Messages in this thread | | | From | Andrew Lutomirski <> | Date | Wed, 1 Jun 2011 08:36:20 -0400 | Subject | Re: [PATCH v3 08/10] x86-64: Emulate legacy vsyscalls |
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On Wed, Jun 1, 2011 at 7:54 AM, Brian Gerst <brgerst@gmail.com> wrote: > On Tue, May 31, 2011 at 9:16 AM, Andy Lutomirski <luto@mit.edu> wrote: >> There's a fair amount of code in the vsyscall page. It contains a >> syscall instruction (in the gettimeofday fallback) and who knows >> what will happen if an exploit jumps into the middle of some other >> code. >> >> Reduce the risk by replacing the vsyscalls with short magic >> incantations that cause the kernel to emulate the real vsyscalls. >> These incantations are useless if entered in the middle. > > How about remapping the vsyscall page into a random page in the > modules area, and make the fixed page simply have stubs that jump to > the code in that page. That would solve the fixed address syscall > problem without any more overhead.
It wouldn't give any protection against local attacks, though.
--Andy
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