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| From | Ian Collins <ian-news@hotmail.com> |
|---|---|
| Newsgroups | comp.lang.c |
| Subject | Re: Is it possible C is the security problem? |
| Date | 2015-11-20 12:20 +1300 |
| Message-ID | <db73qbFjpqnU3@mid.individual.net> (permalink) |
| References | (18 earlier) <ca1c4e83-549d-4434-9e1c-8189e8b208b5@googlegroups.com> <db5a4nF2f99U3@mid.individual.net> <5a28d00d-e875-44bf-aa4c-3b1b7307d083@googlegroups.com> <db5e6rF2f99U4@mid.individual.net> <b8141646-a457-4238-9ce0-6fa4a076e163@googlegroups.com> |
supercat@casperkitty.com wrote:
> On Thursday, November 19, 2015 at 2:06:04 AM UTC-6, Ian Collins wrote:
>> How could it? There's no way of knowing that free64 isn't going to
>> access the data passed to it.
>
> Perhaps it can see into the implementation:
>
> void *next_alloc64;
> void *alloc64(void)
> {
> void *temp = next_alloc64;
> next_alloc64 = *(void**)temp;
> return temp;
> }
> void free64(void *p)
> {
> *(void**)p = next_alloc64;
> next_alloc64 = p;
> }
>
> If code has some outside means of ensuring that the number of block requests
> minus releases won't exceed the number of blocks allocated at startup, the
> above is all that would be necessary for the allocate/release functions. A
> lot faster than malloc/free, since there's no need to search nor consolidate
> free blocks. Otherwise code would have to add a counter to the mix. Still
> easily small enough to in-line the common cases, though.
Given this assumption, gcc will reorder the code in a similar way to the
code you just snipped, whether C89 or C99 is selected. So either one of
us or the compiler writers are missing something.
>>> Until fairly recently, code like the above was 100% reliable on most systems
>>> and, as noted, vastly more efficient than any alternative permitted by the
>>> Standard. Alas, some compiler writers see no reason it should be supported.
>>
>> Was it?
>
> Yes. On a compiler which promises suitable memory semantics the code would
> be 100% reliable (assuming I typed it right) and way faster than malloc/free.
> Look into published embedded operating systems and one will find a lot of
> that sort of thing. Can you offer any way to achieve equivalent functionality
> and performance without violating C's typing rules?
I've written more than my share of embedded allocators... I must admit
I probably wasn't to bothered with the finer points of the C aliasing
rules, just that the code did the right thing!
--
Ian Collins
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Is it possible C is the security problem? G G <gdotone@gmail.com> - 2015-11-03 06:31 -0800
Re: Is it possible C is the security problem? Richard Heathfield <rjh@cpax.org.uk> - 2015-11-03 14:57 +0000
Re: Is it possible C is the security problem? Jorgen Grahn <grahn+nntp@snipabacken.se> - 2015-11-03 15:04 +0000
Re: Is it possible C is the security problem? G G <gdotone@gmail.com> - 2015-11-03 07:11 -0800
Re: Is it possible C is the security problem? Richard Heathfield <rjh@cpax.org.uk> - 2015-11-03 15:25 +0000
Re: Is it possible C is the security problem? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-11-03 20:13 +0000
Re: Is it possible C is the security problem? Eric Sosman <esosman@comcast-dot-net.invalid> - 2015-11-03 15:18 -0500
Re: Is it possible C is the security problem? Richard Heathfield <rjh@cpax.org.uk> - 2015-11-03 20:34 +0000
Re: Is it possible C is the security problem? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-11-03 22:47 +0000
Re: Is it possible C is the security problem? Udyant Wig <udyantw@gmail.com> - 2015-11-04 15:36 +0530
Re: Is it possible C is the security problem? Richard Heathfield <rjh@cpax.org.uk> - 2015-11-04 10:34 +0000
Re: Is it possible C is the security problem? supercat@casperkitty.com - 2015-11-03 15:18 -0800
Re: Is it possible C is the security problem? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-11-03 17:42 -0800
Re: Is it possible C is the security problem? Geoff <geoff@invalid.invalid> - 2015-11-03 15:32 -0800
Re: Is it possible C is the security problem? Richard Heathfield <rjh@cpax.org.uk> - 2015-11-03 23:57 +0000
