In preparation for FORTIFY_SOURCE performing compile-time and run-time field bounds checking for memset(), avoid intentionally writing across neighboring fields.
Add struct_group() to mark region of struct x86_emulate_ctxt that should be initialized to zero.
Signed-off-by: Kees Cook keescook@chromium.org --- arch/x86/kvm/emulate.c | 3 +-- arch/x86/kvm/kvm_emulate.h | 19 +++++++++++-------- 2 files changed, 12 insertions(+), 10 deletions(-)
diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c index 2837110e66ed..2608a047e769 100644 --- a/arch/x86/kvm/emulate.c +++ b/arch/x86/kvm/emulate.c @@ -5377,8 +5377,7 @@ static int fastop(struct x86_emulate_ctxt *ctxt, fastop_t fop)
void init_decode_cache(struct x86_emulate_ctxt *ctxt) { - memset(&ctxt->rip_relative, 0, - (void *)&ctxt->modrm - (void *)&ctxt->rip_relative); + memset(&ctxt->decode_cache, 0, sizeof(ctxt->decode_cache));
ctxt->io_read.pos = 0; ctxt->io_read.end = 0; diff --git a/arch/x86/kvm/kvm_emulate.h b/arch/x86/kvm/kvm_emulate.h index 68b420289d7e..9b8afcb8ad39 100644 --- a/arch/x86/kvm/kvm_emulate.h +++ b/arch/x86/kvm/kvm_emulate.h @@ -341,14 +341,17 @@ struct x86_emulate_ctxt { * the rest are initialized unconditionally in x86_decode_insn * or elsewhere */ - bool rip_relative; - u8 rex_prefix; - u8 lock_prefix; - u8 rep_prefix; - /* bitmaps of registers in _regs[] that can be read */ - u32 regs_valid; - /* bitmaps of registers in _regs[] that have been written */ - u32 regs_dirty; + struct_group(decode_cache, + bool rip_relative; + u8 rex_prefix; + u8 lock_prefix; + u8 rep_prefix; + /* bitmaps of registers in _regs[] that can be read */ + u32 regs_valid; + /* bitmaps of registers in _regs[] that have been written */ + u32 regs_dirty; + ); + /* modrm */ u8 modrm; u8 modrm_mod;