On 18/04/17 11:29, Jan Beulich wrote:
> The function is rather unlikely to be called for insns which don't have
> ModRM bytes, and hence addressing Coverity's recurring complaint of
> callers potentially consuming uninitialized data when they know that
> certain opcodes have ModRM bytes can be suppressed this way without
> unduly adding overhead to fast paths.
>
> Signed-off-by: Jan Beulich <jbeul...@suse.com>
Reviewed-by: Andrew Cooper <andrew.coop...@citrix.com>
>
> --- a/xen/arch/x86/x86_emulate/x86_emulate.c
> +++ b/xen/arch/x86/x86_emulate/x86_emulate.c
> @@ -8017,8 +8017,14 @@ x86_insn_modrm(const struct x86_emulate_
> {
> check_state(state);
>
> - if ( state->modrm_mod > 3 )
> + if ( unlikely(state->modrm_mod > 3) )
> + {
> + if ( rm )
> + *rm = ~0U;
> + if ( reg )
> + *reg = ~0U;
> return -EINVAL;
> + }
>
> if ( rm )
> *rm = state->modrm_rm;
>
>
>
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