[UDP6]: Fix flowi clobbering

The udp6_sendmsg function uses a shared buffer to store the
flow without taking any locks.  This leads to races with SMP.
This patch moves the flowi object onto the stack.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Acked-by: James Morris <jmorris@namei.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index 9662561701d1c8463b53f0f1fe73dd89a2ba44d7..552ec0f449af1e1c5e8fdd6cf70ee07827dd874c 100644 (file)
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -546,7 +546,7 @@ static int udpv6_sendmsg(struct kiocb *iocb, struct sock *sk,
        struct in6_addr *daddr, *final_p = NULL, final;
        struct ipv6_txoptions *opt = NULL;
        struct ip6_flowlabel *flowlabel = NULL;
-       struct flowi *fl = &inet->cork.fl;
+       struct flowi fl;
        struct dst_entry *dst;
        int addr_len = msg->msg_namelen;
        int ulen = len;
@@ -626,19 +626,19 @@ do_udp_sendmsg:
        }
        ulen += sizeof(struct udphdr);
 
-       memset(fl, 0, sizeof(*fl));
+       memset(&fl, 0, sizeof(fl));
 
        if (sin6) {
                if (sin6->sin6_port == 0)
                        return -EINVAL;
 
-               fl->fl_ip_dport = sin6->sin6_port;
+               fl.fl_ip_dport = sin6->sin6_port;
                daddr = &sin6->sin6_addr;
 
                if (np->sndflow) {
-                       fl->fl6_flowlabel = sin6->sin6_flowinfo&IPV6_FLOWINFO_MASK;
-                       if (fl->fl6_flowlabel&IPV6_FLOWLABEL_MASK) {
-                               flowlabel = fl6_sock_lookup(sk, fl->fl6_flowlabel);
+                       fl.fl6_flowlabel = sin6->sin6_flowinfo&IPV6_FLOWINFO_MASK;
+                       if (fl.fl6_flowlabel&IPV6_FLOWLABEL_MASK) {
+                               flowlabel = fl6_sock_lookup(sk, fl.fl6_flowlabel);
                                if (flowlabel == NULL)
                                        return -EINVAL;
                                daddr = &flowlabel->dst;
@@ -656,32 +656,32 @@ do_udp_sendmsg:
                if (addr_len >= sizeof(struct sockaddr_in6) &&
                    sin6->sin6_scope_id &&
                    ipv6_addr_type(daddr)&IPV6_ADDR_LINKLOCAL)
-                       fl->oif = sin6->sin6_scope_id;
+                       fl.oif = sin6->sin6_scope_id;
        } else {
                if (sk->sk_state != TCP_ESTABLISHED)
                        return -EDESTADDRREQ;
 
-               fl->fl_ip_dport = inet->dport;
+               fl.fl_ip_dport = inet->dport;
                daddr = &np->daddr;
-               fl->fl6_flowlabel = np->flow_label;
+               fl.fl6_flowlabel = np->flow_label;
                connected = 1;
        }
 
-       if (!fl->oif)
-               fl->oif = sk->sk_bound_dev_if;
+       if (!fl.oif)
+               fl.oif = sk->sk_bound_dev_if;
 
        if (msg->msg_controllen) {
                opt = &opt_space;
                memset(opt, 0, sizeof(struct ipv6_txoptions));
                opt->tot_len = sizeof(*opt);
 
-               err = datagram_send_ctl(msg, fl, opt, &hlimit, &tclass);
+               err = datagram_send_ctl(msg, &fl, opt, &hlimit, &tclass);
                if (err < 0) {
                        fl6_sock_release(flowlabel);
                        return err;
                }
-               if ((fl->fl6_flowlabel&IPV6_FLOWLABEL_MASK) && !flowlabel) {
-                       flowlabel = fl6_sock_lookup(sk, fl->fl6_flowlabel);
+               if ((fl.fl6_flowlabel&IPV6_FLOWLABEL_MASK) && !flowlabel) {
+                       flowlabel = fl6_sock_lookup(sk, fl.fl6_flowlabel);
                        if (flowlabel == NULL)
                                return -EINVAL;
                }
@@ -695,39 +695,39 @@ do_udp_sendmsg:
                opt = fl6_merge_options(&opt_space, flowlabel, opt);
        opt = ipv6_fixup_options(&opt_space, opt);
 
