values before proceeding and adding
a cleanup label so that ret from each PARSE_LIST call is checked before
the next runs, preserving the first error.

The early exits now skip perf_hpp__setup_output_field(), which means
c2c_hists__reinit() can return a non-zero value in cases that previously
always succeeded silently.  Both callers discarded its return:
resort_cl_cb() continued into hists__collapse_resort() on a broken list,
and perf_c2c__report() proceeded with uninitialised hists.  Fix the full
chain: check and propagate the error in resort_cl_cb() -- hists__iterate_cb()
already stops iteration and returns the callback error -- and check both
c2c_hists__reinit() and hists__iterate_cb() in perf_c2c__report().

Also turn PARSE_LIST into a function, using a switch to catch other
errors, converting the called functions to return an appropriate errno
instead of -1 on failure.

Fixes: 2d388bd0c9d3 ("perf c2c report: Add stdio output support")
Reported-by: sashiko-bot <sashiko-bot@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Assisted-by: Claude:claude-sonnet-4.6
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/builtin-c2c.c | 85 ++++++++++++++++++++++++++++------------
 tools/perf/util/sort.c   | 38 ++++++++++--------
 2 files changed, 82 insertions(+), 41 deletions(-)

diff --git a/tools/perf/builtin-c2c.c b/tools/perf/builtin-c2c.c
index c9584dbedf77afe8..160b82694d391c50 100644
--- a/tools/perf/builtin-c2c.c
+++ b/tools/perf/builtin-c2c.c
@@ -12,11 +12,14 @@
  */
 #include <errno.h>
 #include <inttypes.h>
+#include <stdlib.h>
+#include <string.h>
 
 #include <asm/bug.h>
 #include <linux/compiler.h>
 #include <linux/err.h>
 #include <linux/kernel.h>
+#include <linux/string.h>
 #include <linux/stringify.h>
 #include <linux/zalloc.h>
 #include <sys/param.h>
@@ -2063,26 +2066,38 @@ static int c2c_hists__init_sort(struct perf_hpp_list *hpp_list, char *name, stru
 	return 0;
 }
 
-#define PARSE_LIST(_list, _fn)							\
-	do {									\
-		char *tmp, *tok;						\
-		ret = 0;							\
-										\
-		if (!_list)							\
-			break;							\
-										\
-		for (tok = strtok_r((char *)_list, ", ", &tmp);			\
-				tok; tok = strtok_r(NULL, ", ", &tmp)) {	\
-			ret = _fn(hpp_list, tok, env);				\
-			if (ret == -EINVAL) {					\
-				pr_err("Invalid --fields key: `%s'", tok);	\
-				break;						\
-			} else if (ret == -ESRCH) {				\
-				pr_err("Unknown --fields key: `%s'", tok);	\
-				break;						\
-			}							\
-		}								\
-	} while (0)
+static int __hpp_list__parse(struct perf_hpp_list *hpp_list, char *_list, struct perf_env *env,
+			     int (*_fn)(struct perf_hpp_list *hpp_list, char *name, struct perf_env *env))
+{
+	char *tmp, *tok;
+	int ret = 0;
+
+	if (!_list)
+		return 0;
+
+	for (tok = strtok_r(_list, ", ", &tmp); tok; tok = strtok_r(NULL, ", ", &tmp)) {
+		ret = _fn(hpp_list, tok, env);
+		switch (ret) {
+		case 0:
+			continue;
+		case -EINVAL:
+			pr_err("Invalid --fields key: `%s'", tok);
+			goto out;
+		case -ESRCH:
+			pr_err("Unknown --fields key: `%s'", tok);
+			goto out;
+		default: {
+			char buf[STRERR_BUFSIZE];
+
+			pr_err("%s for --fields key: `%s'",
+			       str_error_r(-ret, buf, sizeof(buf)), tok);
+			goto out;
+		}
+		}
+	}
+out:
+	return ret;
+}
 
 static int hpp_list__parse(struct perf_hpp_list *hpp_list,
 			   const char *output_,
@@ -2093,8 +2108,18 @@ static int hpp_list__parse(struct perf_hpp_list *hpp_list,
 	char *sort   = sort_   ? strdup(sort_) : NULL;
 	int ret;
 
