drbd/bsc-1206791-07-drbd-fix-use-after-free-bugs-in-get_initial_state.patch

From 2573d91be862ed65781c4a37dcaaa051a905a48a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Christoph=20B=C3=B6hmwalder?=
 <christoph.boehmwalder@linbit.com>
Date: Wed, 5 Oct 2022 13:36:18 +0200
Subject: [PATCH] drbd: fix use-after-free bugs in get_initial_state

See upstream commit aadb22ba2f65 ("drbd: Fix five use after free bugs
in get_initial_state").

Original message:

In get_initial_state, it calls notify_initial_state_done(skb,..) if
cb->args[5]==1. If genlmsg_put() failed in notify_initial_state_done(),
the skb will be freed by nlmsg_free(skb).
Then get_initial_state will goto out and the freed skb will be used by
return value skb->len, which is a uaf bug.

What's worse, the same problem goes even further: skb can also be
freed in the notify_*_state_change -> notify_*_state calls below.
Thus 4 additional uaf bugs happened.

My patch lets the problem callee functions: notify_initial_state_done
and notify_*_state_change return an error code if errors happen.
So that the error codes could be propagated and the uaf bugs can be avoid.
---
 drbd/drbd_int.h          | 10 ++++----
 drbd/drbd_nl.c           | 51 ++++++++++++++++++++++++----------------
 drbd/drbd_state.c        | 18 +++++++-------
 drbd/drbd_state_change.h |  8 +++----
 4 files changed, 49 insertions(+), 38 deletions(-)

diff --git a/drbd/drbd_int.h b/drbd/drbd_int.h
index fcde3b96bd6a..4bf2c6dde93d 100644
--- a/drbd/drbd_int.h
+++ b/drbd/drbd_int.h
@@ -2154,30 +2154,30 @@ extern int drbd_al_initialize(struct drbd_device *, void *);
 extern struct mutex notification_mutex;
 extern atomic_t drbd_genl_seq;
 
-extern void notify_resource_state(struct sk_buff *,
+extern int notify_resource_state(struct sk_buff *,
 				  unsigned int,
 				  struct drbd_resource *,
 				  struct resource_info *,
 				  struct rename_resource_info *,
 				  enum drbd_notification_type);
-extern void notify_device_state(struct sk_buff *,
+extern int notify_device_state(struct sk_buff *,
 				unsigned int,
 				struct drbd_device *,
 				struct device_info *,
 				enum drbd_notification_type);
-extern void notify_connection_state(struct sk_buff *,
+extern int notify_connection_state(struct sk_buff *,
 				    unsigned int,
 				    struct drbd_connection *,
 				    struct connection_info *,
 				    enum drbd_notification_type);
-extern void notify_peer_device_state(struct sk_buff *,
+extern int notify_peer_device_state(struct sk_buff *,
 				     unsigned int,
 				     struct drbd_peer_device *,
 				     struct peer_device_info *,
 				     enum drbd_notification_type);
 extern void notify_helper(enum drbd_notification_type, struct drbd_device *,
 			  struct drbd_connection *, const char *, int);
-extern void notify_path(struct drbd_connection *, struct drbd_path *,
+extern int notify_path(struct drbd_connection *, struct drbd_path *,
 			enum drbd_notification_type);
 extern void drbd_broadcast_peer_device_state(struct drbd_peer_device *);
 
diff --git a/drbd/drbd_nl.c b/drbd/drbd_nl.c
index 3dee5a1ab2eb..4418d143e09f 100644
--- a/drbd/drbd_nl.c
+++ b/drbd/drbd_nl.c
@@ -6492,7 +6492,7 @@ static int nla_put_notification_header(struct sk_buff *msg,
 	return drbd_notification_header_to_skb(msg, &nh, true);
 }
 
-void notify_resource_state(struct sk_buff *skb,
+int notify_resource_state(struct sk_buff *skb,
 			   unsigned int seq,
 			   struct drbd_resource *resource,
 			   struct resource_info *resource_info,
@@ -6546,16 +6546,17 @@ void notify_resource_state(struct sk_buff *skb,
 		if (err && err != -ESRCH)
 			goto failed;
 	}
-	return;
+	return 0;
 
 nla_put_failure:
 	nlmsg_free(skb);
 failed:
 	drbd_err(resource, "Error %d while broadcasting event. Event seq:%u\n",
 			err, seq);
+	return err;
 }
 
