ipv4: Do not use dead fib_info entries.

Due to RCU lookups and RCU based release, fib_info objects can
be found during lookup which have fi->fib_dead set.

We must ignore these entries, otherwise we risk dereferencing
the parts of the entry which are being torn down.

Reported-by: Yevgen Pronenko <yevgen.pronenko@sonymobile.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv4/fib_trie.c b/net/ipv4/fib_trie.c
index bce36f1a37b43b5cdbc811ead5b1a01f52de82da..30b88d7b4bd61a27d396283e97633318d40d436a 100644 (file)
--- a/net/ipv4/fib_trie.c
+++ b/net/ipv4/fib_trie.c
@@ -1370,6 +1370,8 @@ static int check_leaf(struct fib_table *tb, struct trie *t, struct leaf *l,
 
                        if (fa->fa_tos && fa->fa_tos != flp->flowi4_tos)
                                continue;
+                       if (fi->fib_dead)
+                               continue;
                        if (fa->fa_info->fib_scope < flp->flowi4_scope)
                                continue;
                        fib_alias_accessed(fa);