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From: Bob Copeland <me@bobcopeland.com>
To: "Valo, Kalle" <kvalo@qca.qualcomm.com>
Cc: Johannes Berg <johannes@sipsolutions.net>,
	linux-wireless <linux-wireless@vger.kernel.org>,
	"michal.kazior@tieto.com" <michal.kazior@tieto.com>,
	"ath10k@lists.infradead.org" <ath10k@lists.infradead.org>
Subject: Re: [PATCH] ath10k: fix potential null dereference bugs
Date: Tue, 14 Jun 2016 10:16:06 -0400	[thread overview]
Message-ID: <20160614141606.GA713@localhost> (raw)
In-Reply-To: <87shwf3mlh.fsf@kamboji.qca.qualcomm.com>

On Tue, Jun 14, 2016 at 01:51:24PM +0000, Kalle Valo wrote:
> > It's not clear that's the same situation, since tun->sk is very likely
> > to have been an actual pointer, not an embedded thing like drv_priv.

Just to follow up on that thread, I did research it a bit yesterday and
came to the conclusion that it is UB even when the target is in the same
struct.  However, in a not very scientific survey, I didn't see either clang
or gcc remove the test in a simplified test case (with -O3 and without
-fno-delete-null-pointer-checks).  If drv_priv were an actual pointer, gcc
did remove it but clang did not.  So, there's that.

> > However, with all this, I think I'd simply not take any chances - the
> > patch isn't exactly invasive and in some cases (for example the first
> > hunk of the patch) will even improve the code to the point where the
> > compiler could warn about uninitialized usage of the pointer when the
> > code gets modified to use it in case of !txq->sta.
> >
> > I'd take it, but I guess it's Kalle's decision :)
> 
> Yeah, I'm leaning towards Johannes. These are not really invasive.

Thanks, and sorry about the checkpatch -- I did run checkpatch on it but
for some reason my version only complained about some of them.

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

WARNING: multiple messages have this Message-ID (diff)
From: Bob Copeland <me@bobcopeland.com>
To: "Valo, Kalle" <kvalo@qca.qualcomm.com>
Cc: Johannes Berg <johannes@sipsolutions.net>,
	linux-wireless <linux-wireless@vger.kernel.org>,
	"michal.kazior@tieto.com" <michal.kazior@tieto.com>,
	"ath10k@lists.infradead.org" <ath10k@lists.infradead.org>
Subject: Re: [PATCH] ath10k: fix potential null dereference bugs
Date: Tue, 14 Jun 2016 10:16:06 -0400	[thread overview]
Message-ID: <20160614141606.GA713@localhost> (raw)
In-Reply-To: <87shwf3mlh.fsf@kamboji.qca.qualcomm.com>

On Tue, Jun 14, 2016 at 01:51:24PM +0000, Kalle Valo wrote:
> > It's not clear that's the same situation, since tun->sk is very likely
> > to have been an actual pointer, not an embedded thing like drv_priv.

Just to follow up on that thread, I did research it a bit yesterday and
came to the conclusion that it is UB even when the target is in the same
struct.  However, in a not very scientific survey, I didn't see either clang
or gcc remove the test in a simplified test case (with -O3 and without
-fno-delete-null-pointer-checks).  If drv_priv were an actual pointer, gcc
did remove it but clang did not.  So, there's that.

> > However, with all this, I think I'd simply not take any chances - the
> > patch isn't exactly invasive and in some cases (for example the first
> > hunk of the patch) will even improve the code to the point where the
> > compiler could warn about uninitialized usage of the pointer when the
> > code gets modified to use it in case of !txq->sta.
> >
> > I'd take it, but I guess it's Kalle's decision :)
> 
> Yeah, I'm leaning towards Johannes. These are not really invasive.

Thanks, and sorry about the checkpatch -- I did run checkpatch on it but
for some reason my version only complained about some of them.

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

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

  reply	other threads:[~2016-06-14 14:16 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
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 [this message]
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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