From: "Андрей Аладьев" <aladjev.andrew@gmail.com>
To: musl@lists.openwall.com
Subject: Re: [musl] Static linking is broken after creation of DT_TEXTREL segment
Date: Fri, 31 Jan 2020 22:11:21 +0300 [thread overview]
Message-ID: <CAMw0sz+4TgZo+KHC3HVmx3+M=c_4siSpe3auxqZPoVj6TKmgig@mail.gmail.com> (raw)
In-Reply-To: <20200131180109.GJ1663@brightrain.aerifal.cx>
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Now everything is clear, thank you. Have a good weekend =)
пт, 31 янв. 2020 г. в 21:01, Rich Felker <dalias@libc.org>:
> On Fri, Jan 31, 2020 at 08:51:05PM +0300, Андрей Аладьев wrote:
> > > Moreover, adding such a thing is not desirable because it adds a
> > linear-search of an array of load segments to each relocation
> >
> > I think it is possible to make this search O(log n).
>
> This would help if n were large, but in practice it's very small (2-3
> or maybe 4) and the cost is just the code path overhead, which gets
> worse if you do that, not the largeness of n.
>
> > for (j=0; v-p->loadmap->segs[j].p_vaddr >= p->loadmap->segs[j].p_memsz;
> > j++);
> >
> > This code takes first segment that can handle address. It looks possible
> to
> > create modified list of virtual segments, that won't overlap and make a
> > binary search.
>
> They're non-overlapping anyway but not necessarily sorted, and can't
> be simultaneously sorted by addr and p_vaddr since the orders will
> differ.
>
> > > This is not a reasonable tradeoff and it's why I proposed the "hull"
> > approach
> >
> > It may not be safe from maintainability perspective. Library will be
> > changed, everybody will forget what part of code was protected by
> external
> > validation and it will provide unexpected behaviour. Please consider
> double
> > validation approach:
>
> You're really not making sense here. What does "protected by external
> validation" mean? There is presently nothing being "protected" here;
> the discussion is just about more informative errors. If this is used
> as a boundary for some sort of safety at some point in the future (as
> mentioned before, the benefit of this is probably limited to ldd and
> thus not very useful) then it will be done according to constraints
> needed to achieve that.
>
> > external validation in production and debug only mode
> > with loadmap like validation.
>
> We do not have separate "production" and "debug" modes. This kind of
> thing (combinatoric build-time options) is what lacks maintainability.
>
> Rich
>
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next prev parent reply other threads:[~2020-01-31 19:11 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-29 18:41 Андрей Аладьев
2020-01-29 19:19 ` Markus Wichmann
2020-01-29 19:38 ` Markus Wichmann
2020-01-29 20:48 ` Rich Felker
2020-01-29 20:08 ` Андрей Аладьев
2020-01-30 17:02 ` Markus Wichmann
2020-01-31 4:24 ` Rich Felker
2020-01-31 14:47 ` Markus Wichmann
2020-01-31 16:35 ` Rich Felker
2020-01-31 15:16 ` Андрей Аладьев
2020-01-31 16:40 ` Rich Felker
2020-01-31 17:51 ` Андрей Аладьев
2020-01-31 18:01 ` Rich Felker
2020-01-31 19:11 ` Андрей Аладьев [this message]
2020-02-03 3:10 ` Rich Felker
2020-02-03 4:05 ` Rich Felker
2020-02-03 4:32 ` Markus Wichmann
2020-02-03 4:40 ` Rich Felker
2020-01-29 20:53 ` Rich Felker
2020-01-29 21:10 ` Szabolcs Nagy
2020-01-29 21:35 ` Андрей Аладьев
2020-01-29 21:46 ` Rich Felker
2020-01-29 23:10 ` Андрей Аладьев
2020-01-29 23:20 ` Szabolcs Nagy
2020-01-29 21:14 ` Андрей Аладьев
2020-01-29 21:43 ` Rich Felker
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