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Subject[PATCH net] net: ipv4: devinet: Fix crash when add/del multicast IP with autojoin
Date
From: Taras Chornyi <taras.chornyi@plvision.eu>

When CONFIG_IP_MULTICAST is not set and multicast ip is added to the device
with autojoin flag or when multicast ip is deleted kernel will crash.

steps to reptoduse:

ip addr add 224.0.0.0/32 dev eth0
ip addr del 224.0.0.0/32 dev eth0

or

ip addr add 224.0.0.0/32 dev eth0 autojoin

Unable to handle kernel NULL pointer dereference at virtual address 0000000000000088
pc : _raw_write_lock_irqsave+0x1e0/0x2ac
lr : lock_sock_nested+0x1c/0x60
Call trace:
_raw_write_lock_irqsave+0x1e0/0x2ac
lock_sock_nested+0x1c/0x60
ip_mc_config.isra.28+0x50/0xe0
inet_rtm_deladdr+0x1a8/0x1f0
rtnetlink_rcv_msg+0x120/0x350
netlink_rcv_skb+0x58/0x120
rtnetlink_rcv+0x14/0x20
netlink_unicast+0x1b8/0x270
netlink_sendmsg+0x1a0/0x3b0
____sys_sendmsg+0x248/0x290
___sys_sendmsg+0x80/0xc0
__sys_sendmsg+0x68/0xc0
__arm64_sys_sendmsg+0x20/0x30
el0_svc_common.constprop.2+0x88/0x150
do_el0_svc+0x20/0x80
el0_sync_handler+0x118/0x190
el0_sync+0x140/0x180

Fixes: 93a714d (multicast: Extend ip address command to enable multicast group join/leave on)
Signed-off-by: Taras Chornyi <taras.chornyi@plvision.eu>
Signed-off-by: Vadym Kochan <vadym.kochan@plvision.eu>
---
net/ipv4/devinet.c | 13 +++++++++----
1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/net/ipv4/devinet.c b/net/ipv4/devinet.c
index 30fa42f5997d..c0dd561aa190 100644
--- a/net/ipv4/devinet.c
+++ b/net/ipv4/devinet.c
@@ -614,12 +614,15 @@ struct in_ifaddr *inet_ifa_byprefix(struct in_device *in_dev, __be32 prefix,
return NULL;
}

-static int ip_mc_config(struct sock *sk, bool join, const struct in_ifaddr *ifa)
+static int ip_mc_autojoin_config(struct net *net, bool join,
+ const struct in_ifaddr *ifa)
{
+#if defined(CONFIG_IP_MULTICAST)
struct ip_mreqn mreq = {
.imr_multiaddr.s_addr = ifa->ifa_address,
.imr_ifindex = ifa->ifa_dev->dev->ifindex,
};
+ struct sock *sk = net->ipv4.mc_autojoin_sk;
int ret;

ASSERT_RTNL();
@@ -632,6 +635,9 @@ static int ip_mc_config(struct sock *sk, bool join, const struct in_ifaddr *ifa)
release_sock(sk);

return ret;
+#else
+ return -EOPNOTSUPP;
+#endif
}

static int inet_rtm_deladdr(struct sk_buff *skb, struct nlmsghdr *nlh,
@@ -675,7 +681,7 @@ static int inet_rtm_deladdr(struct sk_buff *skb, struct nlmsghdr *nlh,
continue;

if (ipv4_is_multicast(ifa->ifa_address))
- ip_mc_config(net->ipv4.mc_autojoin_sk, false, ifa);
+ ip_mc_autojoin_config(net, false, ifa);
__inet_del_ifa(in_dev, ifap, 1, nlh, NETLINK_CB(skb).portid);
return 0;
}
@@ -940,8 +946,7 @@ static int inet_rtm_newaddr(struct sk_buff *skb, struct nlmsghdr *nlh,
*/
set_ifa_lifetime(ifa, valid_lft, prefered_lft);
if (ifa->ifa_flags & IFA_F_MCAUTOJOIN) {
- int ret = ip_mc_config(net->ipv4.mc_autojoin_sk,
- true, ifa);
+ int ret = ip_mc_autojoin_config(net, true, ifa);

if (ret < 0) {
inet_free_ifa(ifa);
--
2.17.1
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