Re: [PATCH v2 0/3] x86/fpu: prevent leaking FPU registers via invalid FPU state
From: Kees Cook
Date: Tue Sep 19 2017 - 23:03:11 EST
On Tue, Sep 19, 2017 at 5:44 PM, Eric Biggers <ebiggers3@xxxxxxxxx> wrote:
> From: Eric Biggers <ebiggers@xxxxxxxxxx>
> This is a second attempt to fix 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.
> 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
This series looks sensible to me! Thanks for getting this fixed up.
Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>
> arch/x86/include/asm/fpu/internal.h | 29 ++++++++++++++++++++---------
> arch/x86/include/asm/fpu/xstate.h | 19 +++++++++++++++++++
> arch/x86/kernel/fpu/core.c | 16 ++++++++++++++++
> arch/x86/kernel/fpu/regset.c | 20 +++++++++-----------
> arch/x86/kernel/fpu/signal.c | 15 +++++++++++----
> arch/x86/kernel/fpu/xstate.c | 27 ++++++++++-----------------
> 6 files changed, 85 insertions(+), 41 deletions(-)