linux-kernel - [PATCH v1 02/25] perf pmu: Avoid a path name copy

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20230823080828.1460376-3-irogers@google.com>
Date:   Wed, 23 Aug 2023 01:08:05 -0700
From:   Ian Rogers <irogers@...gle.com>
To:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>,
        Ian Rogers <irogers@...gle.com>,
        Adrian Hunter <adrian.hunter@...el.com>,
        James Clark <james.clark@....com>,
        Kan Liang <kan.liang@...ux.intel.com>,
        John Garry <john.g.garry@...cle.com>,
        Kajol Jain <kjain@...ux.ibm.com>,
        Jing Zhang <renyu.zj@...ux.alibaba.com>,
        Ravi Bangoria <ravi.bangoria@....com>,
        Rob Herring <robh@...nel.org>,
        Gaosheng Cui <cuigaosheng1@...wei.com>,
        linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH v1 02/25] perf pmu: Avoid a path name copy

Rather than read a base path and append into a 2nd path, read the base
path directly into output buffer and append to that.

Signed-off-by: Ian Rogers <irogers@...gle.com>
---
 tools/perf/util/pmu.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
index a7f05e4dda97..7683c6749d66 100644
--- a/tools/perf/util/pmu.c
+++ b/tools/perf/util/pmu.c
@@ -1756,17 +1756,19 @@ int perf_pmu__event_source_devices_fd(void)
  * then pathname will be filled with
  * "/sys/bus/event_source/devices/cs_etm/format"
  *
- * Return 0 if the sysfs mountpoint couldn't be found or if no
- * characters were written.
+ * Return 0 if the sysfs mountpoint couldn't be found, if no characters were
+ * written or if the buffer size is exceeded.
  */
 int perf_pmu__pathname_scnprintf(char *buf, size_t size,
 				 const char *pmu_name, const char *filename)
 {
-	char base_path[PATH_MAX];
+	size_t len;
 
-	if (!perf_pmu__event_source_devices_scnprintf(base_path, sizeof(base_path)))
+	len = perf_pmu__event_source_devices_scnprintf(buf, size);
+	if (!len || (len + strlen(pmu_name) + strlen(filename) + 1)  >= size)
 		return 0;
-	return scnprintf(buf, size, "%s%s/%s", base_path, pmu_name, filename);
+
+	return scnprintf(buf + len, size - len, "%s/%s", pmu_name, filename);
 }
 
 int perf_pmu__pathname_fd(int dirfd, const char *pmu_name, const char *filename, int flags)
-- 
2.42.0.rc1.204.g551eb34607-goog