Re: Is it possible C is the security problem? Geoff <geoff@invalid.invalid> - 2015-11-03 21:13 -0800
Re: Is it possible C is the security problem? Richard Heathfield <rjh@cpax.org.uk> - 2015-11-04 07:22 +0000
Re: Is it possible C is the security problem? David Brown <david.brown@hesbynett.no> - 2015-11-04 11:32 +0100
Re: Is it possible C is the security problem? Richard Heathfield <rjh@cpax.org.uk> - 2015-11-04 10:54 +0000
Re: Is it possible C is the security problem? David Brown <david.brown@hesbynett.no> - 2015-11-04 13:38 +0100
Re: Is it possible C is the security problem? Jorgen Grahn <grahn+nntp@snipabacken.se> - 2015-11-07 08:27 +0000
Re: Is it possible C is the security problem? Jorgen Grahn <grahn+nntp@snipabacken.se> - 2015-11-05 09:26 +0000
Re: Is it possible C is the security problem? Richard Heathfield <rjh@cpax.org.uk> - 2015-11-05 10:03 +0000
Re: Is it possible C is the security problem? James Kuyper <jameskuyper@verizon.net> - 2015-11-05 08:53 -0500
Re: Is it possible C is the security problem? Jorgen Grahn <grahn+nntp@snipabacken.se> - 2015-11-06 10:04 +0000
Re: Is it possible C is the security problem? Reinhardt Behm <rbehm@hushmail.com> - 2015-11-05 21:06 +0800
Re: Is it possible C is the security problem? Keith Thompson <kst-u@mib.org> - 2015-11-05 11:14 -0800
Re: Is it possible C is the security problem? supercat@casperkitty.com - 2015-11-05 11:44 -0800
Re: Is it possible C is the security problem? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-11-07 02:43 -0800
Re: Is it possible C is the security problem? supercat@casperkitty.com - 2015-11-07 17:30 -0800
Re: Is it possible C is the security problem? raltbos@xs4all.nl (Richard Bos) - 2015-11-10 16:35 +0000
Re: Is it possible C is the security problem? Eric Sosman <esosman@comcast-dot-net.invalid> - 2015-11-10 11:52 -0500
Re: Is it possible C is the security problem? Robert Wessel <robertwessel2@yahoo.com> - 2015-11-11 00:48 -0600
Re: Is it possible C is the security problem? raltbos@xs4all.nl (Richard Bos) - 2015-11-17 21:55 +0000
Re: Is it possible C is the security problem? Robert Wessel <robertwessel2@yahoo.com> - 2015-11-17 19:14 -0600
Re: Is it possible C is the security problem? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-11-18 03:40 +0000
Re: Is it possible C is the security problem? Robert Wessel <robertwessel2@yahoo.com> - 2015-11-17 23:01 -0600
Re: Is it possible C is the security problem? Keith Thompson <kst-u@mib.org> - 2015-11-18 09:00 -0800
Re: Is it possible C is the security problem? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-11-18 09:09 -0800
Re: Is it possible C is the security problem? Robert Wessel <robertwessel2@yahoo.com> - 2015-11-18 15:35 -0600
Re: Is it possible C is the security problem? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-11-18 21:35 +0000
Re: Is it possible C is the security problem? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-11-18 20:38 -0800
Re: Is it possible C is the security problem? Richard Heathfield <rjh@cpax.org.uk> - 2015-11-19 05:40 +0000
Re: Is it possible C is the security problem? supercat@casperkitty.com - 2015-11-18 22:55 -0800
Re: Is it possible C is the security problem? Ian Collins <ian-news@hotmail.com> - 2015-11-19 19:56 +1300
Re: Is it possible C is the security problem? supercat@casperkitty.com - 2015-11-18 23:40 -0800
Re: Is it possible C is the security problem? Ian Collins <ian-news@hotmail.com> - 2015-11-19 21:05 +1300
Re: Is it possible C is the security problem? supercat@casperkitty.com - 2015-11-19 06:40 -0800
Re: Is it possible C is the security problem? asetofsymbols@gmail.com - 2015-11-19 11:37 -0800
Re: Is it possible C is the security problem? asetofsymbols@gmail.com - 2015-11-19 12:09 -0800
Re: Is it possible C is the security problem? supercat@casperkitty.com - 2015-11-19 12:52 -0800
Re: Is it possible C is the security problem? Ian Collins <ian-news@hotmail.com> - 2015-11-20 12:20 +1300
Re: Is it possible C is the security problem? supercat@casperkitty.com - 2015-11-19 15:34 -0800