-	PARSE_LIST(output, c2c_hists__init_output);
-	PARSE_LIST(sort,   c2c_hists__init_sort);
+	/* strdup() returns NULL on OOM, don't silently treat as empty */
+	if ((output_ && !output) || (sort_ && !sort)) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	ret = __hpp_list__parse(hpp_list, output, env, c2c_hists__init_output);
+	if (ret)
+		goto out;
+	ret = __hpp_list__parse(hpp_list, sort, env, c2c_hists__init_sort);
+	if (ret)
+		goto out;
 
 	/* copy sort keys to output fields */
 	perf_hpp__setup_output_field(hpp_list);
@@ -2111,6 +2136,7 @@ static int hpp_list__parse(struct perf_hpp_list *hpp_list,
 	perf_hpp__append_sort_keys(&hists->list);
 #endif
 
+out:
 	free(output);
 	free(sort);
 	return ret;
@@ -2281,6 +2307,7 @@ static int resort_cl_cb(struct hist_entry *he, void *arg)
 	struct c2c_hist_entry *c2c_he;
 	struct c2c_hists *c2c_hists;
 	bool display = he__display(he, &c2c.shared_clines_stats);
+	int ret;
 
 	c2c_he = container_of(he, struct c2c_hist_entry, he);
 	c2c_hists = c2c_he->hists;
@@ -2291,7 +2318,9 @@ static int resort_cl_cb(struct hist_entry *he, void *arg)
 		c2c_he->cacheline_idx = idx++;
 		calc_width(c2c_he);
 
-		c2c_hists__reinit(c2c_hists, c2c.cl_output, c2c.cl_resort, env);
+		ret = c2c_hists__reinit(c2c_hists, c2c.cl_output, c2c.cl_resort, env);
+		if (ret)
+			return ret;
 
 		hists__collapse_resort(&c2c_hists->hists, NULL);
 		hists__output_resort_cb(&c2c_hists->hists, NULL, filter_cb);
@@ -3356,13 +3385,19 @@ static int perf_c2c__report(int argc, const char **argv)
 	else if (c2c.display == DISPLAY_SNP_PEER)
 		sort_str = "tot_peer";
 
-	c2c_hists__reinit(&c2c.hists, output_str, sort_str, perf_session__env(session));
+	err = c2c_hists__reinit(&c2c.hists, output_str, sort_str, perf_session__env(session));
+	if (err) {
+		pr_err("Failed to reinitialize hists\n");
+		goto out_mem2node;
+	}
 
 	ui_progress__init(&prog, c2c.hists.hists.nr_entries, "Sorting...");
 
 	hists__collapse_resort(&c2c.hists.hists, NULL);
 	hists__output_resort_cb(&c2c.hists.hists, &prog, resort_shared_cl_cb);
-	hists__iterate_cb(&c2c.hists.hists, resort_cl_cb, perf_session__env(session));
+	err = hists__iterate_cb(&c2c.hists.hists, resort_cl_cb, perf_session__env(session));
+	if (err)
+		goto out_mem2node;
 
 	ui_progress__finish();
 
diff --git a/tools/perf/util/sort.c b/tools/perf/util/sort.c
index dcf9189786f8aeba..2f59e37089ef06a2 100644
--- a/tools/perf/util/sort.c
+++ b/tools/perf/util/sort.c
@@ -3105,7 +3105,7 @@ static int __sort_dimension__add_hpp_sort(struct sort_dimension *sd,
 	struct hpp_sort_entry *hse = __sort_dimension__alloc_hpp(sd, level);
 
 	if (hse == NULL)
-		return -1;
+		return -ENOMEM;
 
