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

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