inetpeer: Fix data-races around sysctl.

While reading inetpeer sysctl variables, they can be changed
concurrently.  So, we need to add READ_ONCE() to avoid data-races.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv4/inetpeer.c b/net/ipv4/inetpeer.c
index da21dfc..e9fed83 100644 (file)
--- a/net/ipv4/inetpeer.c
+++ b/net/ipv4/inetpeer.c
@@ -141,16 +141,20 @@ static void inet_peer_gc(struct inet_peer_base *base,
                         struct inet_peer *gc_stack[],
                         unsigned int gc_cnt)
 {
+       int peer_threshold, peer_maxttl, peer_minttl;
        struct inet_peer *p;
        __u32 delta, ttl;
        int i;
 
-       if (base->total >= inet_peer_threshold)
+       peer_threshold = READ_ONCE(inet_peer_threshold);
+       peer_maxttl = READ_ONCE(inet_peer_maxttl);
+       peer_minttl = READ_ONCE(inet_peer_minttl);
+
+       if (base->total >= peer_threshold)
                ttl = 0; /* be aggressive */
        else
-               ttl = inet_peer_maxttl
-                               - (inet_peer_maxttl - inet_peer_minttl) / HZ *
-                                       base->total / inet_peer_threshold * HZ;
+               ttl = peer_maxttl - (peer_maxttl - peer_minttl) / HZ *
+                       base->total / peer_threshold * HZ;
        for (i = 0; i < gc_cnt; i++) {
                p = gc_stack[i];