linux-kernel - Re: [PATCH] fs/9p: Initialize status in v9fs_file_do

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Message-ID: <20150109130723.GA3183@u-isr-ctg-01>
Date:	Fri, 9 Jan 2015 14:07:23 +0100
From:	Dominique Martinet <dominique.martinet@....fr>
To:	"Kirill A. Shutemov" <kirill@...temov.name>
CC:	Eric Van Hensbergen <ericvh@...il.com>,
	Ron Minnich <rminnich@...dia.gov>,
	Latchesar Ionkov <lucho@...kov.net>,
	<v9fs-developer@...ts.sourceforge.net>,
	<linux-fsdevel@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] fs/9p: Initialize status in v9fs_file_do_lock.

Kirill A. Shutemov wrote on Fri, Jan 09, 2015 at 02:33:53PM +0200:
> On Fri, Jan 09, 2015 at 12:56:07PM +0100, Dominique Martinet wrote:
> > If p9_client_lock_dotl returns an error, status is possibly never filled
> > but will be used in the following switch.
> > Initializing it to P9_LOCK_ERROR makes sur we will return an error and
> > cleanup (and not hit the default case).
> 
> That's what my patch[1] fixes.
> 
> http://marc.info/?i=1419858019-116944-1-git-send-email-kirill.shutemov%40linux.intel.com

Actually, it's slightly different and still worth adding (mine if we
apply your's first and your's if we apply mine first - don't think
they'll conflict. I even reworded the (too old!) commit message to fit
with your patch :))

Your patch will not BUG() if status is junk, BUT if status uninitialized
value is 0 and p9_client_lock_dotl then we'll return res=0 (success) and
not unlock before returning. My patch makes sure we'll return -ENOLCK.

Likewise, if we only apply my patch then a rogue server could BUG() a
client, so we want your's anyway.

-- 
Dominique Martinet,
CEA

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