net: fix percpu memory leaks

This patch fixes following problems :

1) percpu_counter_init() can return an error, therefore
  init_frag_mem_limit() must propagate this error so that
  inet_frags_init_net() can do the same up to its callers.

2) If ip[46]_frags_ns_ctl_register() fail, we must unwind
   properly and free the percpu_counter.

Without this fix, we leave freed object in percpu_counters
global list (if CONFIG_HOTPLUG_CPU) leading to crashes.

This bug was detected by KASAN and syzkaller tool
(http://github.com/google/syzkaller)

Fixes: 6d7b857d541e ("net: use lib/percpu_counter API for fragmentation mem accounting")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Hannes Frederic Sowa <hannes@stressinduktion.org>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 8 insertions, 3 deletions

diff --git a/net/ieee802154/6lowpan/reassembly.c b/net/ieee802154/6lowpan/reassembly.c
index 12e8cf4bda9f..6b437e8760d3 100644
--- a/net/ieee802154/6lowpan/reassembly.c
+++ b/net/ieee802154/6lowpan/reassembly.c
@@ -580,14 +580,19 @@ static int __net_init lowpan_frags_init_net(struct net *net)
 {
         struct netns_ieee802154_lowpan *ieee802154_lowpan =
                 net_ieee802154_lowpan(net);
+        int res;
 
         ieee802154_lowpan->frags.high_thresh = IPV6_FRAG_HIGH_THRESH;
         ieee802154_lowpan->frags.low_thresh = IPV6_FRAG_LOW_THRESH;
         ieee802154_lowpan->frags.timeout = IPV6_FRAG_TIMEOUT;
 
-        inet_frags_init_net(&ieee802154_lowpan->frags);
-
-        return lowpan_frags_ns_sysctl_register(net);
+        res = inet_frags_init_net(&ieee802154_lowpan->frags);
+        if (res)
+                return res;
+        res = lowpan_frags_ns_sysctl_register(net);
+        if (res)
+                inet_frags_uninit_net(&ieee802154_lowpan->frags);
+        return res;
 }
 
 static void __net_exit lowpan_frags_exit_net(struct net *net)