linux-kernel - Re: [PATCH] Use strscpy() instead of strcpy()

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Message-ID: <e7cfb6b2-51a4-4c8e-9c43-20653bd1443f@wanadoo.fr>
Date: Wed, 13 Nov 2024 22:28:36 +0100
From: Christophe JAILLET <christophe.jaillet@...adoo.fr>
To: Abdul Rahim <abdul.rahim@...ahoo.com>
Cc: xiubli@...hat.com, idryomov@...il.com, ceph-devel@...r.kernel.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Use strscpy() instead of strcpy()

Le 13/11/2024 à 21:15, Abdul Rahim a écrit :
> On Tue, Nov 12, 2024 at 07:21:54AM +0100, Christophe JAILLET wrote:
>> Le 11/11/2024 ï¿½ 23:10, Abdul Rahim a ï¿½critï¿½:
>>> strcpy() is generally considered unsafe and use of strscpy() is
>>> recommended [1]
>>>
>>> this fixes checkpatch warning:
>>>       WARNING: Prefer strscpy over strcpy
>>>
>>> Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strcpy [1]
>>> Signed-off-by: Abdul Rahim <abdul.rahim@...ahoo.com>
>>> ---
>>>    fs/ceph/export.c | 2 +-
>>>    1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/fs/ceph/export.c b/fs/ceph/export.c
>>> index 44451749c544..0e5b3c7b3756 100644
>>> --- a/fs/ceph/export.c
>>> +++ b/fs/ceph/export.c
>>> @@ -452,7 +452,7 @@ static int __get_snap_name(struct dentry *parent, char *name,
>>>    		goto out;
>>>    	if (ceph_snap(inode) == CEPH_SNAPDIR) {
>>>    		if (ceph_snap(dir) == CEPH_NOSNAP) {
>>> -			strcpy(name, fsc->mount_options->snapdir_name);
>>> +			strscpy(name, fsc->mount_options->snapdir_name);
>>
>> This does not compile because when the size of 'name' is not known at
>> compilation time, you need to use the 3-argument version of strscpy().
>>
>> Please always compile test your patches before sending them. Even, when the
>> change looks trivial.
>>
> 
> Sure.
> 
>> CJ
>>
>>>    			err = 0;
>>>    		}
>>>    		goto out;
>>
>>
> 
> Should it be: NAME_MAX+1 ?
> 
> See: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/include/linux/exportfs.h?h=v6.12-rc7#n203
> 
> 

Looks like a good idea, maybe with a comment related to get_name() in 
the export_operations structure, so that we remind where this limit 
comes from?

CJ