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authorEric Dumazet <edumazet@google.com>2015-12-03 08:53:57 +0300
committerDavid S. Miller <davem@davemloft.net>2015-12-03 19:32:06 +0300
commit6bd4f355df2eae80b8a5c7b097371cd1e05f20d5 (patch)
treee903f55cdcc87ed834790e4f257d407f886a9d23 /net/ipv6/inet6_connection_sock.c
parentc836a8ba93869d6a0290a6ae0047fbef09066871 (diff)
downloadlinux-6bd4f355df2eae80b8a5c7b097371cd1e05f20d5.tar.xz
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 <edumazet@google.com> Reported-by: Dmitry Vyukov <dvyukov@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv6/inet6_connection_sock.c')
-rw-r--r--net/ipv6/inet6_connection_sock.c10
1 files changed, 1 insertions, 9 deletions
diff --git a/net/ipv6/inet6_connection_sock.c b/net/ipv6/inet6_connection_sock.c
index 3ff5208772bb..a7ca2cde2ecb 100644
--- a/net/ipv6/inet6_connection_sock.c
+++ b/net/ipv6/inet6_connection_sock.c
@@ -111,14 +111,6 @@ void inet6_csk_addr2sockaddr(struct sock *sk, struct sockaddr *uaddr)
EXPORT_SYMBOL_GPL(inet6_csk_addr2sockaddr);
static inline
-void __inet6_csk_dst_store(struct sock *sk, struct dst_entry *dst,
- const struct in6_addr *daddr,
- const struct in6_addr *saddr)
-{
- __ip6_dst_store(sk, dst, daddr, saddr);
-}
-
-static inline
struct dst_entry *__inet6_csk_dst_check(struct sock *sk, u32 cookie)
{
return __sk_dst_check(sk, cookie);
@@ -153,7 +145,7 @@ static struct dst_entry *inet6_csk_route_socket(struct sock *sk,
dst = ip6_dst_lookup_flow(sk, fl6, final_p);
if (!IS_ERR(dst))
- __inet6_csk_dst_store(sk, dst, NULL, NULL);
+ ip6_dst_store(sk, dst, NULL, NULL);
}
return dst;
}