-void notify_device_state(struct sk_buff *skb,
+int notify_device_state(struct sk_buff *skb,
 			 unsigned int seq,
 			 struct drbd_device *device,
 			 struct device_info *device_info,
@@ -6595,17 +6596,18 @@ void notify_device_state(struct sk_buff *skb,
 		if (err && err != -ESRCH)
 			goto failed;
 	}
-	return;
+	return 0;
 
 nla_put_failure:
 	nlmsg_free(skb);
 failed:
 	drbd_err(device, "Error %d while broadcasting event. Event seq:%u\n",
 		 err, seq);
+	return err;
 }
 
 /* open coded path_parms_to_skb() iterating of the list */
-void notify_connection_state(struct sk_buff *skb,
+int notify_connection_state(struct sk_buff *skb,
 			     unsigned int seq,
 			     struct drbd_connection *connection,
 			     struct connection_info *connection_info,
@@ -6646,16 +6648,17 @@ void notify_connection_state(struct sk_buff *skb,
 		if (err && err != -ESRCH)
 			goto failed;
 	}
-	return;
+	return 0;
 
 nla_put_failure:
 	nlmsg_free(skb);
 failed:
 	drbd_err(connection, "Error %d while broadcasting event. Event seq:%u\n",
 		 err, seq);
+	return err;
 }
 
-void notify_peer_device_state(struct sk_buff *skb,
+int notify_peer_device_state(struct sk_buff *skb,
 			      unsigned int seq,
 			      struct drbd_peer_device *peer_device,
 			      struct peer_device_info *peer_device_info,
@@ -6696,13 +6699,14 @@ void notify_peer_device_state(struct sk_buff *skb,
 		if (err && err != -ESRCH)
 			goto failed;
 	}
-	return;
+	return 0;
 
 nla_put_failure:
 	nlmsg_free(skb);
 failed:
 	drbd_err(peer_device, "Error %d while broadcasting event. Event seq:%u\n",
 		 err, seq);
+	return err;
 }
 
 void drbd_broadcast_peer_device_state(struct drbd_peer_device *peer_device)
@@ -6714,7 +6718,7 @@ void drbd_broadcast_peer_device_state(struct drbd_peer_device *peer_device)
 	mutex_unlock(&notification_mutex);
 }
 
-void notify_path_state(struct sk_buff *skb,
+int notify_path_state(struct sk_buff *skb,
 		       unsigned int seq,
 		       /* until we have a backpointer in drbd_path, we need an explicit connection: */
 		       struct drbd_connection *connection,
@@ -6754,7 +6758,7 @@ void notify_path_state(struct sk_buff *skb,
 		if (err && err != -ESRCH)
 			goto failed;
 	}
-	return;
+	return 0;
 
 nla_put_failure:
 	nlmsg_free(skb);
@@ -6762,16 +6766,19 @@ failed:
 	/* FIXME add path specifics to our drbd_polymorph_printk.h */
 	drbd_err(connection, "path: Error %d while broadcasting event. Event seq:%u\n",
 		 err, seq);
+	return err;
 }
 
-void notify_path(struct drbd_connection *connection, struct drbd_path *path, enum drbd_notification_type type)
+int notify_path(struct drbd_connection *connection, struct drbd_path *path, enum drbd_notification_type type)
 {
 	struct drbd_path_info path_info;
+	int err;
 
 	path_info.path_established = path->established;
 	mutex_lock(&notification_mutex);
-	notify_path_state(NULL, 0, connection, path, &path_info, type);
+	err = notify_path_state(NULL, 0, connection, path, &path_info, type);
 	mutex_unlock(&notification_mutex);
+	return err;
 
