Re: [PATCH v1] ipv4: add iPv4_is_multicast() check in ip_mc_leave_group().
From: Jakub Kicinski <kuba@kernel.org>
Date: 2021-01-19 04:46:03
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On Sun, 17 Jan 2021 05:34:16 -0800 wangyingjie55@126.com wrote:
From: Yingjie Wang <redacted> 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.
quoted hunk ↗ jump to hunk
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 <redacted> --- 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);