From: Martin Sebor <msebor@gmail.com>
To: Paul Eggert <eggert@cs.ucla.edu>
Cc: libc-alpha@sourceware.org
Subject: Re: [PATCH] avoid -Wuse-after-free [BZ #26779]
Date: Mon, 24 Jan 2022 17:42:53 -0700 [thread overview]
Message-ID: <62758b96-42b1-c199-0bf1-975ca4b70cb0@gmail.com> (raw)
In-Reply-To: <e55d3e28-74b0-3b65-ae9b-ea6356a05b36@cs.ucla.edu>
On 1/21/22 17:42, Paul Eggert wrote:
> On 1/21/22 15:14, Martin Sebor wrote:
>>>
>>
>> That does look cleaner although it wasn't entirely obvious to me
>> from looking at the code that it's the same. Unfortunately, it
>> doesn't help. GCC replaces the bool variable with the equality
>> test of the two pointers, and the warning points that out.
>
> That's a GCC bug.
>
>> Pedantically speaking it's a bug in GCC that it does that but
>> I doubt anyone would care to do anything about it.
>
> You might be surprised; they do fix bugs in this area. If I could
> reproduce the bug I'd file a bug report, but my GCC doesn't complain so
> I guess it's up to you....
I opened a GCC bug for the record:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104215
GCC 12 is now in its regression-fixing stage so to get it fixed we'd
need to make it a regression. That's usually only done for bugs that
trigger under conditions where they didn't before.
>> his only
>> happens at level 3 (i.e., above the default 2), so if you want
>> a clean build at that level you can either take the patch as is
>> or use #pragma GCC diagnostic to suppress the warning. Otherwise,
>> if all you care about is -Wall, then you can drop this part of
>> the patch.
>
> We shouldn't drop the patch or use a pragma, since this is a genuine bug
> in glibc that should get fixed. If the only option is to use the patch
> as-is then let's do that. Though I do wish the GCC bug were fixed.
As do I, but I'm not holding my breath.
I will post an updated/broken down patch series shortly.
Martin
next prev parent reply other threads:[~2022-01-25 0:42 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-16 0:21 Martin Sebor
2022-01-16 2:25 ` Paul Eggert
2022-01-21 23:14 ` Martin Sebor
2022-01-22 0:42 ` Paul Eggert
2022-01-25 0:42 ` Martin Sebor [this message]
2022-01-25 1:08 ` Jeff Law
2022-01-18 9:48 ` Florian Weimer
2022-01-20 21:50 ` Martin Sebor
2022-01-25 0:52 ` [PATCH v2 0/5] " Martin Sebor
2022-01-25 0:57 ` [PATCH v2 1/5] " Martin Sebor
2022-01-25 17:46 ` Carlos O'Donell
2022-01-25 0:58 ` [PATCH v2 2/5] " Martin Sebor
2022-01-25 17:46 ` Carlos O'Donell
2022-01-25 0:58 ` [PATCH v2 3/5] " Martin Sebor
2022-01-25 17:47 ` Carlos O'Donell
2022-01-25 0:58 ` [PATCH v2 4/5] " Martin Sebor
2022-01-25 17:49 ` Carlos O'Donell
2022-01-25 17:51 ` Carlos O'Donell
2022-01-25 21:47 ` Florian Weimer
2022-01-26 13:55 ` Carlos O'Donell
2022-01-25 0:58 ` [PATCH v2 5/5] " Martin Sebor
2022-01-25 17:49 ` Carlos O'Donell
2022-01-25 22:50 ` [PATCH v3 " Martin Sebor
2022-01-26 14:56 ` Carlos O'Donell
2022-01-28 13:10 ` Joseph Myers
2022-01-28 17:33 ` Carlos O'Donell
2022-01-28 17:51 ` Joseph Myers
2022-01-28 23:21 ` Jeff Law
2022-01-31 15:12 ` Carlos O'Donell
2022-02-04 20:40 ` Joseph Myers
2022-01-25 17:46 ` [PATCH v2 0/5] " Carlos O'Donell
2022-01-26 3:08 ` Martin Sebor
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