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

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Date:	Mon, 18 Nov 2013 06:58:27 -0800
From:	James Bottomley <James.Bottomley@...senPartnership.com>
To:	Geyslan Gregório Bem <geyslan@...il.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

On Sun, 2013-11-17 at 23:12 -0200, Geyslan Gregório Bem wrote:
> 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.

I don't see why not.  The -EINVAL case goes through the kfree() now too,
no?

>  We can initialize the if_info with NULL and always kfree it without
> to care about junk.

Why?  Error return means no allocation.

James


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