-       fl->proto = IPPROTO_UDP;
-       ipv6_addr_copy(&fl->fl6_dst, daddr);
-       if (ipv6_addr_any(&fl->fl6_src) && !ipv6_addr_any(&np->saddr))
-               ipv6_addr_copy(&fl->fl6_src, &np->saddr);
-       fl->fl_ip_sport = inet->sport;
+       fl.proto = IPPROTO_UDP;
+       ipv6_addr_copy(&fl.fl6_dst, daddr);
+       if (ipv6_addr_any(&fl.fl6_src) && !ipv6_addr_any(&np->saddr))
+               ipv6_addr_copy(&fl.fl6_src, &np->saddr);
+       fl.fl_ip_sport = inet->sport;
        
        /* merge ip6_build_xmit from ip6_output */
        if (opt && opt->srcrt) {
                struct rt0_hdr *rt0 = (struct rt0_hdr *) opt->srcrt;
-               ipv6_addr_copy(&final, &fl->fl6_dst);
-               ipv6_addr_copy(&fl->fl6_dst, rt0->addr);
+               ipv6_addr_copy(&final, &fl.fl6_dst);
+               ipv6_addr_copy(&fl.fl6_dst, rt0->addr);
                final_p = &final;
                connected = 0;
        }
 
-       if (!fl->oif && ipv6_addr_is_multicast(&fl->fl6_dst)) {
-               fl->oif = np->mcast_oif;
+       if (!fl.oif && ipv6_addr_is_multicast(&fl.fl6_dst)) {
+               fl.oif = np->mcast_oif;
                connected = 0;
        }
 
-       security_sk_classify_flow(sk, fl);
+       security_sk_classify_flow(sk, &fl);
 
-       err = ip6_sk_dst_lookup(sk, &dst, fl);
+       err = ip6_sk_dst_lookup(sk, &dst, &fl);
        if (err)
                goto out;
        if (final_p)
-               ipv6_addr_copy(&fl->fl6_dst, final_p);
+               ipv6_addr_copy(&fl.fl6_dst, final_p);
 
-       if ((err = xfrm_lookup(&dst, fl, sk, 0)) < 0)
+       if ((err = xfrm_lookup(&dst, &fl, sk, 0)) < 0)
                goto out;
 
        if (hlimit < 0) {
-               if (ipv6_addr_is_multicast(&fl->fl6_dst))
+               if (ipv6_addr_is_multicast(&fl.fl6_dst))
                        hlimit = np->mcast_hops;
                else
                        hlimit = np->hop_limit;
@@ -763,7 +763,7 @@ back_from_confirm:
 do_append_data:
        up->len += ulen;
        err = ip6_append_data(sk, ip_generic_getfrag, msg->msg_iov, ulen,
-               sizeof(struct udphdr), hlimit, tclass, opt, fl,
+               sizeof(struct udphdr), hlimit, tclass, opt, &fl,
                (struct rt6_info*)dst,
                corkreq ? msg->msg_flags|MSG_MORE : msg->msg_flags);
        if (err)
@@ -774,10 +774,10 @@ do_append_data:
        if (dst) {
                if (connected) {
                        ip6_dst_store(sk, dst,
-                                     ipv6_addr_equal(&fl->fl6_dst, &np->daddr) ?
+                                     ipv6_addr_equal(&fl.fl6_dst, &np->daddr) ?
                                      &np->daddr : NULL,
 #ifdef CONFIG_IPV6_SUBTREES
-                                     ipv6_addr_equal(&fl->fl6_src, &np->saddr) ?
+                                     ipv6_addr_equal(&fl.fl6_src, &np->saddr) ?
                                      &np->saddr :
 #endif
                                      NULL);