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fib_trie: remove potential out of bound access 

AddressSanitizer [1] dynamic checker pointed a potential
out of bound access in leaf_walk_rcu()

We could allocate one more slot in tnode_new() to leave the prefetch()
in-place but it looks not worth the pain.

Bug added in commit 82cfbb0085 ("[IPV4] fib_trie: iterator recode")

[1] :
https://code.google.com/p/address-sanitizer/wiki/AddressSanitizerForKernel

Reported-by: Andrey Konovalov <andreyknvl@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2013-08-05 11:18:49 -07:00 committed by David S. Miller
parent 3b380877d5
commit aab515d7c3
1 changed files with 1 additions and 4 deletions
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5
net/ipv4/fib_trie.c
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@ -71,7 +71,6 @@
#include <linux/init.h>
#include <linux/list.h>
#include <linux/slab.h>
#include <linux/prefetch.h>
#include <linux/export.h>
#include <net/net_namespace.h>
#include <net/ip.h>
@ -1761,10 +1760,8 @@ static struct leaf *leaf_walk_rcu(struct tnode *p, struct rt_trie_node *c)
if (!c)
continue;
if (IS_LEAF(c)) {
prefetch(rcu_dereference_rtnl(p->child[idx]));
if (IS_LEAF(c))
return (struct leaf *) c;
}
/* Rescan start scanning in new node */
p = (struct tnode *) c;