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/
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ath10k@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/ath10k
WARNING: multiple messages have this Message-ID (diff)
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/
next prev parent 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
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