From: Christophe JAILLET <christophe.jail...@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.jail...@wanadoo.fr>
Suggested-by: David Laight <david.lai...@aculab.com>
Cc: Alexander Shishkin <alexander.shish...@linux.intel.com>
Cc: Don Zickus <dzic...@redhat.com>
Cc: He Zhe <zhe...@windriver.com>
Cc: Jan Stancek <jstan...@redhat.com>
Cc: Jiri Olsa <jo...@redhat.com>
Cc: Kan Liang <kan.li...@linux.intel.com>
Cc: Mark Rutland <mark.rutl...@arm.com>
Cc: Namhyung Kim <namhy...@kernel.org>
Cc: Peter Zijlstra <pet...@infradead.org>
Cc: kernel-janit...@vger.kernel.org
Link: 
http://lore.kernel.org/lkml/20200324070319.10901-1-christophe.jail...@wanadoo.fr
Signed-off-by: Arnaldo Carvalho de Melo <a...@redhat.com>
Signed-off-by: Sasha Levin <sas...@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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