6.6-stable review patch. If anyone has any objections, please let me know.
------------------
From: Eric Dumazet <edumazet@xxxxxxxxxx>
[ Upstream commit 087c1faa594fa07a66933d750c0b2610aa1a2946 ]
igmp6_send() can be called without RTNL or RCU being held.
Extend RCU protection so that we can safely fetch the net pointer
and avoid a potential UAF.
Note that we no longer can use sock_alloc_send_skb() because
ipv6.igmp_sk uses GFP_KERNEL allocations which can sleep.
Instead use alloc_skb() and charge the net->ipv6.igmp_sk
socket under RCU protection.
Fixes: b8ad0cbc58f7 ("[NETNS][IPV6] mcast - handle several network namespace")
Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Reviewed-by: David Ahern <dsahern@xxxxxxxxxx>
Reviewed-by: Kuniyuki Iwashima <kuniyu@xxxxxxxxxx>
Link: https://patch.msgid.link/20250207135841.1948589-9-edumazet@xxxxxxxxxx
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
net/ipv6/mcast.c | 31 +++++++++++++++----------------
1 file changed, 15 insertions(+), 16 deletions(-)
diff --git a/net/ipv6/mcast.c b/net/ipv6/mcast.c
index 6e2f77a95a657..a502669b2b28a 100644
--- a/net/ipv6/mcast.c
+++ b/net/ipv6/mcast.c
@@ -2121,21 +2121,21 @@ static void mld_send_cr(struct inet6_dev *idev)
static void igmp6_send(struct in6_addr *addr, struct net_device *dev, int type)
{
- struct net *net = dev_net(dev);
- struct sock *sk = net->ipv6.igmp_sk;
+ const struct in6_addr *snd_addr, *saddr;
+ int err, len, payload_len, full_len;
+ struct in6_addr addr_buf;
struct inet6_dev *idev;
struct sk_buff *skb;
struct mld_msg *hdr;
- const struct in6_addr *snd_addr, *saddr;
- struct in6_addr addr_buf;
int hlen = LL_RESERVED_SPACE(dev);
int tlen = dev->needed_tailroom;
- int err, len, payload_len, full_len;
u8 ra[8] = { IPPROTO_ICMPV6, 0,
IPV6_TLV_ROUTERALERT, 2, 0, 0,
IPV6_TLV_PADN, 0 };
- struct flowi6 fl6;
struct dst_entry *dst;
+ struct flowi6 fl6;
+ struct net *net;
+ struct sock *sk;
if (type == ICMPV6_MGM_REDUCTION)
snd_addr = &in6addr_linklocal_allrouters;
@@ -2146,19 +2146,21 @@ static void igmp6_send(struct in6_addr *addr, struct net_device *dev, int type)
payload_len = len + sizeof(ra);
full_len = sizeof(struct ipv6hdr) + payload_len;
- rcu_read_lock();
- IP6_INC_STATS(net, __in6_dev_get(dev), IPSTATS_MIB_OUTREQUESTS);
- rcu_read_unlock();
+ skb = alloc_skb(hlen + tlen + full_len, GFP_KERNEL);
- skb = sock_alloc_send_skb(sk, hlen + tlen + full_len, 1, &err);
+ rcu_read_lock();
+ net = dev_net_rcu(dev);
+ idev = __in6_dev_get(dev);
+ IP6_INC_STATS(net, idev, IPSTATS_MIB_OUTREQUESTS);
if (!skb) {
- rcu_read_lock();
- IP6_INC_STATS(net, __in6_dev_get(dev),
- IPSTATS_MIB_OUTDISCARDS);
+ IP6_INC_STATS(net, idev, IPSTATS_MIB_OUTDISCARDS);
rcu_read_unlock();
return;
}
+ sk = net->ipv6.igmp_sk;
+ skb_set_owner_w(skb, sk);
+
skb->priority = TC_PRIO_CONTROL;
skb_reserve(skb, hlen);
@@ -2183,9 +2185,6 @@ static void igmp6_send(struct in6_addr *addr, struct net_device *dev, int type)
IPPROTO_ICMPV6,
csum_partial(hdr, len, 0));
- rcu_read_lock();
- idev = __in6_dev_get(skb->dev);
-
icmpv6_flow_init(sk, &fl6, type,
&ipv6_hdr(skb)->saddr, &ipv6_hdr(skb)->daddr,
skb->dev->ifindex);
--
2.39.5
