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SubjectRe: [PATCH v4 0/3] x86/fpu: prevent leaking FPU registers via invalid FPU state

* 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 v3:
> - Rebase onto tip/master
>
> 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 | 17 +++++-------
> arch/x86/kernel/fpu/signal.c | 18 ++++++++-----
> arch/x86/kernel/fpu/xstate.c | 52 ++++++++++++++-----------------------
> arch/x86/mm/extable.c | 24 +++++++++++++++++
> 6 files changed, 102 insertions(+), 85 deletions(-)

Thank you Eric - I've applied them and will push it all out together with the
other pending bits in WIP.x86/fpu.

Ingo

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