linux-kernel - [PATCH] cgroup: limit max copied char length for cgroup file name

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Date:   Sat, 9 Dec 2017 13:47:58 +0800
From:   Ma Shimiao <mashimiao.fnst@...fujitsu.com>
To:     <tj@...nel.org>, <lizefan@...wei.com>
CC:     <cgroups@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        Ma Shimiao <mashimiao.fnst@...fujitsu.com>
Subject: [PATCH] cgroup: limit max copied char length for cgroup file name

the result of cgroup_file_name will be used by kernfs_remove_name,
and then by kernfs_remove_by_name_ns().
If reached the max length, may have problem printed by WARN() in
kernfs_remove_by_name_ns().

Signed-off-by: Ma Shimiao <mashimiao.fnst@...fujitsu.com>
---
 kernel/cgroup/cgroup.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
index 0b1ffe147f24..7f588d1617c5 100644
--- a/kernel/cgroup/cgroup.c
+++ b/kernel/cgroup/cgroup.c
@@ -1397,7 +1397,7 @@ static char *cgroup_file_name(struct cgroup *cgrp, const struct cftype *cft,
 			 cgroup_on_dfl(cgrp) ? ss->name : ss->legacy_name,
 			 cft->name);
 	else
-		strncpy(buf, cft->name, CGROUP_FILE_NAME_MAX);
+		strncpy(buf, cft->name, CGROUP_FILE_NAME_MAX - 1);
 	return buf;
 }
 
-- 
2.13.6