Stefano Garzarella <sgarz...@redhat.com> writes:
> net_client_init() uses a variable length array to store the prefix
> of 'ipv6-net' parameter (e.g. if ipv6-net=fec0::0/64, the prefix
> is 'fec0::0').
> Since the IPv6 prefix can be at most as long as an IPv6 address,
> we can use an array with fixed size equals to INET6_ADDRSTRLEN.
>
> Signed-off-by: Stefano Garzarella <sgarz...@redhat.com>
> ---
> net/net.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/net/net.c b/net/net.c
> index f3a3c5444c..2e5f27e121 100644
> --- a/net/net.c
> +++ b/net/net.c
> @@ -1118,7 +1118,7 @@ static int net_client_init(QemuOpts *opts, bool
> is_netdev, Error **errp)
> const char *ip6_net = qemu_opt_get(opts, "ipv6-net");
>
> if (ip6_net) {
> - char buf[strlen(ip6_net) + 1];
> + char buf[INET6_ADDRSTRLEN];
>
> if (get_str_sep(buf, sizeof(buf), &ip6_net, '/') < 0) {
> /* Default 64bit prefix length. */
Hmm.
Parameter "ipv6-net" is of the form ADDRESS[/PREFIX-SIZE]. If
/PREFIX-SIZE is present, get_str_sep() copies the ADDRESS part to buf[].
However, nothing stops the user from passing in an ADDRESS longer than
INET6_ADDRSTRLEN, say by adding a enough leading zeros. get_str_sep()
will then silently truncate ADDRESS.
Suggest to avoid get_str_sep() like this (not even compile-tested):
if (ip6_net) {
char *slashp = strchr(ip6_net, '/');
if (!slashp) {
/* Default 64bit prefix length. */
qemu_opt_set(opts, "ipv6-prefix", ip6_net, &error_abort);
qemu_opt_set_number(opts, "ipv6-prefixlen", 64, &error_abort);
} else {
/* User-specified prefix length. */
unsigned long len;
int err;
char *addr = g_strndup(ip6_net, slashp - ip6_net);
qemu_opt_set(opts, "ipv6-prefix", addr, &error_abort);
g_free(addr);
err = qemu_strtoul(slashp + 1, NULL, 10, &len);
if (err) {
error_setg(errp, QERR_INVALID_PARAMETER_VALUE,
"ipv6-prefix", "a number");
} else {
qemu_opt_set_number(opts, "ipv6-prefixlen", len,
&error_abort);
}
}
qemu_opt_unset(opts, "ipv6-net");
}
}
I'd be tempted to clean up further; de-duplicate the qemu_opt_set() and
qemu_opt_set_number().
There's just one more use of get_str_sep(), in parse_host_port(), and it
looks just as prone to silent truncation.
