On Sun, 17 Jan 2021 05:34:16 -0800 wangyingji...@126.com wrote:
> From: Yingjie Wang <wangyingji...@126.com>
>
> There is no iPv4_is_multicast() check added to ip_mc_leave_group()
> to check if imr->imr_multiaddr.s_addr is a multicast address.
> If not a multicast address, it may result in an error.
Could you please say more? From looking at the code it seems like
no address should match if group is non-mcast, and -EADDRNOTAVAIL
will be returned.
Adding Nik to CC.
> In some cases, the callers of ip_mc_leave_group() don't check
> whether it is multicast address or not before calling
> such as do_ip_setsockopt(). So I suggest adding the ipv4_is_multicast()
> check to the ip_mc_leave_group() to prevent this from happening.
>
> Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
> Signed-off-by: Yingjie Wang <wangyingji...@126.com>
> ---
> net/ipv4/igmp.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/net/ipv4/igmp.c b/net/ipv4/igmp.c
> index 7b272bbed2b4..1b6f91271cfd 100644
> --- a/net/ipv4/igmp.c
> +++ b/net/ipv4/igmp.c
> @@ -2248,6 +2248,9 @@ int ip_mc_leave_group(struct sock *sk, struct ip_mreqn
> *imr)
> u32 ifindex;
> int ret = -EADDRNOTAVAIL;
>
> + if (!ipv4_is_multicast(group))
> + return -EINVAL;
> +
> ASSERT_RTNL();
>
> in_dev = ip_mc_find_dev(net, imr);
