Re: [PATCH v4 37/45] linux-user/aarch64: Do not allow duplicate or short sve records

[Peter Maydell]

On Tue, 28 Jun 2022 at 05:50, Richard Henderson
<richard.henderson@linaro.org> wrote:
>
> In parse_user_sigframe, the kernel rejects duplicate sve records,
> or records that are smaller than the header.  We were silently
> allowing these cases to pass, dropping the record.
>
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> ---
>  linux-user/aarch64/signal.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/linux-user/aarch64/signal.c b/linux-user/aarch64/signal.c
> index 8b352abb97..8fbe98d72f 100644
> --- a/linux-user/aarch64/signal.c
> +++ b/linux-user/aarch64/signal.c
> @@ -318,10 +318,13 @@ static int target_restore_sigframe(CPUARMState *env,
>              break;
>
>          case TARGET_SVE_MAGIC:
> +            if (sve || size < sizeof(struct target_sve_context)) {
> +                goto err;
> +            }
>              if (cpu_isar_feature(aa64_sve, env_archcpu(env))) {
>                  vq = sve_vq(env);
>                  sve_size = QEMU_ALIGN_UP(TARGET_SVE_SIG_CONTEXT_SIZE(vq), 
> 16);
> -                if (!sve && size == sve_size) {
> +                if (size == sve_size) {
>                      sve = (struct target_sve_context *)ctx;
>                      break;
>                  }

On the other hand, the kernel seems to happily allow records
which are larger than the SVE_SIG_CONTEXT_SIZE, whereas we
ignore the record unless there's an exact size match.

I notice the kernel has a bunch of signal frame test
cases in  tools/testing/selftests/arm64/signal/testcases --
do we pass those ?

thanks
-- PMM