linux-kernel - Re: [PATCH] scsi: be_iscsi: fix possible memory leak and refactor code

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Date:	Sun, 17 Nov 2013 23:12:38 -0200
From:	Geyslan Gregório Bem <geyslan@...il.com>
To:	James Bottomley <James.Bottomley@...senpartnership.com>
Cc:	Jayamohan Kallickal <jayamohan.kallickal@...lex.com>,
	"open list:SERVER ENGINES 10..." <linux-scsi@...r.kernel.org>,
	open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] scsi: be_iscsi: fix possible memory leak and refactor code

2013/11/17 James Bottomley <James.Bottomley@...senpartnership.com>:
> On Sun, 2013-11-17 at 19:09 -0200, Geyslan Gregório Bem wrote:
>> 2013/11/17 James Bottomley <James.Bottomley@...senpartnership.com>:
>> > On Sun, 2013-11-17 at 15:51 -0300, Geyslan G. Bem wrote:
>> >> This patch fix memory leakage in cases 'ISCSI_NET_PARAM_VLAN_ID' and
>> >> 'ISCSI_NET_PARAM_VLAN_PRIORITY' and refactors code 'going out' when
>> >> necessary.
>> >
>> > You pointlessly renamed a variable, which makes the diff hard to read.
>> > Please don't do that.
>>
>> Ok, I can agree. 'len' means length? What is returned in case of non
>> error?
>
> it returns the length of buf written to or negative error.
>
>> > You missed the fact that the passed in pointer is unmodified if
>> > mgmt_get_if_info() returns non zero, so the kfree frees junk and would
>> > oops.
>> >
>> > There's no need for a goto; len = -EINVAL; does everything that's
>> > needed.
>>
>> Well, that is a coverity catch. CID 1128954. Check it.
>
> I didn't say coverity was wrong, I said your patch was (well not wrong,
> just over complex and incomplete).  This is the way to fix both
> problems.
>
> James
>
> ---
>
> diff --git a/drivers/scsi/be2iscsi/be_iscsi.c b/drivers/scsi/be2iscsi/be_iscsi.c
> index ffadbee..9dcbdfa 100644
> --- a/drivers/scsi/be2iscsi/be_iscsi.c
> +++ b/drivers/scsi/be2iscsi/be_iscsi.c
> @@ -541,10 +541,8 @@ static int be2iscsi_get_if_param(struct beiscsi_hba *phba,
>                 ip_type = BE2_IPV6;

James, this approach will not prevent the leakage. We can initialize
the if_info with NULL and always kfree it without to care about junk.

>
>         len = mgmt_get_if_info(phba, ip_type, &if_info);
> -       if (len) {
> -               kfree(if_info);
> +       if (len)
>                 return len;
> -       }
>
>         switch (param) {
>         case ISCSI_NET_PARAM_IPV4_ADDR:
> @@ -569,7 +567,7 @@ static int be2iscsi_get_if_param(struct beiscsi_hba *phba,
>                 break;
>         case ISCSI_NET_PARAM_VLAN_ID:
>                 if (if_info->vlan_priority == BEISCSI_VLAN_DISABLE)
> -                       return -EINVAL;
> +                       len = -EINVAL;
>                 else
>                         len = sprintf(buf, "%d\n",
>                                      (if_info->vlan_priority &
>
>



-- 
Regards,

Geyslan G. Bem
hackingbits.com
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