 	perf_hpp_list__register_sort_field(list, &hse->hpp);
 	return 0;
@@ -3118,7 +3118,7 @@ static int __sort_dimension__add_hpp_output(struct sort_dimension *sd,
 	struct hpp_sort_entry *hse = __sort_dimension__alloc_hpp(sd, level);
 
 	if (hse == NULL)
-		return -1;
+		return -ENOMEM;
 
 	perf_hpp_list__column_register(list, &hse->hpp);
 	return 0;
@@ -3742,14 +3742,18 @@ static int __sort_dimension__add(struct sort_dimension *sd,
 				 struct perf_hpp_list *list,
 				 int level)
 {
+	int ret;
+
 	if (sd->taken)
 		return 0;
 
-	if (__sort_dimension__add_hpp_sort(sd, list, level) < 0)
-		return -1;
+	ret = __sort_dimension__add_hpp_sort(sd, list, level);
+	if (ret < 0)
+		return ret;
 
-	if (__sort_dimension__update(sd, list) < 0)
-		return -1;
+	ret = __sort_dimension__update(sd, list);
+	if (ret < 0)
+		return ret;
 
 	sd->taken = 1;
 
@@ -3767,7 +3771,7 @@ static int __hpp_dimension__add(struct hpp_dimension *hd,
 
 	fmt = __hpp_dimension__alloc_hpp(hd, level);
 	if (!fmt)
-		return -1;
+		return -ENOMEM;
 
 	hd->taken = 1;
 	hd->was_taken = 1;
@@ -3779,14 +3783,18 @@ static int __sort_dimension__add_output(struct perf_hpp_list *list,
 					struct sort_dimension *sd,
 					int level)
 {
+	int ret;
+
 	if (sd->taken)
 		return 0;
 
-	if (__sort_dimension__add_hpp_output(sd, list, level) < 0)
-		return -1;
+	ret = __sort_dimension__add_hpp_output(sd, list, level);
+	if (ret < 0)
+		return ret;
 
-	if (__sort_dimension__update(sd, list) < 0)
-		return -1;
+	ret = __sort_dimension__update(sd, list);
+	if (ret < 0)
+		return ret;
 
 	sd->taken = 1;
 	return 0;
@@ -3803,7 +3811,7 @@ static int __hpp_dimension__add_output(struct perf_hpp_list *list,
 
 	fmt = __hpp_dimension__alloc_hpp(hd, level);
 	if (!fmt)
-		return -1;
+		return -ENOMEM;
 
 	hd->taken = 1;
 	perf_hpp_list__column_register(list, fmt);
@@ -3869,8 +3877,7 @@ int sort_dimension__add(struct perf_hpp_list *list, const char *tok,
 				    strlen(tok)))
 			return -EINVAL;
 
-		__sort_dimension__add(sd, list, level);
-		return 0;
+		return __sort_dimension__add(sd, list, level);
 	}
 
 	for (i = 0; i < ARRAY_SIZE(memory_sort_dimensions); i++) {
@@ -3882,8 +3889,7 @@ int sort_dimension__add(struct perf_hpp_list *list, const char *tok,
 		if (sort__mode != SORT_MODE__MEMORY)
 			return -EINVAL;
 
-		__sort_dimension__add(sd, list, level);
-		return 0;
+		return __sort_dimension__add(sd, list, level);
 	}
 
 	for (i = 0; i < ARRAY_SIZE(hpp_sort_dimensions); i++) {
-- 
2.55.0

[PATCH 2/2] perf c2c: Clean up registered formats on c2c_hists__init() and c2c_hists__reinit() failure

[Arnaldo Carvalho de Melo]

From: Arnaldo Carvalho de Melo <acme@redhat.com>

When c2c_hists__init() or c2c_hists__reinit() calls hpp_list__parse()
and it fails partway through, format structures registered via
perf_hpp_list__column_register() and perf_hpp_list__register_sort_field()
are left on the hpp_list.

In c2c_hists__init(), the c2c_he__alloc_hists() caller handles this with
perf_hpp__reset_output_field(), but perf_c2c_report() does not, leaking
the partially registered entries.

