batman-adv: Fix netlink dumping of BLA backbones

[ Upstream commit fce672db548ff19e76a08a32a829544617229bc2 ]

The function batadv_bla_backbone_dump_bucket must be able to handle
non-complete dumps of a single bucket. It tries to do that by saving the
latest dumped index in *idx_skip to inform the caller about the current
state.

But the caller only assumes that buckets were not completely dumped when
the return code is non-zero. This function must therefore also return a
non-zero index when the dumping of an entry failed. Otherwise the caller
will just skip all remaining buckets.

And the function must also reset *idx_skip back to zero when it finished a
bucket. Otherwise it will skip the same number of entries in the next
bucket as the previous one had.

Fixes: ea4152e11716 ("batman-adv: add backbone table netlink support")
Reported-by: Linus Lüssing <linus.luessing@c0d3.blue>
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/net/batman-adv/bridge_loop_avoidance.c b/net/batman-adv/bridge_loop_avoidance.c
index 7832a3676bd157ad1321413aeff3c3acf1f9ca76..582e27698bf09ff44ca95f5e52583f17671e4532 100644 (file)
--- a/net/batman-adv/bridge_loop_avoidance.c
+++ b/net/batman-adv/bridge_loop_avoidance.c
@@ -2382,22 +2382,25 @@ batadv_bla_backbone_dump_bucket(struct sk_buff *msg, u32 portid, u32 seq,
 {
        struct batadv_bla_backbone_gw *backbone_gw;
        int idx = 0;
+       int ret = 0;
 
        rcu_read_lock();
        hlist_for_each_entry_rcu(backbone_gw, head, hash_entry) {
                if (idx++ < *idx_skip)
                        continue;
-               if (batadv_bla_backbone_dump_entry(msg, portid, seq,
-                                                  primary_if, backbone_gw)) {
+
+               ret = batadv_bla_backbone_dump_entry(msg, portid, seq,
+                                                    primary_if, backbone_gw);
+               if (ret) {
                        *idx_skip = idx - 1;
                        goto unlock;
                }
        }
 
-       *idx_skip = idx;
+       *idx_skip = 0;
 unlock:
        rcu_read_unlock();
-       return 0;
+       return ret;
 }
 
 /**