Messages in this thread | | | Date | Mon, 30 May 2011 12:59:37 +0200 | From | Ingo Molnar <> | Subject | Re: [PATCH v2 08/10] x86-64: Emulate vsyscalls |
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* Andrew Lutomirski <luto@mit.edu> wrote:
> On Mon, May 30, 2011 at 3:46 AM, Ingo Molnar <mingo@elte.hu> wrote: > > > > * Andy Lutomirski <luto@MIT.EDU> wrote: > > > >> There's a fair amount of code in the vsyscall page, and who knows > >> what will happen if an exploit jumps into the middle of it. Reduce > >> the risk by replacing most of it with short magic incantations that > >> are useless if entered in the middle. This change can be disabled > >> by CONFIG_UNSAFE_VSYSCALLS (default y). > > > > btw., please flip the default or consider removing the option > > altogether. > > > > We want to improve security and we want safe vsyscalls the default, > > and it's no good if we make it too easy for users to keep the fire > > door open all the time! :-) > > I'd advocate waiting until glibc 2.14 comes out with this change: > > http://sourceware.org/git/?p=glibc.git;a=commit;h=a8509ca540427502bd955f35296ff7b727c7a8a1 > > I want to add a warning (ratelimited to an extremely low rate) in v3 > whenever any of the vsyscalls get used telling users that their legacy > code is suffering a performance impact, but it seems like bad form to > tell people to build glibc from git to avoid a regression.
But only statically built binaries would be impacted in practice, right? The number of statically built binaries that heavily rely on vsyscalls ought to be a very small set ...
Thanks,
Ingo -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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