Re: Is it possible C is the security problem? Ian Collins <ian-news@hotmail.com> - 2015-11-22 16:43 +1300
Re: Is it possible C is the security problem? supercat@casperkitty.com - 2015-11-21 21:28 -0800
Re: Is it possible C is the security problem? Ian Collins <ian-news@hotmail.com> - 2015-11-22 20:51 +1300
Re: Is it possible C is the security problem? supercat@casperkitty.com - 2015-11-22 07:26 -0800
Re: Is it possible C is the security problem? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-11-22 09:42 -0800
Re: Is it possible C is the security problem? supercat@casperkitty.com - 2015-11-22 09:59 -0800
Re: Is it possible C is the security problem? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-11-23 07:08 +0000
Re: Is it possible C is the security problem? Ian Collins <ian-news@hotmail.com> - 2015-11-23 11:57 +1300
Re: Is it possible C is the security problem? supercat@casperkitty.com - 2015-11-22 16:06 -0800
Re: Is it possible C is the security problem? Ian Collins <ian-news@hotmail.com> - 2015-11-23 13:26 +1300
Re: Is it possible C is the security problem? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-11-19 09:09 +0000
Re: Is it possible C is the security problem? Keith Thompson <kst-u@mib.org> - 2015-11-20 02:29 -0800
Re: Is it possible C is the security problem? raltbos@xs4all.nl (Richard Bos) - 2015-11-20 12:33 +0000
Re: Is it possible C is the security problem? supercat@casperkitty.com - 2015-11-20 09:26 -0800
Re: Is it possible C is the security problem? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-11-19 13:37 +0000
Re: Is it possible C is the security problem? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-11-19 14:07 -0800
Re: Is it possible C is the security problem? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-11-20 01:38 +0000
Re: Is it possible C is the security problem? supercat@casperkitty.com - 2015-11-19 18:43 -0800
Re: Is it possible C is the security problem? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-11-20 12:09 +0000
Re: Is it possible C is the security problem? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-11-20 01:48 -0800
Re: Is it possible C is the security problem? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-11-20 11:16 +0000
Re: Is it possible C is the security problem? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-11-20 05:04 -0800
Re: Is it possible C is the security problem? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-11-20 18:18 +0000
Re: Is it possible C is the security problem? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-11-20 11:55 -0800
Re: Is it possible C is the security problem? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-11-21 00:27 +0000
Re: Is it possible C is the security problem? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-11-20 18:57 -0800
Re: Is it possible C is the security problem? Keith Thompson <kst-u@mib.org> - 2015-11-20 19:50 -0800
Re: Is it possible C is the security problem? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-11-20 20:06 -0800
Re: Is it possible C is the security problem? Keith Thompson <kst-u@mib.org> - 2015-11-20 20:46 -0800
Re: Is it possible C is the security problem? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-11-20 20:56 -0800
Re: Is it possible C is the security problem? Robert Wessel <robertwessel2@yahoo.com> - 2015-11-21 04:58 -0600
Re: Is it possible C is the security problem? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-11-21 04:59 -0800
Re: Is it possible C is the security problem? Robert Wessel <robertwessel2@yahoo.com> - 2015-11-21 13:26 -0600
Re: Is it possible C is the security problem? Eric Sosman <esosman@comcast-dot-net.invalid> - 2015-11-21 14:38 -0500
Re: Is it possible C is the security problem? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-11-21 06:49 +0000
Re: Is it possible C is the security problem? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-11-20 22:56 -0800
Re: Is it possible C is the security problem? Robert Wessel <robertwessel2@yahoo.com> - 2015-11-21 04:36 -0600
Re: Is it possible C is the security problem? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-11-21 06:44 +0000
