ipv4: Do not use dead fib_info entries.

BugLink: http://bugs.launchpad.net/bugs/1013748

[ Upstream commit dccd9ecc374462e5d6a5b8f8110415a86c2213d8 ]

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Herton Ronaldo Krzesinski <herton.krzesinski@canonical.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/net/ipv4/fib_trie.c b/net/ipv4/fib_trie.c
index 58c25ea5a5c..0d884eb2b14 100644
--- a/net/ipv4/fib_trie.c
+++ b/net/ipv4/fib_trie.c
@@ -1371,6 +1371,8 @@ 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);