Messages in this thread | | | From | "Reshetova, Elena" <> | Subject | RE: [PATCH] x86/entry/64: randomize kernel stack offset upon syscall | Date | Thu, 1 Aug 2019 06:35:47 +0000 |
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>> The in-stack randomization is really a very small change both code wise and >> logic wise. >> It does not affect real workloads and does not require enablement of other >> features (such as GCC plugins). >> So, I think we should really reconsider its inclusion.
>I'd agree: the code is tiny and while the benefit can't point to a >specific issue, it does point to the general weakness of the stack >offset being predictable which has been a core observation for many >stack-based attacks.
>If we're going to save state between syscalls (like the 4096 random >bytes pool), how about instead we just use a single per-CPU long mixed >with rdtsc saved at syscall exit. That should be a reasonable balance >between all the considerations and make it trivial for the feature to >be a boot flag without the extra page of storage, etc.
Sounds like a viable compromise for me. Ingo, Andy?
Best Regards, Elena.
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