Re: Is it possible C is the security problem? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-11-21 15:59 +0000
Re: Is it possible C is the security problem? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-11-21 18:33 +0000
Re: Is it possible C is the security problem? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-11-21 19:19 +0000
Re: Is it possible C is the security problem? Robert Wessel <robertwessel2@yahoo.com> - 2015-11-21 13:33 -0600
Re: Is it possible C is the security problem? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-11-22 14:42 +0000
Re: Is it possible C is the security problem? Tim Rentsch <txr@alumni.caltech.edu> - 2015-11-22 14:17 -0800
Re: Is it possible C is the security problem? Ian Collins <ian-news@hotmail.com> - 2015-11-20 14:51 +1300
Re: Is it possible C is the security problem? Robert Wessel <robertwessel2@yahoo.com> - 2015-11-19 08:06 -0600
Re: Is it possible C is the security problem? Robert Wessel <robertwessel2@yahoo.com> - 2015-11-18 15:40 -0600
Re: Is it possible C is the security problem? Tim Rentsch <txr@alumni.caltech.edu> - 2015-11-20 13:57 -0800
Re: Is it possible C is the security problem? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-11-21 06:56 +0000
Re: Is it possible C is the security problem? Tim Rentsch <txr@alumni.caltech.edu> - 2015-11-23 03:16 -0800
Re: Is it possible C is the security problem? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-11-23 22:28 +0000
Re: Is it possible C is the security problem? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-11-23 21:11 -0800
Re: Is it possible C is the security problem? Tim Rentsch <txr@alumni.caltech.edu> - 2015-11-24 10:29 -0800
Re: Is it possible C is the security problem? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-11-25 02:38 +0000
Re: Is it possible C is the security problem? Tim Rentsch <txr@alumni.caltech.edu> - 2015-11-27 13:54 -0800
Re: Is it possible C is the security problem? supercat@casperkitty.com - 2015-11-10 10:23 -0800
Re: Is it possible C is the security problem? Keith Thompson <kst-u@mib.org> - 2015-11-10 11:21 -0800
Re: Is it possible C is the security problem? Melzzzzz <mel@zzzzz.com> - 2015-11-04 00:58 +0100
Re: Is it possible C is the security problem? Les Cargill <lcargill99@comcast.com> - 2015-11-03 18:26 -0600
Re: Is it possible C is the security problem? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-11-04 02:06 +0000
Re: Is it possible C is the security problem? Ian Collins <ian-news@hotmail.com> - 2015-11-04 14:12 +1300
Re: Is it possible C is the security problem? Richard Heathfield <rjh@cpax.org.uk> - 2015-11-04 07:02 +0000
Re: Is it possible C is the security problem? Ian Collins <ian-news@hotmail.com> - 2015-11-04 20:42 +1300
Re: Is it possible C is the security problem? Richard Heathfield <rjh@cpax.org.uk> - 2015-11-04 08:06 +0000
Re: Is it possible C is the security problem? David Brown <david.brown@hesbynett.no> - 2015-11-04 11:25 +0100
Re: Is it possible C is the security problem? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-11-04 11:49 +0000
Re: Is it possible C is the security problem? David Brown <david.brown@hesbynett.no> - 2015-11-04 13:46 +0100
Re: Is it possible C is the security problem? raltbos@xs4all.nl (Richard Bos) - 2015-11-17 21:58 +0000
Re: Is it possible C is the security problem? David Brown <david.brown@hesbynett.no> - 2015-11-17 23:37 +0100
Re: Is it possible C is the security problem? David Thompson <dave.thompson2@verizon.net> - 2015-12-06 07:55 -0500
Re: Is it possible C is the security problem? Les Cargill <lcargill99@comcast.com> - 2015-12-06 14:23 -0600
Re: Is it possible C is the security problem? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-11-03 15:59 +0000
Re: Is it possible C is the security problem? Richard Heathfield <rjh@cpax.org.uk> - 2015-11-03 16:55 +0000
Re: Is it possible C is the security problem? see.my.homepage@gmail.com - 2015-11-04 02:29 -0800
Re: Is it possible C is the security problem? Richard Heathfield <rjh@cpax.org.uk> - 2015-11-04 10:48 +0000
