Messages in this thread | | | From | Andrew Lutomirski <> | Date | Tue, 21 Feb 2012 11:29:00 -0800 | Subject | Re: [PATCH 30/30] x32: Add x32 VDSO support |
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On Tue, Feb 21, 2012 at 11:03 AM, H. Peter Anvin <hpa@zytor.com> wrote: > On 02/21/2012 10:54 AM, Andrew Lutomirski wrote: >> >> uclibc hardcodes a call to the vsyscall gettimeofday implementation in >> its locking primitives, which probably gives terrible performance, but >> that's a separate issue. I think do_emulate_vsyscall should send a >> segfault if called by an x32 task -- there's some security benefit to >> doing so, and there's unlikely to be any downside. >> > > The vsyscall page shouldn't be mapped for x32 tasks...
How is that possible? It lives in the fixmap and is presumably visible from any 64-bit code.
Admittedly, x32 tasks are probably somewhat difficult to trick into calling addresses with high bits set, but it's not necessarily impossible.
--Andy -- 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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