In c2c_hists__reinit(), neither perf_c2c_report() nor resort_cl_cb()
clean up on failure.

Fix by adding cleanup inside both functions themselves, so all callers
are protected.

Fixes: 78b275437873 ("perf c2c report: Add sample processing")
Reported-by: sashiko-bot <sashiko-bot@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Assisted-by: Claude:claude-opus-4.6
Assisted-by: Opencode:mimo-v2.5-free
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/builtin-c2c.c | 20 ++++++++++++++++++--
 1 file changed, 18 insertions(+), 2 deletions(-)

diff --git a/tools/perf/builtin-c2c.c b/tools/perf/builtin-c2c.c
index 160b82694d391c50..1856cccbee27818b 100644
--- a/tools/perf/builtin-c2c.c
+++ b/tools/perf/builtin-c2c.c
@@ -2147,6 +2147,8 @@ static int c2c_hists__init(struct c2c_hists *hists,
 			   int nr_header_lines,
 			   struct perf_env *env)
 {
+	int ret;
+
 	__hists__init(&hists->hists, &hists->list);
 
 	/*
@@ -2159,7 +2161,13 @@ static int c2c_hists__init(struct c2c_hists *hists,
 	/* Overload number of header lines.*/
 	hists->list.nr_header_lines = nr_header_lines;
 
-	return hpp_list__parse(&hists->list, /*output=*/NULL, sort, env);
+	ret = hpp_list__parse(&hists->list, /*output=*/NULL, sort, env);
+
+	/* Unregister any formats added before the failure point */
+	if (ret)
+		perf_hpp__reset_output_field(&hists->list);
+
+	return ret;
 }
 
 static int c2c_hists__reinit(struct c2c_hists *c2c_hists,
@@ -2167,8 +2175,16 @@ static int c2c_hists__reinit(struct c2c_hists *c2c_hists,
 			     const char *sort,
 			     struct perf_env *env)
 {
+	int ret;
+
 	perf_hpp__reset_output_field(&c2c_hists->list);
-	return hpp_list__parse(&c2c_hists->list, output, sort, env);
+	ret = hpp_list__parse(&c2c_hists->list, output, sort, env);
+
+	/* Unregister any formats added before the failure point */
+	if (ret)
+		perf_hpp__reset_output_field(&c2c_hists->list);
+
+	return ret;
 }
 
 #define DISPLAY_LINE_LIMIT  0.001
-- 
2.55.0

Re: [PATCH 1/2] perf c2c: Fix error masking, OOM, and unchecked caller errors in hpp_list__parse()

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] Silent error masking and inconsistent propagation for -ENOMEM during sort and output token parsing in setup_sort_list() and setup_output_list().
--

--- Patch [1]: [PATCH 1/2] perf c2c: Fix error masking, OOM, and unchecked caller errors in hpp_list__parse() ---
commit c1a9e4a1694a477755b6abff539aa40b1fed31e1
Author: Arnaldo Carvalho de Melo <acme@redhat.com>

perf c2c: Fix error masking, OOM, and unchecked caller errors in hpp_list__parse()
    
This commit fixes three bugs in hpp_list__parse() by checking strdup()
return values and adding a cleanup label to preserve early errors. It also
converts PARSE_LIST to a function, changing called functions to return
appropriate error codes like -ENOMEM instead of -1 on failure.

> diff --git a/tools/perf/util/sort.c b/tools/perf/util/sort.c
> index 005e7d85dc4a5..616a583e3d4d6 100644
> --- a/tools/perf/util/sort.c
> +++ b/tools/perf/util/sort.c

[ ... ]

> @@ -3869,8 +3877,7 @@ int sort_dimension__add(struct perf_hpp_list *list, const char *tok,
>  				    strlen(tok)))
>  			return -EINVAL;
>  
> -		__sort_dimension__add(sd, list, level);
> -		return 0;
> +		return __sort_dimension__add(sd, list, level);
>  	}
>  
>  	for (i = 0; i < ARRAY_SIZE(memory_sort_dimensions); i++) {

[Severity: Medium]
Since sort_dimension__add() can now return -ENOMEM, could this introduce a
regression where the callers in setup_sort_list() and setup_output_list()
fail to handle the new return value?

