FAILED: patch "[PATCH] net: batman-adv: fix error handling" failed to apply to 4.4-stable tree

The patch below does not apply to the 4.4-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 6f68cd634856f8ca93bafd623ba5357e0f648c68 Mon Sep 17 00:00:00 2001
From: Pavel Skripkin <[email protected]>
Date: Sun, 24 Oct 2021 16:13:56 +0300
Subject: [PATCH] net: batman-adv: fix error handling

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.

index 1669744304c5..17687848daec 100644
@@ -1560,10 +1560,14 @@ int batadv_bla_init(struct batadv_priv *bat_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);

index 9f06132e007d..0a7f1d36a6a8 100644
@@ -152,8 +152,10 @@ int batadv_nc_mesh_init(struct batadv_priv *bat_priv)
 				   &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);

index e0b3dace2020..4b7ad6684bc4 100644
@@ -4162,8 +4162,10 @@ int batadv_tt_init(struct batadv_priv *bat_priv)
 		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,