Re: [Qemu-devel] [PATCH for-4.0] target/i386: Generate #UD for LOCK on a register increment

[Paolo Bonzini]

On 28/03/19 11:47, Peter Maydell wrote:
> Fix a TCG crash due to attempting an atomic increment
> operation without having set up the address first.
> This is a similar case to that dealt with in commit
> e84fcd7f662a0d8198703, and we fix it in the same way.
> 
> Fixes: https://bugs.launchpad.net/qemu/+bug/1807675
> Signed-off-by: Peter Maydell <address@hidden>
> ---
>  target/i386/translate.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/target/i386/translate.c b/target/i386/translate.c
> index 49cd298374b..b725bec37cd 100644
> --- a/target/i386/translate.c
> +++ b/target/i386/translate.c
> @@ -1398,6 +1398,11 @@ static void gen_op(DisasContext *s1, int op, TCGMemOp 
> ot, int d)
>  static void gen_inc(DisasContext *s1, TCGMemOp ot, int d, int c)
>  {
>      if (s1->prefix & PREFIX_LOCK) {
> +        if (d != OR_TMP0) {
> +            /* Lock prefix when destination is not memory */
> +            gen_illegal_opcode(s1);
> +            return;
> +        }
>          tcg_gen_movi_tl(s1->T0, c > 0 ? 1 : -1);
>          tcg_gen_atomic_add_fetch_tl(s1->T0, s1->A0, s1->T0,
>                                      s1->mem_index, ot | MO_LE);
> 

Acked-by: Paolo Bonzini <address@hidden>

Feel free to apply it yourself.

Paolo