netdev - [PATCH net] ipv4: fix cloning issues in fib_trie

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Message-ID: <1479159274.8455.82.camel@edumazet-glaptop3.roam.corp.google.com>
Date:   Mon, 14 Nov 2016 13:34:34 -0800
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     David Miller <davem@...emloft.net>
Cc:     netdev <netdev@...r.kernel.org>,
        Alexander Duyck <alexander.h.duyck@...el.com>
Subject: [PATCH net] ipv4: fix cloning issues in fib_trie_unmerge()

From: Eric Dumazet <edumazet@...gle.com>

I had crashes in a DEBUG_PAGEALLOC kernels in fib_table_flush() or
fib_table_lookup() that I back tracked to a refcounting issue
happening when we clone struct fib_alias in fib_trie_unmerge()

While fixing this issue, I also noticed a mem leak happening
if fib_insert_alias() fails.

Fixes: 0ddcf43d5d4a0 ("ipv4: FIB Local/MAIN table collapse")
Signed-off-by: Eric Dumazet <edumazet@...gle.com>
Cc: Alexander Duyck <alexander.h.duyck@...el.com>
---
 net/ipv4/fib_trie.c |    7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/net/ipv4/fib_trie.c b/net/ipv4/fib_trie.c
index 4cff74d4133f..ebf49ab889e8 100644
--- a/net/ipv4/fib_trie.c
+++ b/net/ipv4/fib_trie.c
@@ -1737,14 +1737,19 @@ struct fib_table *fib_trie_unmerge(struct fib_table *oldtb)
 				goto out;
 
 			memcpy(new_fa, fa, sizeof(*fa));
+			if (fa->fa_info)
+				fa->fa_info->fib_treeref++;
 
 			/* insert clone into table */
 			if (!local_l)
 				local_l = fib_find_node(lt, &local_tp, l->key);
 
 			if (fib_insert_alias(lt, local_tp, local_l, new_fa,
-					     NULL, l->key))
+					     NULL, l->key)) {
+				kmem_cache_free(fn_alias_kmem, new_fa);
+				fib_release_info(fa->fa_info);
 				goto out;
+			}
 		}
 
 		/* stop loop if key wrapped back to 0 */