[PATCH 0/3] DRBD fixes for Linux 5.18

[PATCH 0/3] DRBD fixes for Linux 5.18

[Christoph Böhmwalder]

Assortment of more relevant fixes for DRBD to go into 5.18.

Christoph Böhmwalder (1):
  drbd: set QUEUE_FLAG_STABLE_WRITES

Lv Yunlong (1):
  drbd: Fix five use after free bugs in get_initial_state

Xiaomeng Tong (1):
  drbd: fix an invalid memory access caused by incorrect use of list
    iterator

 drivers/block/drbd/drbd_int.h          |  8 ++---
 drivers/block/drbd/drbd_main.c         |  7 ++---
 drivers/block/drbd/drbd_nl.c           | 41 ++++++++++++++++----------
 drivers/block/drbd/drbd_state.c        | 18 +++++------
 drivers/block/drbd/drbd_state_change.h |  8 ++---
 5 files changed, 45 insertions(+), 37 deletions(-)

-- 
2.35.1

[PATCH 1/3] drbd: Fix five use after free bugs in get_initial_state

[Christoph Böhmwalder]

From: Lv Yunlong <lyl2019@mail.ustc.edu.cn>

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.

v2 reports a compilation warning. This v3 fixed this warning and built
successfully in my local environment with no additional warnings.
v2: https://lore.kernel.org/patchwork/patch/1435218/

Fixes: a29728463b254 ("drbd: Backport the "events2" command")
Signed-off-by: Lv Yunlong <lyl2019@mail.ustc.edu.cn>
Reviewed-by: Christoph Böhmwalder <christoph.boehmwalder@linbit.com>
---
 drivers/block/drbd/drbd_int.h          |  8 ++---
 drivers/block/drbd/drbd_nl.c           | 41 ++++++++++++++++----------
 drivers/block/drbd/drbd_state.c        | 18 +++++------
 drivers/block/drbd/drbd_state_change.h |  8 ++---
 4 files changed, 42 insertions(+), 33 deletions(-)

diff --git a/drivers/block/drbd/drbd_int.h b/drivers/block/drbd/drbd_int.h
index 4b55e864a0a3..4d3efaa20b7b 100644
--- a/drivers/block/drbd/drbd_int.h
+++ b/drivers/block/drbd/drbd_int.h
@@ -1638,22 +1638,22 @@ struct sib_info {
 };
 void drbd_bcast_event(struct drbd_device *device, const struct sib_info *sib);
 
-extern void notify_resource_state(struct sk_buff *,
+extern int notify_resource_state(struct sk_buff *,
 				  unsigned int,
 				  struct drbd_resource *,
 				  struct 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 *,
diff --git a/drivers/block/drbd/drbd_nl.c b/drivers/block/drbd/drbd_nl.c
index 02030c9c4d3b..b7216c186ba4 100644
--- a/drivers/block/drbd/drbd_nl.c
+++ b/drivers/block/drbd/drbd_nl.c
@@ -4549,7 +4549,7 @@ 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,
@@ -4591,16 +4591,17 @@ 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,
@@ -4640,16 +4641,17 @@ 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;
 }
 
-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,
@@ -4689,16 +4691,17 @@ 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,
@@ -4739,13 +4742,14 @@ 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 notify_helper(enum drbd_notification_type type,
@@ -4796,7 +4800,7 @@ void notify_helper(enum drbd_notification_type type,
 		 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;
@@ -4810,11 +4814,12 @@ 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)
@@ -4841,6 +4846,7 @@ 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 chage
@@ -4849,32 +4855,32 @@ 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->resource,
+		err = notify_resource_state_change(skb, seq, state_change->resource,
 					     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;
 	}
 	n -= state_change->n_connections;
 	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;
 	}
@@ -4889,7 +4895,10 @@ static int get_initial_state(struct sk_buff *skb, struct netlink_callback *cb)
 		cb->args[4] = 0;
 	}
 out:
-	return skb->len;
+	if (err)
+		return err;
+	else
+		return skb->len;
 }
 
 int drbd_adm_get_initial_state(struct sk_buff *skb, struct netlink_callback *cb)
diff --git a/drivers/block/drbd/drbd_state.c b/drivers/block/drbd/drbd_state.c
index b8a27818ab3f..4ee11aef6672 100644
--- a/drivers/block/drbd/drbd_state.c
+++ b/drivers/block/drbd/drbd_state.c
@@ -1537,7 +1537,7 @@ int drbd_bitmap_io_from_worker(struct drbd_device *device,
 	return rv;
 }
 
-void notify_resource_state_change(struct sk_buff *skb,
+int notify_resource_state_change(struct sk_buff *skb,
 				  unsigned int seq,
 				  struct drbd_resource_state_change *resource_state_change,
 				  enum drbd_notification_type type)
@@ -1550,10 +1550,10 @@ void notify_resource_state_change(struct sk_buff *skb,
 		.res_susp_fen = resource_state_change->susp_fen[NEW],
 	};
 
-	notify_resource_state(skb, seq, resource, &resource_info, type);
+	return notify_resource_state(skb, seq, resource, &resource_info, 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)
@@ -1564,10 +1564,10 @@ 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)
@@ -1577,10 +1577,10 @@ void notify_device_state_change(struct sk_buff *skb,
 		.dev_disk_state = device_state_change->disk_state[NEW],
 	};
 
-	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 *p,
 				     enum drbd_notification_type type)
@@ -1594,7 +1594,7 @@ void notify_peer_device_state_change(struct sk_buff *skb,
 		.peer_resync_susp_dependency = p->resync_susp_dependency[NEW],
 	};
 
