Messages in this thread | | | Date | Tue, 31 May 2011 20:57:27 +0200 (CEST) | From | Thomas Gleixner <> | Subject | Re: [PATCH v4 10/10] x86-64: Add CONFIG_UNSAFE_VSYSCALLS to feature-removal-schedule |
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On Tue, 31 May 2011, Andi Kleen wrote: > > +What: CONFIG_UNSAFE_VSYSCALLS (x86_64) > > +When: When glibc 2.14 or newer is ubitquitous. Perhaps mid-2012. > > +Why: Having user-executable code at a fixed address is a security problem. > > + Turning off CONFIG_UNSAFE_VSYSCALLS mostly removes the risk but will > > + make the time() function slower on glibc versions 2.13 and below. > > I disagree with this description (and the whole idea really) > > First it's time+gettimeofday+vgetcu, not just time. > > A more accurate description is > > "will make all x86-64 Linux programs written to the original pre > vDSO syscall ABI significantly slower" > > And the assumption that all world is using glibc is still as bad > as it was on the first po.st > > And it's still a bad idea. Especially since there's a much better > alternative anyways for the "security problem" which has none of > these drawbacks.
How about posting an alternative patch?
Thanks,
tglx
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