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From: "Dmitry V. Levin" <ldv@altlinux.org>
To: ALT Devel discussion list <devel@lists.altlinux.org>
Subject: Re: [devel] [PATCH for apt 2/2 v2] Fix pointer arithmetics
Date: Mon, 9 Dec 2019 01:56:20 +0300
Message-ID: <20191208225620.GB30742@altlinux.org> (raw)
In-Reply-To: <20191207175201.13ca3df6c2cfb01ef559b083@altlinux.org>

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On Sat, Dec 07, 2019 at 05:52:01PM +0300, Andrey Savchenko wrote:
> Hi all!
> 
> On Fri,  6 Dec 2019 18:36:55 +0300 Aleksei Nikiforov wrote:
> > This change should fix pointer arithmetic issues for e2k.
> 
> This commit message is misleading. Pointer arithmetic is broken on
> all architectures, but by pure chance in happens to work correctly
> when gcc is used. On e2k the lcc compiler is used, so problem
> manifests itself. But this doesn't change the fact that pointer
> arithmetic was flawed on all architectures.

Strictly speaking, it's not "broken", it's "UB", but I agree
it is not specific to e2k.

My original commit message for this change was the following:

"Fix UB in pointer arithmetic

Commit 6d5e6a689d07de8feef2cbecb24bc42d5994861b aka 0.5.15lorg2-alt70~9
among other changes introduced UB in pointer arithmetic by casting raw
pointers to specific types."


-- 
ldv

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  reply	other threads:[~2019-12-08 22:56 UTC|newest]

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-12-06 13:16 [devel] [PATCH for apt 1/2] Add option for debugging DynamicMMap::Allocate Aleksei Nikiforov
2019-12-06 13:16 ` [devel] [PATCH for apt 2/2] Fix pointer arithmetics Aleksei Nikiforov
2019-12-06 13:36   ` Ivan A. Melnikov
2019-12-06 15:32     ` Aleksei Nikiforov
2019-12-06 15:36     ` [devel] [PATCH for apt 2/2 v2] " Aleksei Nikiforov
2019-12-07 14:52       ` Andrey Savchenko
2019-12-08 22:56         ` Dmitry V. Levin [this message]
2019-12-09  6:54         ` Aleksei Nikiforov
2019-12-12 19:20           ` Andrey Savchenko
2019-12-13  7:58             ` Aleksei Nikiforov
2019-12-08 23:21       ` Dmitry V. Levin
2019-12-09  7:08         ` Aleksei Nikiforov
2019-12-10  0:07           ` Dmitry V. Levin
2019-12-10  8:18             ` Aleksei Nikiforov
2019-12-10 10:20               ` Dmitry V. Levin
2019-12-10 10:58                 ` Aleksei Nikiforov
2019-12-10 22:20                   ` Dmitry V. Levin
2019-12-11  7:50                     ` Aleksei Nikiforov
2019-12-12 19:43                       ` Andrey Savchenko
2019-12-13  8:01                         ` Aleksei Nikiforov
2019-12-08 23:31   ` [devel] [PATCH for apt 2/2] " Dmitry V. Levin
2019-12-09  7:09     ` Aleksei Nikiforov
2019-12-09  7:16     ` [devel] [PATCH for apt 2/2 v3] " Aleksei Nikiforov
2019-12-09 23:54   ` [devel] [PATCH apt 0/3] Fix 0.5.15lorg2-alt70~9 fallout Dmitry V. Levin
2019-12-09 23:56     ` [devel] [PATCH apt 1/3] apt-pkg/cacheiterators.h: revert #include <set> Dmitry V. Levin
2019-12-09 23:56     ` [devel] [PATCH apt 2/3] apt-pkg/contrib/mmap.cc: revert confusing change of Flags to this->Flags Dmitry V. Levin
2019-12-09 23:56     ` [devel] [PATCH apt 3/3] Fix UB in pointer arithmetic Dmitry V. Levin
2019-12-10  8:18       ` Aleksei Nikiforov
2019-12-08 22:50 ` [devel] [PATCH for apt 1/2] Add option for debugging DynamicMMap::Allocate Dmitry V. Levin
2019-12-09  6:58   ` Aleksei Nikiforov
2019-12-09 10:24     ` Dmitry V. Levin
2019-12-09 11:03       ` [devel] [PATCH for apt 1/2 v3] Add Debug::DynamicMMap::Allocate option Aleksei Nikiforov
2019-12-09 22:59         ` Dmitry V. Levin
2019-12-09  7:00   ` [devel] [PATCH for apt 1/2 v2] Add option for debugging Debug::DynamicMMap::Allocate Aleksei Nikiforov

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