On Tue, Dec 22, 2020 at 05:53:11PM -0800, Chang S. Bae wrote:

The kernel pushes data on the userspace stack when entering a signal. If
using a sigaltstack(), the kernel precisely knows the user stack size.

^^^^^^^^^^^^^^^^^^^^^^^

Formulate properly.

When the kernel knows that the user stack is too small, avoid the overflow
and do an immediate SIGSEGV instead.

      ^^^^^^^^^^^^^^^^^^^^^^^

Ditto.

This overflow is known to occur on systems with large XSAVE state. The
effort to increase the size typically used for altstacks reduces the

						^^^^^^^^^^

"alternate signal stacks"

-- 
Regards/Gruss,
    Boris.

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