inetpeer: fix RCU lookup()

Excess of seafood or something happened while I cooked the commit
adding RB tree to inetpeer.

Of course, RCU rules need to be respected or bad things can happen.

In this particular loop, we need to read *pp once per iteration, not
twice.

Fixes: b145425f269a ("inetpeer: remove AVL implementation in favor of RB tree")
Reported-by: John Sperbeck <jsperbeck@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 6 insertions, 3 deletions

diff --git a/net/ipv4/inetpeer.c b/net/ipv4/inetpeer.c
index 337ad41bb80a..e7eb590c86ce 100644
--- a/net/ipv4/inetpeer.c
+++ b/net/ipv4/inetpeer.c
@@ -102,15 +102,18 @@ static struct inet_peer *lookup(const struct inetpeer_addr *daddr,
                                 struct rb_node **parent_p,
                                 struct rb_node ***pp_p)
 {
-        struct rb_node **pp, *parent;
+        struct rb_node **pp, *parent, *next;
         struct inet_peer *p;
 
         pp = &base->rb_root.rb_node;
         parent = NULL;
-        while (*pp) {
+        while (1) {
                 int cmp;
 
-                parent = rcu_dereference_raw(*pp);
+                next = rcu_dereference_raw(*pp);
+                if (!next)
+                        break;
+                parent = next;
                 p = rb_entry(parent, struct inet_peer, rb_node);
                 cmp = inetpeer_addr_cmp(daddr, &p->daddr);
                 if (cmp == 0) {