linux-kernel - Re: [PATCH] netlabel: remove redundant assignment to pointer iter

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Date:   Sun, 1 Sep 2019 19:20:25 +0200
From:   Christophe JAILLET <christophe.jaillet@...adoo.fr>
To:     Paul Moore <paul@...l-moore.com>,
        Colin King <colin.king@...onical.com>
Cc:     "David S . Miller" <davem@...emloft.net>, netdev@...r.kernel.org,
        linux-security-module@...r.kernel.org,
        kernel-janitors@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] netlabel: remove redundant assignment to pointer iter

Le 01/09/2019 à 18:04, Paul Moore a écrit :
> On Sun, Sep 1, 2019 at 11:52 AM Colin King <colin.king@...onical.com> wrote:
>> From: Colin Ian King <colin.king@...onical.com>
>>
>> Pointer iter is being initialized with a value that is never read and
>> is being re-assigned a little later on. The assignment is redundant
>> and hence can be removed.
>>
>> Addresses-Coverity: ("Unused value")
>> Signed-off-by: Colin Ian King <colin.king@...onical.com>
>> ---
>>   net/netlabel/netlabel_kapi.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
> This patch doesn't seem correct to me, at least not in current form.
> At the top of _netlbl_catmap_getnode() is a check to see if iter is
> NULL (as well as a few other checks on iter after that); this patch
> would break that code.
>
> Perhaps we can get rid of the iter/catmap assignment when we define
> iter, but I don't think this patch is the right way to do it.
>
>> diff --git a/net/netlabel/netlabel_kapi.c b/net/netlabel/netlabel_kapi.c
>> index 2b0ef55cf89e..409a3ae47ce2 100644
>> --- a/net/netlabel/netlabel_kapi.c
>> +++ b/net/netlabel/netlabel_kapi.c
>> @@ -607,7 +607,7 @@ static struct netlbl_lsm_catmap *_netlbl_catmap_getnode(
>>    */
>>   int netlbl_catmap_walk(struct netlbl_lsm_catmap *catmap, u32 offset)
>>   {
>> -       struct netlbl_lsm_catmap *iter = catmap;
>> +       struct netlbl_lsm_catmap *iter;
>>          u32 idx;
>>          u32 bit;
>>          NETLBL_CATMAP_MAPTYPE bitmap;
>> --
>> 2.20.1
>

Hi,

'iter' is reassigned a value between the declaration and the NULL test, so removing the first initialization looks good to me.
int  netlbl_catmap_walk(struct  netlbl_lsm_catmap  *catmap,  u32  offset)
{
|

	struct  netlbl_lsm_catmap  *iter  =  catmap;
	u32  idx;
	u32  bit;
	NETLBL_CATMAP_MAPTYPE  bitmap;

	iter  =  _netlbl_catmap_getnode(&catmap,  offset,  _CM_F_WALK,  0);			<-- Here
	if  (iter  ==  NULL)
		return  -ENOENT; This is dead code since commit d960a6184a92 ("netlabel: fix the catmap walking functions") where the call to _netlbl_catmap_getnode has been introduced.

Just my 2c,

CJ|