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

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

[Ma Shimiao]

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-BthXqXjhjHXQFUHtdCDX3A@public.gmane.org>
---
 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

Re: [PATCH] cgroup: limit max copied char length for cgroup file name

[Tejun Heo]

On Sat, Dec 09, 2017 at 01:47:58PM +0800, Ma Shimiao wrote:
> 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-BthXqXjhjHXQFUHtdCDX3A@public.gmane.org>

Can we use strscpy() instead?

Thanks.

-- 
tejun

Re: [PATCH] cgroup: limit max copied char length for cgroup file name

[Ma Shimiao]

On 12/11/2017 11:05 PM, Tejun Heo wrote:
> On Sat, Dec 09, 2017 at 01:47:58PM +0800, Ma Shimiao wrote:
>> 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-BthXqXjhjHXQFUHtdCDX3A@public.gmane.org>
> 
> Can we use strscpy() instead?

OK, I will update the patch
> 
> Thanks.
> 


-- 
Ma Shimiao
Development Dept.I
Nanjing Fujitsu Nanda Software Tech. Co., Ltd.(FNST)