inet: annotate data-races around ifa->ifa_tstamp and ifa->ifa_cstamp

ifa->ifa_tstamp can be read locklessly.

Add appropriate READ_ONCE()/WRITE_ONCE() annotations.

Do the same for ifa->ifa_cstamp to prepare upcoming changes.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv4/devinet.c b/net/ipv4/devinet.c
index af741af61830aeb695e7e75608515547dade8f39..1316046d5f28955376091d9e02ab4594e19fbd09 100644 (file)
--- a/net/ipv4/devinet.c
+++ b/net/ipv4/devinet.c
@@ -713,13 +713,14 @@ static void check_lifetime(struct work_struct *work)
 
                rcu_read_lock();
                hlist_for_each_entry_rcu(ifa, &inet_addr_lst[i], hash) {
-                       unsigned long age;
+                       unsigned long age, tstamp;
 
                        if (ifa->ifa_flags & IFA_F_PERMANENT)
                                continue;
 
+                       tstamp = READ_ONCE(ifa->ifa_tstamp);
                        /* We try to batch several events at once. */
-                       age = (now - ifa->ifa_tstamp +
+                       age = (now - tstamp +
                               ADDRCONF_TIMER_FUZZ_MINUS) / HZ;
 
                        if (ifa->ifa_valid_lft != INFINITY_LIFE_TIME &&
@@ -729,17 +730,17 @@ static void check_lifetime(struct work_struct *work)
                                   INFINITY_LIFE_TIME) {
                                continue;
                        } else if (age >= ifa->ifa_preferred_lft) {
-                               if (time_before(ifa->ifa_tstamp +
+                               if (time_before(tstamp +
                                                ifa->ifa_valid_lft * HZ, next))
-                                       next = ifa->ifa_tstamp +
+                                       next = tstamp +
                                               ifa->ifa_valid_lft * HZ;
 
                                if (!(ifa->ifa_flags & IFA_F_DEPRECATED))
                                        change_needed = true;
-                       } else if (time_before(ifa->ifa_tstamp +
+                       } else if (time_before(tstamp +
                                               ifa->ifa_preferred_lft * HZ,
                                               next)) {
-                               next = ifa->ifa_tstamp +
+                               next = tstamp +
                                       ifa->ifa_preferred_lft * HZ;
                        }
                }
@@ -819,9 +820,9 @@ static void set_ifa_lifetime(struct in_ifaddr *ifa, __u32 valid_lft,
                        ifa->ifa_flags |= IFA_F_DEPRECATED;
                ifa->ifa_preferred_lft = timeout;
        }
-       ifa->ifa_tstamp = jiffies;
+       WRITE_ONCE(ifa->ifa_tstamp, jiffies);
        if (!ifa->ifa_cstamp)
-               ifa->ifa_cstamp = ifa->ifa_tstamp;
+               WRITE_ONCE(ifa->ifa_cstamp, ifa->ifa_tstamp);
 }
 
 static struct in_ifaddr *rtm_to_ifaddr(struct net *net, struct nlmsghdr *nlh,
@@ -1676,6 +1677,7 @@ static int inet_fill_ifaddr(struct sk_buff *skb, struct in_ifaddr *ifa,
 {
        struct ifaddrmsg *ifm;
        struct nlmsghdr  *nlh;
+       unsigned long tstamp;
        u32 preferred, valid;
 
        nlh = nlmsg_put(skb, args->portid, args->seq, args->event, sizeof(*ifm),
@@ -1694,11 +1696,12 @@ static int inet_fill_ifaddr(struct sk_buff *skb, struct in_ifaddr *ifa,
            nla_put_s32(skb, IFA_TARGET_NETNSID, args->netnsid))
                goto nla_put_failure;
 
+       tstamp = READ_ONCE(ifa->ifa_tstamp);
        if (!(ifm->ifa_flags & IFA_F_PERMANENT)) {
                preferred = ifa->ifa_preferred_lft;
                valid = ifa->ifa_valid_lft;
                if (preferred != INFINITY_LIFE_TIME) {
-                       long tval = (jiffies - ifa->ifa_tstamp) / HZ;
+                       long tval = (jiffies - tstamp) / HZ;
 
                        if (preferred > tval)
                                preferred -= tval;
@@ -1728,7 +1731,7 @@ static int inet_fill_ifaddr(struct sk_buff *skb, struct in_ifaddr *ifa,
            nla_put_u32(skb, IFA_FLAGS, ifa->ifa_flags) ||
            (ifa->ifa_rt_priority &&
             nla_put_u32(skb, IFA_RT_PRIORITY, ifa->ifa_rt_priority)) ||
-           put_cacheinfo(skb, ifa->ifa_cstamp, ifa->ifa_tstamp,
+           put_cacheinfo(skb, READ_ONCE(ifa->ifa_cstamp), tstamp,
                          preferred, valid))
                goto nla_put_failure;