Currently, setup_sort_list() only checks for -EINVAL and -ESRCH:

tools/perf/util/sort.c:setup_sort_list() {
    ...
		ret = sort_dimension__add(list, tok, evlist, env, level);
		if (ret == -EINVAL) {
			...
			break;
		} else if (ret == -ESRCH) {
			...
			break;
		}
    ...
}

If sort_dimension__add() returns -ENOMEM, the loop will not break and ret
will be silently overwritten on the next iteration.

A similar issue appears to exist in setup_output_list() which ignores
-ENOMEM from output_field_add().

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260804185830.228763-1-acme@kernel.org?part=1

Re: [PATCH 2/2] perf c2c: Clean up registered formats on c2c_hists__init() and c2c_hists__reinit() failure

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 2 potential issue(s) to consider:

Pre-existing issues:
- [Medium] print_pareto() calls hpp_list__parse() on a local stack variable but never cleans it up, leaking dynamically allocated formats.
- [Medium] kvm_hists__init() and kvm_hists__reinit() suffer from identical partial-registration leaks when format parsing fails.
--

--- Patch [2]: [PATCH 2/2] perf c2c: Clean up registered formats on c2c_hists__init() and c2c_hists__reinit() failure ---
commit 92165e1ae89bef5baeedb3dd8908e10cf564714e
Author: Arnaldo Carvalho de Melo <acme@redhat.com>

perf c2c: Clean up registered formats on c2c_hists__init() and c2c_hists__reinit() failure

When c2c_hists__init() or c2c_hists__reinit() calls hpp_list__parse()
and it fails partway through, format structures registered are left on
the hpp_list. This commit adds cleanup inside both functions to protect
all callers from leaking partially registered entries.

> diff --git a/tools/perf/builtin-c2c.c b/tools/perf/builtin-c2c.c
> index 160b82694d391..1856cccbee278 100644
> --- a/tools/perf/builtin-c2c.c
> +++ b/tools/perf/builtin-c2c.c

[ ... ]

> @@ -2167,8 +2175,16 @@ static int c2c_hists__reinit(struct c2c_hists *c2c_hists,
>  			     const char *sort,
>  			     struct perf_env *env)
>  {
> +	int ret;
> +
>  	perf_hpp__reset_output_field(&c2c_hists->list);
> -	return hpp_list__parse(&c2c_hists->list, output, sort, env);
> +	ret = hpp_list__parse(&c2c_hists->list, output, sort, env);
> +
> +	/* Unregister any formats added before the failure point */
> +	if (ret)
> +		perf_hpp__reset_output_field(&c2c_hists->list);
> +
> +	return ret;
>  }

[Severity: Medium]
This isn't a bug introduced by this patch, but I noticed that print_pareto()
in the same file calls hpp_list__parse() on a local stack variable:

tools/perf/builtin-c2c.c:print_pareto() {
    ...
    ret = hpp_list__parse(&hpp_list, cl_output, /*evlist=*/NULL, env);
    ...
}

Because print_pareto() returns without ever calling 
perf_hpp__reset_output_field(), does it leak all allocated c2c_fmt structures 
on both the success and failure paths?

