[PATCHES v6 0/2] perf c2c hardening

[PATCHES v6 0/2] perf c2c hardening

[Arnaldo Carvalho de Melo]

Hi,

Fixes for 'perf c2c' found by the sashiko-bot AI reviewer.

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

Patch 2 fixes a format list leak: when c2c_hists__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 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).



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() failure

 tools/perf/builtin-c2c.c | 95 +++++++++++++++++++++++++++++-----------
 tools/perf/util/sort.c   | 38 +++++++++-------
 2 files changed, 91 insertions(+), 42 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

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:

Pre-existing issues:
- [Medium] The string parsing loops in `setup_sort_list()` and `setup_output_list()` silently ignore and overwrite memory allocation errors (-ENOMEM), leading to partially initialized sort or output fields being treated as successful.
--

--- Patch [1]: [PATCH 1/2] perf c2c: Fix error masking, OOM, and unchecked caller errors in hpp_list__parse() ---
commit eb21379d23b3ae985cd662b484d5da281ac1387b
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 multiple issues in hpp_list__parse(), including error
masking during string parsing, unhandled strdup() OOM failures, and unchecked
function returns. It also updates underlying sort and output functions to
return -ENOMEM instead of -1 on allocation failures.

> 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
[ ... ]
> @@ -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++) {

[Severity: Medium]
This is a pre-existing issue, but by explicitly propagating -ENOMEM out of
sort_dimension__add() and output_field_add(), does this highlight a bug in
their callers?

In setup_sort_list() and setup_output_list(), the parsing loops only check
for -EINVAL and -ESRCH:

ret = sort_dimension__add(list, tok, evlist, env, level);
if (ret == -EINVAL) {
	...
	break;
} else if (ret == -ESRCH) {
	...
	break;
}

If sort_dimension__add() or output_field_add() returns -ENOMEM, the loop
continues without breaking, and a subsequent successful token will overwrite
the error. This can cause the perf tool to silently continue with a partially
configured state instead of aborting on memory allocation failure.

Should these loops be updated to catch other error codes like -ENOMEM?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260803180703.194916-1-acme@kernel.org?part=1

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

[Arnaldo Carvalho de Melo]

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

When c2c_hists__init() 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.  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.

Fix by adding cleanup inside c2c_hists__init() itself, 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
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/builtin-c2c.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/tools/perf/builtin-c2c.c b/tools/perf/builtin-c2c.c
index 160b82694d391c50..a01fa1655569cac9 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,
-- 
2.55.0

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

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:

Pre-existing issues:
- [High] perf_hpp__setup_output_field() and perf_hpp__append_sort_keys() corrupt the global perf_hpp_list and fail to populate the provided local list.
--

--- Patch [2]: [PATCH 2/2] perf c2c: Clean up registered formats on c2c_hists__init() failure ---
commit 0cc1bae097f820bedd8cd5517b56916ee9c48ca3
Author: Arnaldo Carvalho de Melo <acme@redhat.com>

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

When c2c_hists__init() calls hpp_list__parse() and it fails partway through,
format structures registered are left on the hpp_list. This fix adds cleanup
inside c2c_hists__init() itself so all callers are protected.

> diff --git a/tools/perf/builtin-c2c.c b/tools/perf/builtin-c2c.c
> index 160b82694d391..a01fa1655569c 100644
> --- a/tools/perf/builtin-c2c.c
> +++ b/tools/perf/builtin-c2c.c

[ ... ]

> @@ -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);

[Severity: High]
This isn't a bug introduced by this patch, but will calling hpp_list__parse()
corrupt the global perf_hpp_list?

When c2c initializes its local hpp_list, hpp_list__parse() eventually leads
to calls to perf_hpp__setup_output_field() and perf_hpp__append_sort_keys()
in tools/perf/ui/hist.c. Both of these functions accept a local
struct perf_hpp_list *list parameter, but they appear to use the global list
wrappers instead of modifying the passed local list:

tools/perf/ui/hist.c:perf_hpp__setup_output_field() {
    ...
    perf_hpp__column_register(fmt);
    ...
}

tools/perf/ui/hist.c:perf_hpp__append_sort_keys() {
    ...
    perf_hpp__register_sort_field(fmt);
    ...
}

Could this cause the local lists to miss output columns, while also polluting
the global list with dangling pointers to dynamically allocated local formats?

Should these functions be updated to call
perf_hpp_list__column_register(list, fmt) and
perf_hpp_list__register_sort_field(list, fmt) instead?

> +
> +	/* Unregister any formats added before the failure point */
> +	if (ret)
> +		perf_hpp__reset_output_field(&hists->list);
> +
> +	return ret;
>  }
>

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260803180703.194916-1-acme@kernel.org?part=2