path: root/net/dccp
diff options
authorEric Dumazet <>2015-12-02 21:53:57 -0800
committerDavid S. Miller <>2015-12-03 11:32:06 -0500
commit6bd4f355df2eae80b8a5c7b097371cd1e05f20d5 (patch)
treee903f55cdcc87ed834790e4f257d407f886a9d23 /net/dccp
parentc836a8ba93869d6a0290a6ae0047fbef09066871 (diff)
ipv6: kill sk_dst_lock
While testing the np->opt RCU conversion, I found that UDP/IPv6 was using a mixture of xchg() and sk_dst_lock to protect concurrent changes to sk->sk_dst_cache, leading to possible corruptions and crashes. ip6_sk_dst_lookup_flow() uses sk_dst_check() anyway, so the simplest way to fix the mess is to remove sk_dst_lock completely, as we did for IPv4. __ip6_dst_store() and ip6_dst_store() share same implementation. sk_setup_caps() being called with socket lock being held or not, we have to use sk_dst_set() instead of __sk_dst_set() Note that I had to move the "np->dst_cookie = rt6_get_cookie(rt);" in ip6_dst_store() before the sk_setup_caps(sk, dst) call. This is because ip6_dst_store() can be called from process context, without any lock held. As soon as the dst is installed in sk->sk_dst_cache, dst can be freed from another cpu doing a concurrent ip6_dst_store() Doing the dst dereference before doing the install is needed to make sure no use after free would trigger. Signed-off-by: Eric Dumazet <> Reported-by: Dmitry Vyukov <> Signed-off-by: David S. Miller <>
Diffstat (limited to 'net/dccp')
1 files changed, 2 insertions, 2 deletions
diff --git a/net/dccp/ipv6.c b/net/dccp/ipv6.c
index e7e0b9bc2a43..9c6d0508e63a 100644
--- a/net/dccp/ipv6.c
+++ b/net/dccp/ipv6.c
@@ -459,7 +459,7 @@ static struct sock *dccp_v6_request_recv_sock(const struct sock *sk,
* comment in that function for the gory details. -acme
- __ip6_dst_store(newsk, dst, NULL, NULL);
+ ip6_dst_store(newsk, dst, NULL, NULL);
newsk->sk_route_caps = dst->dev->features & ~(NETIF_F_IP_CSUM |
newdp6 = (struct dccp6_sock *)newsk;
@@ -883,7 +883,7 @@ static int dccp_v6_connect(struct sock *sk, struct sockaddr *uaddr,
np->saddr = *saddr;
inet->inet_rcv_saddr = LOOPBACK4_IPV6;
- __ip6_dst_store(sk, dst, NULL, NULL);
+ ip6_dst_store(sk, dst, NULL, NULL);
icsk->icsk_ext_hdr_len = 0;
if (opt)