[Severity: Medium]
This is a pre-existing issue, but kvm_hists__init() and kvm_hists__reinit() in
tools/perf/builtin-kvm.c seem to suffer from identical partial-registration
leaks when format parsing fails:

tools/perf/builtin-kvm.c:kvm_hists__init() {
    ...
    return kvm_hpp_list__parse(&kvm_hists.list, NULL, "ev_name");
}

tools/perf/builtin-kvm.c:kvm_hists__reinit() {
    ...
    return kvm_hpp_list__parse(&kvm_hists.list, output, sort);
}

If parsing fails partway through these functions, will partially allocated
formats remain in the global list without cleanup, replicating the exact leak
pattern fixed here in c2c?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260804185830.228763-1-acme@kernel.org?part=2

[PATCH 2/2] perf c2c: Clean up registered formats on c2c_hists__init() and c2c_hists__reinit() failure

[Arnaldo Carvalho de Melo]

From: Arnaldo Carvalho de Melo <acme@redhat.com>

When c2c_hists__init() or c2c_hists__reinit() calls hpp_list__parse()
and it fails partway through, format structures registered via
perf_hpp_list__column_register() and perf_hpp_list__register_sort_field()
are left on the hpp_list.

In c2c_hists__init(), only one of the callers, c2c_he__alloc_hists(),
handled this with perf_hpp__reset_output_field(), while perf_c2c_report()
did not, leaking the partially registered entries.

In c2c_hists__reinit(), neither perf_c2c_report() nor resort_cl_cb()
clean up on failure.

Fix by adding cleanup inside both functions themselves, so all callers
are protected, and remove the now redundant reset in c2c_he__alloc_hists().

Fixes: 78b275437873 ("perf c2c report: Add sample processing")
Reported-by: sashiko-bot <sashiko-bot@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Assisted-by: Claude:claude-opus-4.6
Assisted-by: Opencode:mimo-v2.5-free
Assisted-by: Opencode:DeepSeek-V4-Flash-free
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/builtin-c2c.c | 21 ++++++++++++++++++---
 1 file changed, 18 insertions(+), 3 deletions(-)

diff --git a/tools/perf/builtin-c2c.c b/tools/perf/builtin-c2c.c
index 160b82694d391c50..bc16a57e092742ad 100644
--- a/tools/perf/builtin-c2c.c
+++ b/tools/perf/builtin-c2c.c
@@ -229,7 +229,6 @@ he__get_c2c_hists(struct hist_entry *he,
 
 	ret = c2c_hists__init(hists, sort, nr_header_lines, env);
 	if (ret) {
-		perf_hpp__reset_output_field(&hists->list);
 		c2c_he->hists = NULL;
 		free(hists);
 		return NULL;
@@ -2147,6 +2146,8 @@ static int c2c_hists__init(struct c2c_hists *hists,
 			   int nr_header_lines,
 			   struct perf_env *env)
 {
+	int ret;
+
 	__hists__init(&hists->hists, &hists->list);
 
 	/*
@@ -2159,7 +2160,13 @@ static int c2c_hists__init(struct c2c_hists *hists,
 	/* Overload number of header lines.*/
 	hists->list.nr_header_lines = nr_header_lines;
 
-	return hpp_list__parse(&hists->list, /*output=*/NULL, sort, env);
+	ret = hpp_list__parse(&hists->list, /*output=*/NULL, sort, env);
+
+	/* Unregister any formats added before the failure point */
+	if (ret)
+		perf_hpp__reset_output_field(&hists->list);
+
+	return ret;
 }
 
 static int c2c_hists__reinit(struct c2c_hists *c2c_hists,
@@ -2167,8 +2174,16 @@ static int c2c_hists__reinit(struct c2c_hists *c2c_hists,
 			     const char *sort,
 			     struct perf_env *env)
 {
+	int ret;
+
 	perf_hpp__reset_output_field(&c2c_hists->list);
-	return hpp_list__parse(&c2c_hists->list, output, sort, env);
+	ret = hpp_list__parse(&c2c_hists->list, output, sort, env);
+
+	/* Unregister any formats added before the failure point */
+	if (ret)
+		perf_hpp__reset_output_field(&c2c_hists->list);
+
+	return ret;
 }
 
 #define DISPLAY_LINE_LIMIT  0.001
-- 
2.55.0

Re: [PATCH 2/2] perf c2c: Clean up registered formats on c2c_hists__init() and c2c_hists__reinit() failure

