On Wed, Aug 18, 2021, Kees Cook wrote:
On Wed, Aug 18, 2021 at 03:11:28PM +0000, Sean Christopherson wrote:
From dbdca1f4cd01fee418c252e54c360d518b2b1ad6 Mon Sep 17 00:00:00 2001 From: Sean Christopherson seanjc@google.com Date: Wed, 18 Aug 2021 08:03:08 -0700 Subject: [PATCH] KVM: x86: Replace memset() "optimization" with normal per-field writes
Explicitly zero select fields in the emulator's decode cache instead of zeroing the fields via a gross memset() that spans six fields. gcc and clang are both clever enough to batch the first five fields into a single quadword MOV, i.e. memset() and individually zeroing generate identical code.
Removing the wart also prepares KVM for FORTIFY_SOURCE performing compile-time and run-time field bounds checking for memset().
No functional change intended.
Reported-by: Kees Cook keescook@chromium.org Signed-off-by: Sean Christopherson seanjc@google.com
Reviewed-by: Kees Cook keescook@chromium.org
Do you want me to take this patch into my tree, or do you want to carry it for KVM directly?
That's a Paolo question :-)
What's the expected timeframe for landing stricter bounds checking? If it's 5.16 or later, the easiest thing would be to squeak this into 5.15.