Re: Is it possible C is the security problem? see.my.homepage@gmail.com - 2015-11-04 14:11 -0800
Re: Is it possible C is the security problem? Richard Heathfield <rjh@cpax.org.uk> - 2015-11-05 00:39 +0000
Re: Is it possible C is the security problem? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-11-05 01:15 +0000
Re: Is it possible C is the security problem? Richard Heathfield <rjh@cpax.org.uk> - 2015-11-05 02:02 +0000
Re: Is it possible C is the security problem? supercat@casperkitty.com - 2015-11-04 18:31 -0800
Re: Is it possible C is the security problem? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-11-05 12:38 +0000
Re: Is it possible C is the security problem? supercat@casperkitty.com - 2015-11-04 18:24 -0800
Re: Is it possible C is the security problem? Keith Thompson <kst-u@mib.org> - 2015-11-04 19:37 -0800
Re: Is it possible C is the security problem? David Brown <david.brown@hesbynett.no> - 2015-11-05 13:24 +0100
Re: Is it possible C is the security problem? supercat@casperkitty.com - 2015-11-05 06:47 -0800
Re: Is it possible C is the security problem? see.my.homepage@gmail.com - 2015-11-05 00:35 -0800
Re: Is it possible C is the security problem? Richard Heathfield <rjh@cpax.org.uk> - 2015-11-05 09:55 +0000
Re: Is it possible C is the security problem? see.my.homepage@gmail.com - 2015-11-05 05:02 -0800
Re: Is it possible C is the security problem? raltbos@xs4all.nl (Richard Bos) - 2015-11-06 10:18 +0000
Re: Is it possible C is the security problem? see.my.homepage@gmail.com - 2015-11-06 05:57 -0800
Re: Is it possible C is the security problem? James Kuyper <jameskuyper@verizon.net> - 2015-11-04 08:32 -0500
Re: Is it possible C is the security problem? Jorgen Grahn <grahn+nntp@snipabacken.se> - 2015-11-03 15:01 +0000
Re: Is it possible C is the security problem? Bartc <bc@freeuk.com> - 2015-11-03 15:10 +0000
Re: Is it possible C is the security problem? Eric Sosman <esosman@comcast-dot-net.invalid> - 2015-11-03 11:02 -0500
Re: Is it possible C is the security problem? Jorgen Grahn <grahn+nntp@snipabacken.se> - 2015-11-03 18:13 +0000
Re: Is it possible C is the security problem? Eric Sosman <esosman@comcast-dot-net.invalid> - 2015-11-03 15:16 -0500
Re: Is it possible C is the security problem? Jorgen Grahn <grahn+nntp@snipabacken.se> - 2015-11-04 09:38 +0000
Re: Is it possible C is the security problem? David Brown <david.brown@hesbynett.no> - 2015-11-04 11:38 +0100
Re: Is it possible C is the security problem? James Kuyper <jameskuyper@verizon.net> - 2015-11-03 11:58 -0500
Re: Is it possible C is the security problem? supercat@casperkitty.com - 2015-11-03 09:13 -0800
Re: Is it possible C is the security problem? gazelle@shell.xmission.com (Kenny McCormack) - 2015-11-03 18:08 +0000
Re: Is it possible C is the security problem? Nobody <nobody@nowhere.invalid> - 2015-11-04 04:49 +0000
Re: Is it possible C is the security problem? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-11-04 02:22 -0800
Re: Is it possible C is the security problem? gazelle@shell.xmission.com (Kenny McCormack) - 2015-11-04 13:28 +0000
Re: Is it possible C is the security problem? supercat@casperkitty.com - 2015-11-04 08:39 -0800
Re: Is it possible C is the security problem? John Bode <jfbode1029@gmail.com> - 2015-11-03 10:45 -0800
Re: Is it possible C is the security problem? supercat@casperkitty.com - 2015-11-03 11:05 -0800
Re: Is it possible C is the security problem? Les Cargill <lcargill99@comcast.com> - 2015-11-03 18:09 -0600
Is it possible C is the security problem? Chad <cdalten@gmail.com> - 2015-11-04 01:15 -0800
Re: Is it possible C is the security problem? gazelle@shell.xmission.com (Kenny McCormack) - 2015-11-04 13:31 +0000
Re: Is it possible C is the security problem? G G <gdotone@gmail.com> - 2015-11-18 10:55 -0800
Re: Is it possible C is the security problem? James Kuyper <jameskuyper@verizon.net> - 2015-11-18 14:05 -0500
Re: Is it possible C is the security problem? "D. Aaron Sawyer" <aaron@110.net> - 2015-11-18 19:47 -0500
Re: Is it possible C is the security problem? raltbos@xs4all.nl (Richard Bos) - 2015-11-20 10:43 +0000
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