All of lore.kernel.org
 help / color / mirror / Atom feed
From: Bob Copeland <me@bobcopeland.com>
To: Johannes Berg <johannes@sipsolutions.net>
Cc: Michal Kazior <michal.kazior@tieto.com>,
	linux-wireless <linux-wireless@vger.kernel.org>,
	"ath10k@lists.infradead.org" <ath10k@lists.infradead.org>
Subject: Re: [PATCH] ath10k: fix potential null dereference bugs
Date: Mon, 13 Jun 2016 09:05:07 -0400	[thread overview]
Message-ID: <20160613130507.GA11074@localhost> (raw)
In-Reply-To: <1465808939.2434.1.camel@sipsolutions.net>

On Mon, Jun 13, 2016 at 11:08:59AM +0200, Johannes Berg wrote:
> On Mon, 2016-06-13 at 07:39 +0200, Michal Kazior wrote:
> > 
> > FWIW all of these are false positives. I think this was already
> > pointed out some time ago. The drv_priv stuff is merely an offset
> > (see how ieee80211_vif and ieee80211_sta are defined) and the
> > according structure is always checked beforehand.

OK, fair enough, sorry for the noise.  I'm daily running sparse / smatch
on wireless-testing; although these had been around for a while they
showed up as new "errors" because of some line number changes, but I'll
squelch them going forward.

> IIRC, doing something like that can (sometimes?) still get you into
> undefined behaviour territory, so the compiler could potentially
> "optimize" away the later NULL check.

So I did just go and check the generated code for each of these cases
and gcc didn't elide the subsequent if-test, at least on x86-64 and my
compiler / build config.  Given http://lwn.net/Articles/342330, it seems
possible, though.

-- 
Bob Copeland %% http://bobcopeland.com/

WARNING: multiple messages have this Message-ID (diff)
From: Bob Copeland <me@bobcopeland.com>
To: Johannes Berg <johannes@sipsolutions.net>
Cc: linux-wireless <linux-wireless@vger.kernel.org>,
	Michal Kazior <michal.kazior@tieto.com>,
	"ath10k@lists.infradead.org" <ath10k@lists.infradead.org>
Subject: Re: [PATCH] ath10k: fix potential null dereference bugs
Date: Mon, 13 Jun 2016 09:05:07 -0400	[thread overview]
Message-ID: <20160613130507.GA11074@localhost> (raw)
In-Reply-To: <1465808939.2434.1.camel@sipsolutions.net>

On Mon, Jun 13, 2016 at 11:08:59AM +0200, Johannes Berg wrote:
> On Mon, 2016-06-13 at 07:39 +0200, Michal Kazior wrote:
> > 
> > FWIW all of these are false positives. I think this was already
> > pointed out some time ago. The drv_priv stuff is merely an offset
> > (see how ieee80211_vif and ieee80211_sta are defined) and the
> > according structure is always checked beforehand.

OK, fair enough, sorry for the noise.  I'm daily running sparse / smatch
on wireless-testing; although these had been around for a while they
showed up as new "errors" because of some line number changes, but I'll
squelch them going forward.

> IIRC, doing something like that can (sometimes?) still get you into
> undefined behaviour territory, so the compiler could potentially
> "optimize" away the later NULL check.

So I did just go and check the generated code for each of these cases
and gcc didn't elide the subsequent if-test, at least on x86-64 and my
compiler / build config.  Given http://lwn.net/Articles/342330, it seems
possible, though.

-- 
Bob Copeland %% http://bobcopeland.com/

_______________________________________________
ath10k mailing list
ath10k@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/ath10k

  reply	other threads:[~2016-06-13 13:05 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-06-10 12:52 [PATCH] ath10k: fix potential null dereference bugs Bob Copeland
2016-06-10 12:52 ` Bob Copeland
2016-06-13  5:39 ` Michal Kazior
2016-06-13  5:39   ` Michal Kazior
2016-06-13  9:08   ` Johannes Berg
2016-06-13  9:08     ` Johannes Berg
2016-06-13 13:05     ` Bob Copeland [this message]
2016-06-13 13:05       ` Bob Copeland
2016-06-13 13:18       ` Johannes Berg
2016-06-13 13:18         ` Johannes Berg
2016-06-14 13:51         ` Valo, Kalle
2016-06-14 13:51           ` Valo, Kalle
2016-06-14 14:16           ` Bob Copeland
2016-06-14 14:16             ` Bob Copeland
2016-06-14 14:39             ` Valo, Kalle
2016-06-14 14:39               ` Valo, Kalle
2016-06-14 13:53 ` Valo, Kalle
2016-06-14 13:53   ` Valo, Kalle
2016-06-30 10:54 ` Kalle Valo
2016-06-30 10:54   ` Kalle Valo

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20160613130507.GA11074@localhost \
    --to=me@bobcopeland.com \
    --cc=ath10k@lists.infradead.org \
    --cc=johannes@sipsolutions.net \
    --cc=linux-wireless@vger.kernel.org \
    --cc=michal.kazior@tieto.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.