linux-kernel - [tip:perf/urgent] perf cpumap: Fix writing to illegal memory in handling cpumap mask

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Date:   Thu, 8 Aug 2019 13:19:20 -0700
From:   tip-bot for He Zhe <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     namhyung@...nel.org, alexey.budankov@...ux.intel.com,
        zhe.he@...driver.com, hpa@...or.com, acme@...hat.com,
        peterz@...radead.org, mingo@...nel.org,
        linux-kernel@...r.kernel.org, alexander.shishkin@...ux.intel.com,
        eranian@...gle.com, kan.liang@...ux.intel.com, jolsa@...hat.com,
        tglx@...utronix.de
Subject: [tip:perf/urgent] perf cpumap: Fix writing to illegal memory in
 handling cpumap mask

Commit-ID:  5f5e25f1c7933a6e1673515c0b1d5acd82fea1ed
Gitweb:     https://git.kernel.org/tip/5f5e25f1c7933a6e1673515c0b1d5acd82fea1ed
Author:     He Zhe <zhe.he@...driver.com>
AuthorDate: Fri, 2 Aug 2019 16:29:52 +0800
Committer:  Arnaldo Carvalho de Melo <acme@...hat.com>
CommitDate: Thu, 8 Aug 2019 15:41:10 -0300

perf cpumap: Fix writing to illegal memory in handling cpumap mask

cpu_map__snprint_mask() would write to illegal memory pointed by
zalloc(0) when there is only one cpu.

This patch fixes the calculation and adds sanity check against the input
parameters.

Signed-off-by: He Zhe <zhe.he@...driver.com>
Cc: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
Cc: Alexey Budankov <alexey.budankov@...ux.intel.com>
Cc: Jiri Olsa <jolsa@...hat.com>
Cc: Kan Liang <kan.liang@...ux.intel.com>
Cc: Namhyung Kim <namhyung@...nel.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Stephane Eranian <eranian@...gle.com>
Fixes: 4400ac8a9a90 ("perf cpumap: Introduce cpu_map__snprint_mask()")
Link: http://lkml.kernel.org/r/1564734592-15624-2-git-send-email-zhe.he@windriver.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>
---
 tools/perf/util/cpumap.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/tools/perf/util/cpumap.c b/tools/perf/util/cpumap.c
index 3acfbe34ebaf..39cce66b4ebc 100644
--- a/tools/perf/util/cpumap.c
+++ b/tools/perf/util/cpumap.c
@@ -751,7 +751,10 @@ size_t cpu_map__snprint_mask(struct cpu_map *map, char *buf, size_t size)
 	unsigned char *bitmap;
 	int last_cpu = cpu_map__cpu(map, map->nr - 1);
 
-	bitmap = zalloc((last_cpu + 7) / 8);
+	if (buf == NULL)
+		return 0;
+
+	bitmap = zalloc(last_cpu / 8 + 1);
 	if (bitmap == NULL) {
 		buf[0] = '\0';
 		return 0;