Re: [PATCH v3 0/3] x86/fpu: prevent leaking FPU registers via invalid FPU state

Ingo Molnar
2017-09-22T05:33:19Z

* Eric Biggers <ebiggers3@gmail.com> wrote:

> From: Eric Biggers <ebiggers@google.com>
>
> This series fixes the bug found by syzkaller where the ptrace syscall
> can be used to set invalid bits in a task's FPU state. I also found
> that an equivalent bug was reachable using the sigreturn syscall, so the
> first patch fixes the bug in both cases.
>
> The other two patches start validating the other parts of the
> xstate_header and make it so that invalid FPU states can no longer be
> abused to leak the FPU registers of other processes.
>
> Changes since v2:
> - Use an exception handler to handle invalid FPU states
> (suggested by Andy Lutomirski)
> - Check the size of xstate_header.reserved at build time
> (suggested by Dave Hansen)
>
> Eric Biggers (3):
> x86/fpu: don't let userspace set bogus xcomp_bv
> x86/fpu: tighten validation of user-supplied xstate_header
> x86/fpu: reinitialize FPU registers if restoring FPU state fails
>
> arch/x86/include/asm/fpu/internal.h | 51 +++++++++++--------------------------
> arch/x86/include/asm/fpu/xstate.h | 25 ++++++++++++++++++
> arch/x86/kernel/fpu/regset.c | 20 +++++++--------
> arch/x86/kernel/fpu/signal.c | 15 ++++++++---
> arch/x86/kernel/fpu/xstate.c | 27 ++++++++------------
> arch/x86/mm/extable.c | 24 +++++++++++++++++
> 6 files changed, 94 insertions(+), 68 deletions(-)

Ok - could you please rebase these to to tip:master that is at:

git git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git master

In particular this has a WIP.x86/fpu branch with FPU fixes+changes queued up but
not merged upstream (yet), which conflict with these changes. I'd like to merge
them all together.

Thanks,

Ingo