Re: [PATCH] x86/fpu/xstate: Clear uninitialized xstate areas in core dump

[Sebastian Andrzej Siewior]

On 2020-05-07 09:49:04 [-0700], Yu-cheng Yu wrote:
> In a core dump, copy_xstate_to_kernel() copies only enabled user xfeatures
> to a kernel buffer without touching areas for disabled xfeatures.  However,
> those uninitialized areas may contain random data, which is then written to
> the core dump file and can be read by a non-privileged user.
> 
> Fix it by clearing uninitialized areas.

Is the problem that copy_xstate_to_kernel() gets `kbuf' passed which
isn't zeroed? If so, would it work clean that upfront?

Sebastian