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Re: [RFC PATCH 0/5] arm64: Signal context expansion


On 09/09/2016 04:15 PM, Dave Martin wrote:
This new record can be added in sigframe.__reserved[] if there is a
need to allocate extra space beyond the standard signal frame.  The
extra block of memory referenced by extra_context can then be parsed in
the same way as sigcontext.__reserved[].  Old code should just ignore
the whole thing as an unrecognised record.  To maintain backward
compatibility, signal context records defined today are always placed
directly in __reserved[], never in the block referenced by
extra_context.

Do you add this extra information only if the stack is sufficiently large?

x86_64 adds the new information even for small stacks set up with sigaltstack, leading to memory corruption on bleeding-edge hardware:

  <https://bugzilla.kernel.org/show_bug.cgi?id=153531>

Thanks,
Florian


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