Re: A Famous Security Bug

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Sujet : Re: A Famous Security Bug
De : 433-929-6894 (at) *nospam* kylheku.com (Kaz Kylheku)
Groupes : comp.lang.c
Date : 22. Mar 2024, 17:33:03
Autres entêtes
Organisation : A noiseless patient Spider
Message-ID : <20240322083037.20@kylheku.com>
References : 1 2 3 4 5
User-Agent : slrn/pre1.0.4-9 (Linux)
On 2024-03-22, David Brown <david.brown@hesbynett.no> wrote:
On 21/03/2024 21:21, Kaz Kylheku wrote:
>
Eliminating dead stores is a very basic dataflow-driven optimization.
 
Because memset is part of the C language, the compiler knows
exactly what effect it has (that it's equivalent to setting
all the bytes to zero, like a sequence of assignments).
 
>
Yes.
>
If you don't want a call to be optimized away, call your
own function in another translation unit.
>
No.
>
There are several ways that guarantee your code will carry out the
writes here (though none that guarantee the secret data is not also
stored elsewhere).  Using a function in a different TU is not one of
these techniques.  You do people a disfavour by recommending it.

It demonstrably is.

(And don't turn
on nonconforming cross-translation-unit optimizations.)
 
>
If I knew of any non-conforming cross-translation-unit optimisations in
a compiler, I would avoid using them until the compiler vendor had fixed
the bug in question.

They are not fixable. Translation units are separate, subject
to separate semantic analysis, which is settled prior to linkage.

The semantic analysis of one translation unit must be carried out in the
absence of any information about what is in another translation unit.

--
TXR Programming Language: http://nongnu.org/txr
Cygnal: Cygwin Native Application Library: http://kylheku.com/cygnal
Mastodon: @Kazinator@mstdn.ca

