From: Christophe JAILLET <christophe.jaillet@wanadoo.fr>

Date: Tue, 24 Mar 2020 08:03:19 +0100

Subject: perf cpumap: Fix snprintf overflow check

Git-commit: d74b181a028bb5a468f0c609553eff6a8fdf4887

Patch-mainline: v5.7-rc1

References: git-fixes

​

'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: Tony Jones <tonyj@suse.de>

---

 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 983b7388f22b..dc5c5e6fc502 100644

--- a/tools/perf/util/cpumap.c

+++ b/tools/perf/util/cpumap.c

@@ -317,7 +317,7 @@ 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;

    }

@@ -328,7 +328,7 @@ 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;

    }

@@ -356,7 +356,7 @@ 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;

    }

@@ -441,7 +441,7 @@ 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;

    }

@@ -456,7 +456,7 @@ 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;

        }

​

​