 }
 
@@ -6823,7 +6830,7 @@ fail:
 		 err, seq);
 }
 
-static void notify_initial_state_done(struct sk_buff *skb, unsigned int seq)
+static int notify_initial_state_done(struct sk_buff *skb, unsigned int seq)
 {
 	struct drbd_genlmsghdr *dh;
 	int err;
@@ -6837,11 +6844,12 @@ static void notify_initial_state_done(struct sk_buff *skb, unsigned int seq)
 	if (nla_put_notification_header(skb, NOTIFY_EXISTS))
 		goto nla_put_failure;
 	genlmsg_end(skb, dh);
-	return;
+	return 0;
 
 nla_put_failure:
 	nlmsg_free(skb);
 	pr_err("Error %d sending event. Event seq:%u\n", err, seq);
+	return err;
 }
 
 static void free_state_changes(struct list_head *list)
@@ -6869,6 +6877,7 @@ static int get_initial_state(struct sk_buff *skb, struct netlink_callback *cb)
 	unsigned int seq = cb->args[2];
 	unsigned int n;
 	enum drbd_notification_type flags = 0;
+	int err = 0;
 
 	/* There is no need for taking notification_mutex here: it doesn't
 	   matter if the initial state events mix with later state change
@@ -6877,20 +6886,20 @@ static int get_initial_state(struct sk_buff *skb, struct netlink_callback *cb)
 
 	cb->args[5]--;
 	if (cb->args[5] == 1) {
-		notify_initial_state_done(skb, seq);
+		err = notify_initial_state_done(skb, seq);
 		goto out;
 	}
 	n = cb->args[4]++;
 	if (cb->args[4] < cb->args[3])
 		flags |= NOTIFY_CONTINUES;
 	if (n < 1) {
-		notify_resource_state_change(skb, seq, state_change,
+		err = notify_resource_state_change(skb, seq, state_change,
 					     NOTIFY_EXISTS | flags);
 		goto next;
 	}
 	n--;
 	if (n < state_change->n_connections) {
-		notify_connection_state_change(skb, seq, &state_change->connections[n],
+		err = notify_connection_state_change(skb, seq, &state_change->connections[n],
 					       NOTIFY_EXISTS | flags);
 		goto next;
 	}
@@ -6900,7 +6909,7 @@ static int get_initial_state(struct sk_buff *skb, struct netlink_callback *cb)
 		struct drbd_path_info path_info;
 
 		path_info.path_established = path_state->path_established;
-		notify_path_state(skb, seq,
+		err = notify_path_state(skb, seq,
 				path_state->connection,
 				path_state->path,
 				&path_info, NOTIFY_EXISTS | flags);
@@ -6908,13 +6917,13 @@ static int get_initial_state(struct sk_buff *skb, struct netlink_callback *cb)
 	}
 	n -= state_change->n_paths;
 	if (n < state_change->n_devices) {
-		notify_device_state_change(skb, seq, &state_change->devices[n],
+		err = notify_device_state_change(skb, seq, &state_change->devices[n],
 					   NOTIFY_EXISTS | flags);
 		goto next;
 	}
 	n -= state_change->n_devices;
 	if (n < state_change->n_devices * state_change->n_connections) {
-		notify_peer_device_state_change(skb, seq, &state_change->peer_devices[n],
+		err = notify_peer_device_state_change(skb, seq, &state_change->peer_devices[n],
 						NOTIFY_EXISTS | flags);
 		goto next;
 	}
@@ -6930,6 +6939,8 @@ next:
 		cb->args[4] = 0;
 	}
 out:
+	if (err)
+		return err;
 	return skb->len;
 }
 
diff --git a/drbd/drbd_state.c b/drbd/drbd_state.c
index de53fa7a21f1..cec88b18852f 100644
--- a/drbd/drbd_state.c
+++ b/drbd/drbd_state.c
@@ -3062,7 +3062,7 @@ static union drbd_state state_change_word(struct drbd_state_change *state_change
 	return state;
 }
 
-void notify_resource_state_change(struct sk_buff *skb,
+int notify_resource_state_change(struct sk_buff *skb,
 				  unsigned int seq,
 				  struct drbd_state_change *state_change,
 				  enum drbd_notification_type type)
@@ -3079,10 +3079,10 @@ void notify_resource_state_change(struct sk_buff *skb,
 		.res_susp_quorum = state_change_is_susp_quorum(state_change, NEW),
 	};
 
