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    Subject[PATCH AUTOSEL 4.19 64/68] perf cpumap: Fix writing to illegal memory in handling cpumap mask
    Date
    From: He Zhe <zhe.he@windriver.com>

    [ Upstream commit 5f5e25f1c7933a6e1673515c0b1d5acd82fea1ed ]

    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@windriver.com>
    Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
    Cc: Alexey Budankov <alexey.budankov@linux.intel.com>
    Cc: Jiri Olsa <jolsa@redhat.com>
    Cc: Kan Liang <kan.liang@linux.intel.com>
    Cc: Namhyung Kim <namhyung@kernel.org>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Stephane Eranian <eranian@google.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@redhat.com>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    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 383674f448fcd..f93846edc1e0d 100644
    --- a/tools/perf/util/cpumap.c
    +++ b/tools/perf/util/cpumap.c
    @@ -701,7 +701,10 @@ 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;
    --
    2.20.1
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