[Ian Rogers]

On Wed, Aug 5, 2026 at 8:11 AM Arnaldo Carvalho de Melo <acme@kernel.org> wrote:
>
> From: Arnaldo Carvalho de Melo <acme@redhat.com>
>
> When c2c_hists__init() or c2c_hists__reinit() calls hpp_list__parse()
> and it fails partway through, format structures registered via
> perf_hpp_list__column_register() and perf_hpp_list__register_sort_field()
> are left on the hpp_list.
>
> In c2c_hists__init(), only one of the callers, c2c_he__alloc_hists(),
> handled this with perf_hpp__reset_output_field(), while perf_c2c_report()
> did not, leaking the partially registered entries.
>
> In c2c_hists__reinit(), neither perf_c2c_report() nor resort_cl_cb()
> clean up on failure.
>
> Fix by adding cleanup inside both functions themselves, so all callers
> are protected, and remove the now redundant reset in c2c_he__alloc_hists().
>
> Fixes: 78b275437873 ("perf c2c report: Add sample processing")
> Reported-by: sashiko-bot <sashiko-bot@kernel.org>
> Cc: Jiri Olsa <jolsa@kernel.org>
> Assisted-by: Claude:claude-opus-4.6
> Assisted-by: Opencode:mimo-v2.5-free
> Assisted-by: Opencode:DeepSeek-V4-Flash-free
> Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

Reviewed-by: Ian Rogers <irogers@google.com>

Thanks,
Ian

> ---
>  tools/perf/builtin-c2c.c | 21 ++++++++++++++++++---
>  1 file changed, 18 insertions(+), 3 deletions(-)
>
> diff --git a/tools/perf/builtin-c2c.c b/tools/perf/builtin-c2c.c
> index 160b82694d391c50..bc16a57e092742ad 100644
> --- a/tools/perf/builtin-c2c.c
> +++ b/tools/perf/builtin-c2c.c
> @@ -229,7 +229,6 @@ he__get_c2c_hists(struct hist_entry *he,
>
>         ret = c2c_hists__init(hists, sort, nr_header_lines, env);
>         if (ret) {
> -               perf_hpp__reset_output_field(&hists->list);
>                 c2c_he->hists = NULL;
>                 free(hists);
>                 return NULL;
> @@ -2147,6 +2146,8 @@ static int c2c_hists__init(struct c2c_hists *hists,
>                            int nr_header_lines,
>                            struct perf_env *env)
>  {
> +       int ret;
> +
>         __hists__init(&hists->hists, &hists->list);
>
>         /*
> @@ -2159,7 +2160,13 @@ static int c2c_hists__init(struct c2c_hists *hists,
>         /* Overload number of header lines.*/
>         hists->list.nr_header_lines = nr_header_lines;
>
> -       return hpp_list__parse(&hists->list, /*output=*/NULL, sort, env);
> +       ret = hpp_list__parse(&hists->list, /*output=*/NULL, sort, env);
> +
> +       /* Unregister any formats added before the failure point */
> +       if (ret)
> +               perf_hpp__reset_output_field(&hists->list);
> +
> +       return ret;
>  }
>
>  static int c2c_hists__reinit(struct c2c_hists *c2c_hists,
> @@ -2167,8 +2174,16 @@ static int c2c_hists__reinit(struct c2c_hists *c2c_hists,
>                              const char *sort,
>                              struct perf_env *env)
>  {
> +       int ret;
> +
>         perf_hpp__reset_output_field(&c2c_hists->list);
> -       return hpp_list__parse(&c2c_hists->list, output, sort, env);
> +       ret = hpp_list__parse(&c2c_hists->list, output, sort, env);
> +
> +       /* Unregister any formats added before the failure point */
> +       if (ret)
> +               perf_hpp__reset_output_field(&c2c_hists->list);
> +
> +       return ret;
>  }
>
>  #define DISPLAY_LINE_LIMIT  0.001
> --
> 2.55.0
>