fib_trie: Avoid NULL pointer if local table is not allocated
The function fib_unmerge assumed the local table had already been
allocated. If that is not the case however when custom rules are applied
then this can result in a NULL pointer dereference.
In order to prevent this we must check the value of the local table pointer
and if it is NULL simply return 0 as there is no local table to separate
from the main.
Fixes: 0ddcf43d5 ("ipv4: FIB Local/MAIN table collapse")
Reported-by: Madhu Challa <challa@noironetworks.com>
Signed-off-by: Alexander Duyck <alexander.h.duyck@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/fib_frontend.c b/net/ipv4/fib_frontend.c
index c1caf9d..e5b6b05 100644
--- a/net/ipv4/fib_frontend.c
+++ b/net/ipv4/fib_frontend.c
@@ -156,9 +156,12 @@
{
struct fib_table *old, *new;
+ /* attempt to fetch local table if it has been allocated */
old = fib_get_table(net, RT_TABLE_LOCAL);
- new = fib_trie_unmerge(old);
+ if (!old)
+ return 0;
+ new = fib_trie_unmerge(old);
if (!new)
return -ENOMEM;