-	notify_resource_state(skb, seq, resource, &resource_info, NULL, type);
+	return notify_resource_state(skb, seq, resource, &resource_info, NULL, type);
 }
 
-void notify_connection_state_change(struct sk_buff *skb,
+int notify_connection_state_change(struct sk_buff *skb,
 				    unsigned int seq,
 				    struct drbd_connection_state_change *connection_state_change,
 				    enum drbd_notification_type type)
@@ -3093,10 +3093,10 @@ void notify_connection_state_change(struct sk_buff *skb,
 		.conn_role = connection_state_change->peer_role[NEW],
 	};
 
-	notify_connection_state(skb, seq, connection, &connection_info, type);
+	return notify_connection_state(skb, seq, connection, &connection_info, type);
 }
 
-void notify_device_state_change(struct sk_buff *skb,
+int notify_device_state_change(struct sk_buff *skb,
 				unsigned int seq,
 				struct drbd_device_state_change *device_state_change,
 				enum drbd_notification_type type)
@@ -3105,10 +3105,10 @@ void notify_device_state_change(struct sk_buff *skb,
 	struct device_info device_info;
 	device_state_change_to_info(&device_info, device_state_change);
 
-	notify_device_state(skb, seq, device, &device_info, type);
+	return notify_device_state(skb, seq, device, &device_info, type);
 }
 
-void notify_peer_device_state_change(struct sk_buff *skb,
+int notify_peer_device_state_change(struct sk_buff *skb,
 				     unsigned int seq,
 				     struct drbd_peer_device_state_change *state_change,
 				     enum drbd_notification_type type)
@@ -3117,7 +3117,7 @@ void notify_peer_device_state_change(struct sk_buff *skb,
 	struct peer_device_info peer_device_info;
 	peer_device_state_change_to_info(&peer_device_info, state_change);
 
-	notify_peer_device_state(skb, seq, peer_device, &peer_device_info, type);
+	return notify_peer_device_state(skb, seq, peer_device, &peer_device_info, type);
 }
 
 static void notify_state_change(struct drbd_state_change *state_change)
@@ -3125,7 +3125,7 @@ static void notify_state_change(struct drbd_state_change *state_change)
 	struct drbd_resource_state_change *resource_state_change = &state_change->resource[0];
 	bool resource_state_has_changed;
 	unsigned int n_device, n_connection, n_peer_device, n_peer_devices;
-	void (*last_func)(struct sk_buff *, unsigned int, void *,
+	int (*last_func)(struct sk_buff *, unsigned int, void *,
 			  enum drbd_notification_type) = NULL;
 	void *last_arg = NULL;
 
diff --git a/drbd/drbd_state_change.h b/drbd/drbd_state_change.h
index e60ec1b8ee6e..df23977462c1 100644
--- a/drbd/drbd_state_change.h
+++ b/drbd/drbd_state_change.h
@@ -66,19 +66,19 @@ extern struct drbd_state_change *remember_state_change(struct drbd_resource *, g
 extern void copy_old_to_new_state_change(struct drbd_state_change *);
 extern void forget_state_change(struct drbd_state_change *);
 
-extern void notify_resource_state_change(struct sk_buff *,
+extern int notify_resource_state_change(struct sk_buff *,
 					 unsigned int,
 					 struct drbd_state_change *,
 					 enum drbd_notification_type type);
-extern void notify_connection_state_change(struct sk_buff *,
+extern int notify_connection_state_change(struct sk_buff *,
 					   unsigned int,
 					   struct drbd_connection_state_change *,
 					   enum drbd_notification_type type);
-extern void notify_device_state_change(struct sk_buff *,
+extern int notify_device_state_change(struct sk_buff *,
 				       unsigned int,
 				       struct drbd_device_state_change *,
 				       enum drbd_notification_type type);
-extern void notify_peer_device_state_change(struct sk_buff *,
+extern int notify_peer_device_state_change(struct sk_buff *,
 					    unsigned int,
 					    struct drbd_peer_device_state_change *,
 					    enum drbd_notification_type type);
-- 
2.26.2