[PATCH 4.19 25/35] net: batman-adv: fix error handling

Greg Kroah-Hartman
2021-11-01T09:26:01Z

From: Pavel Skripkin <paskripkin@gmail.com>

commit 6f68cd634856f8ca93bafd623ba5357e0f648c68 upstream.

Syzbot reported ODEBUG warning in batadv_nc_mesh_free(). The problem was
in wrong error handling in batadv_mesh_init().

Before this patch batadv_mesh_init() was calling batadv_mesh_free() in case
of any batadv_*_init() calls failure. This approach may work well, when
there is some kind of indicator, which can tell which parts of batadv are
initialized; but there isn't any.

All written above lead to cleaning up uninitialized fields. Even if we hide
ODEBUG warning by initializing bat_priv->nc.work, syzbot was able to hit
GPF in batadv_nc_purge_paths(), because hash pointer in still NULL. [1]

To fix these bugs we can unwind batadv_*_init() calls one by one.
It is good approach for 2 reasons: 1) It fixes bugs on error handling
path 2) It improves the performance, since we won't call unneeded
batadv_*_free() functions.

So, this patch makes all batadv_*_init() clean up all allocated memory
before returning with an error to no call correspoing batadv_*_free()
and open-codes batadv_mesh_free() with proper order to avoid touching
uninitialized fields.

Link: https://lore.kernel.org/netdev/000000000000c87fbd05cef6bcb0@google.com/ [1]
Reported-and-tested-by: syzbot+28b0702ada0bf7381f58@syzkaller.appspotmail.com
Fixes: c6c8fea29769 ("net: Add batman-adv meshing protocol")
Signed-off-by: Pavel Skripkin <paskripkin@gmail.com>
Acked-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/batman-adv/bridge_loop_avoidance.c | 8 +++-
net/batman-adv/main.c | 56 +++++++++++++++++++++++----------
net/batman-adv/network-coding.c | 4 +-
net/batman-adv/translation-table.c | 4 +-
4 files changed, 52 insertions(+), 20 deletions(-)

--- a/net/batman-adv/bridge_loop_avoidance.c
+++ b/net/batman-adv/bridge_loop_avoidance.c
@@ -1574,10 +1574,14 @@ int batadv_bla_init(struct batadv_priv *
return 0;

bat_priv->bla.claim_hash = batadv_hash_new(128);
- bat_priv->bla.backbone_hash = batadv_hash_new(32);
+ if (!bat_priv->bla.claim_hash)
+ return -ENOMEM;

- if (!bat_priv->bla.claim_hash || !bat_priv->bla.backbone_hash)
+ bat_priv->bla.backbone_hash = batadv_hash_new(32);
+ if (!bat_priv->bla.backbone_hash) {
+ batadv_hash_destroy(bat_priv->bla.claim_hash);
return -ENOMEM;
+ }

batadv_hash_set_lock_class(bat_priv->bla.claim_hash,
&batadv_claim_hash_lock_class_key);
--- a/net/batman-adv/main.c
+++ b/net/batman-adv/main.c
@@ -187,29 +187,41 @@ int batadv_mesh_init(struct net_device *
INIT_HLIST_HEAD(&bat_priv->softif_vlan_list);
INIT_HLIST_HEAD(&bat_priv->tp_list);

- ret = batadv_v_mesh_init(bat_priv);
- if (ret < 0)
- goto err;
-
ret = batadv_originator_init(bat_priv);
- if (ret < 0)
- goto err;
+ if (ret < 0) {
+ atomic_set(&bat_priv->mesh_state, BATADV_MESH_DEACTIVATING);
+ goto err_orig;
+ }

ret = batadv_tt_init(bat_priv);
- if (ret < 0)
- goto err;
+ if (ret < 0) {
+ atomic_set(&bat_priv->mesh_state, BATADV_MESH_DEACTIVATING);
+ goto err_tt;
+ }
+
+ ret = batadv_v_mesh_init(bat_priv);
+ if (ret < 0) {
+ atomic_set(&bat_priv->mesh_state, BATADV_MESH_DEACTIVATING);
+ goto err_v;
+ }

ret = batadv_bla_init(bat_priv);
- if (ret < 0)
- goto err;
+ if (ret < 0) {
+ atomic_set(&bat_priv->mesh_state, BATADV_MESH_DEACTIVATING);
+ goto err_bla;
+ }

ret = batadv_dat_init(bat_priv);
- if (ret < 0)
- goto err;
+ if (ret < 0) {
+ atomic_set(&bat_priv->mesh_state, BATADV_MESH_DEACTIVATING);
+ goto err_dat;
+ }

ret = batadv_nc_mesh_init(bat_priv);
- if (ret < 0)
- goto err;
+ if (ret < 0) {
+ atomic_set(&bat_priv->mesh_state, BATADV_MESH_DEACTIVATING);
+ goto err_nc;
+ }

batadv_gw_init(bat_priv);
batadv_mcast_init(bat_priv);
@@ -219,8 +231,20 @@ int batadv_mesh_init(struct net_device *

return 0;

-err:
- batadv_mesh_free(soft_iface);
+err_nc:
+ batadv_dat_free(bat_priv);
+err_dat:
+ batadv_bla_free(bat_priv);
+err_bla:
+ batadv_v_mesh_free(bat_priv);
+err_v:
+ batadv_tt_free(bat_priv);
+err_tt:
+ batadv_originator_free(bat_priv);
+err_orig:
+ batadv_purge_outstanding_packets(bat_priv, NULL);
+ atomic_set(&bat_priv->mesh_state, BATADV_MESH_INACTIVE);
+
return ret;
}

--- a/net/batman-adv/network-coding.c
+++ b/net/batman-adv/network-coding.c
@@ -167,8 +167,10 @@ int batadv_nc_mesh_init(struct batadv_pr
&batadv_nc_coding_hash_lock_class_key);

bat_priv->nc.decoding_hash = batadv_hash_new(128);
- if (!bat_priv->nc.decoding_hash)
+ if (!bat_priv->nc.decoding_hash) {
+ batadv_hash_destroy(bat_priv->nc.coding_hash);
goto err;
+ }

batadv_hash_set_lock_class(bat_priv->nc.decoding_hash,
&batadv_nc_decoding_hash_lock_class_key);
--- a/net/batman-adv/translation-table.c
+++ b/net/batman-adv/translation-table.c
@@ -4413,8 +4413,10 @@ int batadv_tt_init(struct batadv_priv *b
return ret;

ret = batadv_tt_global_init(bat_priv);
- if (ret < 0)
+ if (ret < 0) {
+ batadv_tt_local_table_free(bat_priv);
return ret;
+ }

batadv_tvlv_handler_register(bat_priv, batadv_tt_tvlv_ogm_handler_v1,
batadv_tt_tvlv_unicast_handler_v1,