Date Sujet#  Auteur
20 Mar 24 * A Famous Security Bug118Stefan Ram
20 Mar 24 +* Re: A Famous Security Bug108Kaz Kylheku
20 Mar 24 i+* Re: A Famous Security Bug2Keith Thompson
20 Mar 24 ii`- Re: A Famous Security Bug1Keith Thompson
21 Mar 24 i+* Re: A Famous Security Bug35David Brown
21 Mar 24 ii`* Re: A Famous Security Bug34Kaz Kylheku
21 Mar 24 ii +* Re: A Famous Security Bug4Chris M. Thomasson
21 Mar 24 ii i`* Re: A Famous Security Bug3Chris M. Thomasson
22 Mar 24 ii i `* Re: A Famous Security Bug2Chris M. Thomasson
22 Mar 24 ii i  `- Re: A Famous Security Bug1Chris M. Thomasson
21 Mar 24 ii +* Re: A Famous Security Bug28Keith Thompson
22 Mar 24 ii i+* Re: A Famous Security Bug24Kaz Kylheku
22 Mar 24 ii ii+* Re: A Famous Security Bug19Keith Thompson
22 Mar 24 ii iii`* Re: A Famous Security Bug18Kaz Kylheku
22 Mar 24 ii iii +* Re: A Famous Security Bug2James Kuyper
22 Mar 24 ii iii i`- Re: A Famous Security Bug1Kaz Kylheku
22 Mar 24 ii iii +- Re: A Famous Security Bug1David Brown
22 Mar 24 ii iii `* Re: A Famous Security Bug14Keith Thompson
22 Mar 24 ii iii  `* Re: A Famous Security Bug13Kaz Kylheku
23 Mar 24 ii iii   `* Re: A Famous Security Bug12David Brown
23 Mar 24 ii iii    `* Re: A Famous Security Bug11Kaz Kylheku
23 Mar 24 ii iii     +* Re: A Famous Security Bug2David Brown
24 Mar 24 ii iii     i`- Re: A Famous Security Bug1Kaz Kylheku
23 Mar 24 ii iii     `* Re: A Famous Security Bug8James Kuyper
24 Mar 24 ii iii      `* Re: A Famous Security Bug7Kaz Kylheku
24 Mar 24 ii iii       `* Re: A Famous Security Bug6David Brown
24 Mar 24 ii iii        `* Re: A Famous Security Bug5Kaz Kylheku
24 Mar 24 ii iii         +* Re: A Famous Security Bug3David Brown
27 Mar 24 ii iii         i`* Re: A Famous Security Bug2Kaz Kylheku
28 Mar 24 ii iii         i `- Re: A Famous Security Bug1David Brown
24 Mar 24 ii iii         `- Re: A Famous Security Bug1Chris M. Thomasson
22 Mar 24 ii ii+- Re: A Famous Security Bug1James Kuyper
22 Mar 24 ii ii`* Re: A Famous Security Bug3David Brown
22 Mar 24 ii ii `* Re: A Famous Security Bug2Kaz Kylheku
22 Mar 24 ii ii  `- Re: A Famous Security Bug1David Brown
22 Mar 24 ii i`* Re: A Famous Security Bug3James Kuyper
22 Mar 24 ii i `* Re: A Famous Security Bug2Kaz Kylheku
22 Mar 24 ii i  `- Re: A Famous Security Bug1James Kuyper
22 Mar 24 ii `- Re: A Famous Security Bug1David Brown
21 Mar 24 i`* Re: A Famous Security Bug70Anton Shepelev
21 Mar 24 i +- Re: A Famous Security Bug1Keith Thompson
21 Mar 24 i +* Re: A Famous Security Bug15Kaz Kylheku
22 Mar 24 i i+* Re: A Famous Security Bug13David Brown
22 Mar 24 i ii`* Re: A Famous Security Bug12Kaz Kylheku
22 Mar 24 i ii +- Re: A Famous Security Bug1James Kuyper
22 Mar 24 i ii `* Re: A Famous Security Bug10David Brown
23 Mar 24 i ii  `* Re: A Famous Security Bug9Richard Kettlewell
23 Mar 24 i ii   +- Re: A Famous Security Bug1Kaz Kylheku
23 Mar 24 i ii   +* Re: A Famous Security Bug2David Brown
23 Mar 24 i ii   i`- Re: A Famous Security Bug1Kaz Kylheku
24 Mar 24 i ii   `* Re: A Famous Security Bug5Tim Rentsch
24 Mar 24 i ii    `* Re: A Famous Security Bug4Malcolm McLean
17 Apr 24 i ii     `* Re: A Famous Security Bug3Tim Rentsch
18 Apr 24 i ii      +- Re: A Famous Security Bug1David Brown
18 Apr 24 i ii      `- Re: A Famous Security Bug1Keith Thompson
28 Mar 24 i i`- Re: A Famous Security Bug1Anton Shepelev
22 Mar 24 i +- Re: A Famous Security Bug1Tim Rentsch
22 Mar 24 i `* Re: A Famous Security Bug52James Kuyper
22 Mar 24 i  `* Re: A Famous Security Bug51bart
23 Mar 24 i   +* Re: A Famous Security Bug5Keith Thompson
23 Mar 24 i   i`* Re: A Famous Security Bug4Kaz Kylheku
23 Mar 24 i   i `* Re: A Famous Security Bug3David Brown
23 Mar 24 i   i  `* Re: A Famous Security Bug2bart
24 Mar 24 i   i   `- Re: A Famous Security Bug1David Brown
23 Mar 24 i   `* Re: A Famous Security Bug45James Kuyper
23 Mar 24 i    `* Re: A Famous Security Bug44bart
23 Mar 24 i     +* Re: A Famous Security Bug37David Brown
23 Mar 24 i     i`* Re: A Famous Security Bug36bart
24 Mar 24 i     i +* Re: A Famous Security Bug29David Brown
24 Mar 24 i     i i`* Re: A Famous Security Bug28bart
24 Mar 24 i     i i +* Re: A Famous Security Bug12Keith Thompson
25 Mar 24 i     i i i+- Re: A Famous Security Bug1David Brown
25 Mar 24 i     i i i+* Re: A Famous Security Bug3Michael S
25 Mar 24 i     i i ii+- Re: A Famous Security Bug1David Brown
25 Mar 24 i     i i ii`- Re: A Famous Security Bug1Keith Thompson
25 Mar 24 i     i i i`* Re: A Famous Security Bug7bart
25 Mar 24 i     i i i `* Re: A Famous Security Bug6Michael S
25 Mar 24 i     i i i  +* Re: A Famous Security Bug4bart
25 Mar 24 i     i i i  i`* Re: A Famous Security Bug3David Brown
25 Mar 24 i     i i i  i `* Re: A Famous Security Bug2Malcolm McLean
25 Mar 24 i     i i i  i  `- Re: A Famous Security Bug1Michael S
25 Mar 24 i     i i i  `- Re: A Famous Security Bug1David Brown
25 Mar 24 i     i i `* Re: A Famous Security Bug15David Brown
25 Mar 24 i     i i  `* Re: A Famous Security Bug14Michael S
25 Mar 24 i     i i   `* Re: A Famous Security Bug13David Brown
25 Mar 24 i     i i    +* Re: A Famous Security Bug3Michael S
25 Mar 24 i     i i    i+- Re: A Famous Security Bug1David Brown
25 Mar 24 i     i i    i`- Re: A Famous Security Bug1bart
25 Mar 24 i     i i    `* Re: A Famous Security Bug9bart
25 Mar 24 i     i i     +* Re: A Famous Security Bug7Michael S
25 Mar 24 i     i i     i`* Re: A Famous Security Bug6bart
25 Mar 24 i     i i     i +- Re: A Famous Security Bug1David Brown
25 Mar 24 i     i i     i `* Re: A Famous Security Bug4Michael S
25 Mar 24 i     i i     i  `* Re: A Famous Security Bug3bart
26 Mar 24 i     i i     i   `* Re: A Famous Security Bug2Michael S
26 Mar 24 i     i i     i    `- Re: A Famous Security Bug1bart
25 Mar 24 i     i i     `- Re: A Famous Security Bug1David Brown
24 Mar 24 i     i `* Re: A Famous Security Bug6Michael S
24 Mar 24 i     i  `* Re: A Famous Security Bug5bart
25 Mar 24 i     i   +* Re: A Famous Security Bug2Michael S
25 Mar 24 i     i   i`- Re: A Famous Security Bug1Michael S
25 Mar 24 i     i   +- Re: A Famous Security Bug1David Brown
28 Mar 24 i     i   `- Re: A Famous Security Bug1James Kuyper
23 Mar 24 i     +- Re: A Famous Security Bug1Tim Rentsch
24 Mar 24 i     +- Re: A Famous Security Bug1Michael S
24 Mar 24 i     +* Re: A Famous Security Bug3Michael S
28 Mar 24 i     `- Re: A Famous Security Bug1James Kuyper
20 Mar 24 +- Re: A Famous Security Bug1Joerg Mertens
20 Mar 24 +* Re: A Famous Security Bug5Chris M. Thomasson
27 Mar 24 `* Re: A Famous Security Bug3Stefan Ram

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