Re: [PATCH 1/3] target/ppc/kvm: Replace variable length array in kvmppc_save_htab()

[Peter Maydell]

On Wed, 21 Feb 2024 at 16:26, Thomas Huth <thuth@redhat.com> wrote:
>
> To be able to compile QEMU with -Wvla (to prevent potential security
> issues), we need to get rid of the variable length array in the
> kvmppc_save_htab() function. Replace it with a heap allocation instead.
>
> Signed-off-by: Thomas Huth <thuth@redhat.com>
> ---
>  target/ppc/kvm.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/target/ppc/kvm.c b/target/ppc/kvm.c
> index 26fa9d0575..e7e39c3091 100644
> --- a/target/ppc/kvm.c
> +++ b/target/ppc/kvm.c
> @@ -2688,7 +2688,7 @@ int kvmppc_get_htab_fd(bool write, uint64_t index, 
> Error **errp)
>  int kvmppc_save_htab(QEMUFile *f, int fd, size_t bufsize, int64_t max_ns)
>  {
>      int64_t starttime = qemu_clock_get_ns(QEMU_CLOCK_REALTIME);
> -    uint8_t buf[bufsize];
> +    g_autofree uint8_t *buf = g_malloc(bufsize);
>      ssize_t rc;
>

This works, so
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>

but you could also drop the bufsize argument, because there are only
two callers and they both pass MAX_KVM_BUF_SIZE, and then declare the
array as fixed size with "uint8_t buf[MAX_KVM_BUF_SIZE]".

thanks
-- PMM