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* [PATCH V2] perf cpumap: Fix snprintf overflow check
@ 2020-03-24  7:03 Christophe JAILLET
  2020-03-24 12:50 ` Arnaldo Carvalho de Melo
  2020-04-04  8:41 ` [tip: perf/urgent] " tip-bot2 for Christophe JAILLET
  0 siblings, 2 replies; 5+ messages in thread
From: Christophe JAILLET @ 2020-03-24  7:03 UTC (permalink / raw)
  To: peterz, mingo, acme, mark.rutland, alexander.shishkin, jolsa,
	namhyung, kan.liang, zhe.he, dzickus, jstancek
  Cc: linux-kernel, kernel-janitors, Christophe JAILLET

'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 accordingling.

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>
---
V2: keep snprintf
    modifiy the tests for truncated output
    Update subject and description
---
 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;
 		}
-- 
2.20.1


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2020-03-24  7:03 [PATCH V2] perf cpumap: Fix snprintf overflow check Christophe JAILLET
2020-03-24 12:50 ` Arnaldo Carvalho de Melo
2020-03-24 14:44   ` Christophe JAILLET
2020-03-25 12:19     ` Arnaldo Carvalho de Melo
2020-04-04  8:41 ` [tip: perf/urgent] " tip-bot2 for Christophe JAILLET

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