drbd: Fix five use after free bugs in get_initial_state

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>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/drivers/block/drbd/drbd_int.h b/drivers/block/drbd/drbd_int.h
index 4b55e864a0a348d2252a2fb2fffd57e5240d4bc3..4d3efaa20b7bffca3c9cae661a417d14bf2458f3 100644 (file)
--- 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 02030c9c4d3b16d55e0fc857dfe80b53472ac021..b7216c186ba4d731c6212f30751b435805a9fcb5 100644 (file)
--- 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 @@ 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;
@@ -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 @@ next:
                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 b8a27818ab3f83ae1139a30009c0b5e299a3f0b0..4ee11aef6672b8992a19f262284043a912cf5157 100644 (file)
--- 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 ba80f612d6abbc185dc9a73ee5e72dbb86932b8f..d5b0479bc9a6649e6bd423d5793861e5fa0022f6 100644 (file)
--- 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);