-	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 broadcast_state_change(struct drbd_state_change *state_change)
@@ -1602,7 +1602,7 @@ static void broadcast_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/drivers/block/drbd/drbd_state_change.h b/drivers/block/drbd/drbd_state_change.h
index ba80f612d6ab..d5b0479bc9a6 100644
--- a/drivers/block/drbd/drbd_state_change.h
+++ b/drivers/block/drbd/drbd_state_change.h
@@ -44,19 +44,19 @@ extern struct drbd_state_change *remember_old_state(struct drbd_resource *, gfp_
 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_resource_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);
-- 
2.35.1

[PATCH 2/3] drbd: fix an invalid memory access caused by incorrect use of list iterator

[Christoph Böhmwalder]

From: Xiaomeng Tong <xiam0nd.tong@gmail.com>

The bug is here:
	idr_remove(&connection->peer_devices, vnr);

If the previous for_each_connection() don't exit early (no goto hit
inside the loop), the iterator 'connection' after the loop will be a
bogus pointer to an invalid structure object containing the HEAD
(&resource->connections). As a result, the use of 'connection' above
will lead to a invalid memory access (including a possible invalid free
as idr_remove could call free_layer).

The original intention should have been to remove all peer_devices,
but the following lines have already done the work. So just remove
this line and the unneeded label, to fix this bug.

Cc: stable@vger.kernel.org
Fixes: c06ece6ba6f1b ("drbd: Turn connection->volumes into connection->peer_devices")
Signed-off-by: Xiaomeng Tong <xiam0nd.tong@gmail.com>
Reviewed-by: Christoph Böhmwalder <christoph.boehmwalder@linbit.com>
Reviewed-by: Lars Ellenberg <lars.ellenberg@linbit.com>
---
 drivers/block/drbd/drbd_main.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/drivers/block/drbd/drbd_main.c b/drivers/block/drbd/drbd_main.c
index 9676a1d214bc..d6dfa286ddb3 100644
--- a/drivers/block/drbd/drbd_main.c
+++ b/drivers/block/drbd/drbd_main.c
@@ -2773,12 +2773,12 @@ enum drbd_ret_code drbd_create_device(struct drbd_config_context *adm_ctx, unsig
 
 	if (init_submitter(device)) {
 		err = ERR_NOMEM;
-		goto out_idr_remove_vol;
+		goto out_idr_remove_from_resource;
 	}
 
 	err = add_disk(disk);
 	if (err)
-		goto out_idr_remove_vol;
+		goto out_idr_remove_from_resource;
 
 	/* inherit the connection state */
 	device->state.conn = first_connection(resource)->cstate;
@@ -2792,8 +2792,6 @@ enum drbd_ret_code drbd_create_device(struct drbd_config_context *adm_ctx, unsig
 	drbd_debugfs_device_add(device);
 	return NO_ERROR;
 
-out_idr_remove_vol:
-	idr_remove(&connection->peer_devices, vnr);
 out_idr_remove_from_resource:
 	for_each_connection(connection, resource) {
 		peer_device = idr_remove(&connection->peer_devices, vnr);
-- 
2.35.1

[PATCH 3/3] drbd: set QUEUE_FLAG_STABLE_WRITES

[Christoph Böhmwalder]

From: Christoph Böhmwalder <christoph@boehmwalder.at>

We want our pages not to change while they are being written.

Signed-off-by: Christoph Böhmwalder <christoph.boehmwalder@linbit.com>
---
 drivers/block/drbd/drbd_main.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/block/drbd/drbd_main.c b/drivers/block/drbd/drbd_main.c
index d6dfa286ddb3..4b0b25cc916e 100644
--- a/drivers/block/drbd/drbd_main.c
+++ b/drivers/block/drbd/drbd_main.c
@@ -2719,6 +2719,7 @@ enum drbd_ret_code drbd_create_device(struct drbd_config_context *adm_ctx, unsig
 	sprintf(disk->disk_name, "drbd%d", minor);
 	disk->private_data = device;
 
+	blk_queue_flag_set(QUEUE_FLAG_STABLE_WRITES, disk->queue);
 	blk_queue_write_cache(disk->queue, true, true);
 	/* Setting the max_hw_sectors to an odd value of 8kibyte here
 	   This triggers a max_bio_size message upon first attach or connect */
-- 
2.35.1

Re: [PATCH 0/3] DRBD fixes for Linux 5.18

[Jens Axboe]

On 4/6/22 1:04 PM, Christoph Böhmwalder wrote:
> Assortment of more relevant fixes for DRBD to go into 5.18.
> 
> Christoph Böhmwalder (1):
>   drbd: set QUEUE_FLAG_STABLE_WRITES
> 
> Lv Yunlong (1):
>   drbd: Fix five use after free bugs in get_initial_state
> 
> Xiaomeng Tong (1):
>   drbd: fix an invalid memory access caused by incorrect use of list
>     iterator
> 
>  drivers/block/drbd/drbd_int.h          |  8 ++---
>  drivers/block/drbd/drbd_main.c         |  7 ++---
>  drivers/block/drbd/drbd_nl.c           | 41 ++++++++++++++++----------
>  drivers/block/drbd/drbd_state.c        | 18 +++++------
>  drivers/block/drbd/drbd_state_change.h |  8 ++---
>  5 files changed, 45 insertions(+), 37 deletions(-)

Applied, thanks.

-- 
Jens Axboe

Re: [PATCH 3/3] drbd: set QUEUE_FLAG_STABLE_WRITES

[Christoph Hellwig]

On Wed, Apr 06, 2022 at 09:04:45PM +0200, Christoph Böhmwalder wrote:
> From: Christoph Böhmwalder <christoph@boehmwalder.at>
> 
> We want our pages not to change while they are being written.

Please document the _why_.  A commit like that will leave everyone
looking at this code in the future rather puzzled.