[ 30/47] ipv4: Do not use dead fib_info entries.

[Greg KH]

3.0-stable review patch.  If anyone has any objections, please let me know.

------------------


From: "David S. Miller" <davem@xxxxxxxxxxxxx>

[ 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@xxxxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 net/ipv4/fib_trie.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/net/ipv4/fib_trie.c
+++ b/net/ipv4/fib_trie.c
@@ -1371,6 +1371,8 @@ static int check_leaf(struct fib_table *
 
 			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);


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