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    Subject[PATCH AUTOSEL 4.19 123/206] perf cpumap: Fix snprintf overflow check
    Date
    From: Christophe JAILLET <christophe.jaillet@wanadoo.fr>

    [ Upstream commit d74b181a028bb5a468f0c609553eff6a8fdf4887 ]

    'snprintf' returns the number of characters which would be generated for
    the given input.

    If the returned value is *greater than* or equal to the buffer size, it
    means that the output has been truncated.

    Fix the overflow test accordingly.

    Fixes: 7780c25bae59f ("perf tools: Allow ability to map cpus to nodes easily")
    Fixes: 92a7e1278005b ("perf cpumap: Add cpu__max_present_cpu()")
    Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
    Suggested-by: David Laight <David.Laight@ACULAB.COM>
    Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
    Cc: Don Zickus <dzickus@redhat.com>
    Cc: He Zhe <zhe.he@windriver.com>
    Cc: Jan Stancek <jstancek@redhat.com>
    Cc: Jiri Olsa <jolsa@redhat.com>
    Cc: Kan Liang <kan.liang@linux.intel.com>
    Cc: Mark Rutland <mark.rutland@arm.com>
    Cc: Namhyung Kim <namhyung@kernel.org>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: kernel-janitors@vger.kernel.org
    Link: http://lore.kernel.org/lkml/20200324070319.10901-1-christophe.jaillet@wanadoo.fr
    Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    tools/perf/util/cpumap.c | 10 +++++-----
    1 file changed, 5 insertions(+), 5 deletions(-)

    diff --git a/tools/perf/util/cpumap.c b/tools/perf/util/cpumap.c
    index f93846edc1e0d..827d844f4efb1 100644
    --- a/tools/perf/util/cpumap.c
    +++ b/tools/perf/util/cpumap.c
    @@ -462,7 +462,7 @@ static void set_max_cpu_num(void)

    /* get the highest possible cpu number for a sparse allocation */
    ret = snprintf(path, PATH_MAX, "%s/devices/system/cpu/possible", mnt);
    - if (ret == PATH_MAX) {
    + if (ret >= PATH_MAX) {
    pr_err("sysfs path crossed PATH_MAX(%d) size\n", PATH_MAX);
    goto out;
    }
    @@ -473,7 +473,7 @@ static void set_max_cpu_num(void)

    /* get the highest present cpu number for a sparse allocation */
    ret = snprintf(path, PATH_MAX, "%s/devices/system/cpu/present", mnt);
    - if (ret == PATH_MAX) {
    + if (ret >= PATH_MAX) {
    pr_err("sysfs path crossed PATH_MAX(%d) size\n", PATH_MAX);
    goto out;
    }
    @@ -501,7 +501,7 @@ static void set_max_node_num(void)

    /* get the highest possible cpu number for a sparse allocation */
    ret = snprintf(path, PATH_MAX, "%s/devices/system/node/possible", mnt);
    - if (ret == PATH_MAX) {
    + if (ret >= PATH_MAX) {
    pr_err("sysfs path crossed PATH_MAX(%d) size\n", PATH_MAX);
    goto out;
    }
    @@ -586,7 +586,7 @@ int cpu__setup_cpunode_map(void)
    return 0;

    n = snprintf(path, PATH_MAX, "%s/devices/system/node", mnt);
    - if (n == PATH_MAX) {
    + if (n >= PATH_MAX) {
    pr_err("sysfs path crossed PATH_MAX(%d) size\n", PATH_MAX);
    return -1;
    }
    @@ -601,7 +601,7 @@ int cpu__setup_cpunode_map(void)
    continue;

    n = snprintf(buf, PATH_MAX, "%s/%s", path, dent1->d_name);
    - if (n == PATH_MAX) {
    + if (n >= PATH_MAX) {
    pr_err("sysfs path crossed PATH_MAX(%d) size\n", PATH_MAX);
    continue;
    }
    --
    2.25.1
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