Date: Sun, 27 Sep 2009 11:58:25 -0700 From: Julian Elischer <julian@elischer.org> To: Robert Watson <rwatson@FreeBSD.org> Cc: freebsd-current@freebsd.org, "Simon L. Nielsen" <simon@FreeBSD.org> Subject: Re: mmap zero mapping disallowed (Re: svn commit: r197537 - head/sys/vm]) Message-ID: <4ABFB5D1.4010408@elischer.org> In-Reply-To: <alpine.BSF.2.00.0909271733090.70406@fledge.watson.org> References: <20090927150233.GH1495@arthur.nitro.dk> <alpine.BSF.2.00.0909271733090.70406@fledge.watson.org>
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Robert Watson wrote: > > On Sun, 27 Sep 2009, Simon L. Nielsen wrote: > >> As mentioned in the commit message FreeBSD 9 / head now does not allow >> mmap'ing at zero by default, and this may break some apps. >> >> If anyone encounters applications which break because of this change, >> please let report it so we can see if it can be fixed. It might not >> be possible to fix some applications, but we at least would know which >> applications might need a special note in the documentation. > > There are probably some other ways to arrange mappings at 0x0, so we'll > need to dig through the system to identify them. To mind, the various > executable image activators are interesting (elf, a.out, etc), but we > should check other things that call VM insertion routines -- things like > the more interesting 3D device drivers. At the end of the day, this is > a mitigation technique, so if there are edge case non-default compiled > copmonents, etc, that's fine, but it would be nice to be thorough where > we can. > > While our automatic address selection code ever pick 0x0 as a mapping > address, btw? > > Robert N M Watson > Computer Laboratory > University of Cambridge > > >> What they need to do now is find a fault where the offset is > 4096.. I wouldn't bet against it..
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