[PATCH v3] drbd: Fix five use after free bugs in get_initial_state

From: Lv Yunlong
Date: Tue May 25 2021 - 02:59:43 EST

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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@xxxxxxxxxxxxxxxx>
---
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 5d9181382ce1..0a5766a2f161 100644
--- a/drivers/block/drbd/drbd_int.h
+++ b/drivers/block/drbd/drbd_int.h
@@ -1642,22 +1642,22 @@ 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 e7d0e637e632..18c4fea028e1 100644
--- a/drivers/block/drbd/drbd_nl.c
+++ b/drivers/block/drbd/drbd_nl.c
@@ -4617,7 +4617,7 @@ 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,
@@ -4659,16 +4659,17 @@ 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,
@@ -4708,16 +4709,17 @@ 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,
@@ -4757,16 +4759,17 @@ 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,
@@ -4807,13 +4810,14 @@ 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,
@@ -4864,7 +4868,7 @@ 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;
@@ -4878,11 +4882,12 @@ 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)
@@ -4909,6 +4914,7 @@ 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
@@ -4917,32 +4923,32 @@ 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;
}
@@ -4957,7 +4963,10 @@ 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);
--
2.25.1

Next message: Jin, Yao: "Re: [PATCH v1 4/5] perf mem: Support record for hybrid platform"
Previous message: Takashi Iwai: "Re: [PATCH] sound/oss/dmasound: Remove superfluous "break""
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