devlink: Fix list access without lock while reading region
While finding the devlink device during region reading,
devlink device list is accessed and devlink device is
returned without holding a lock. This could lead to use-after-free
accesses.
While at it, add lockdep assert to ensure that all future callers hold
the lock when calling devlink_get_from_attrs().
Fixes: 4e54795a27f5 ("devlink: Add support for region snapshot read command")
Signed-off-by: Parav Pandit <parav@mellanox.com>
Acked-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/core/devlink.c b/net/core/devlink.c
index 312084f..1d7502a5 100644
--- a/net/core/devlink.c
+++ b/net/core/devlink.c
@@ -116,6 +116,8 @@ static struct devlink *devlink_get_from_attrs(struct net *net,
busname = nla_data(attrs[DEVLINK_ATTR_BUS_NAME]);
devname = nla_data(attrs[DEVLINK_ATTR_DEV_NAME]);
+ lockdep_assert_held(&devlink_mutex);
+
list_for_each_entry(devlink, &devlink_list, list) {
if (strcmp(devlink->dev->bus->name, busname) == 0 &&
strcmp(dev_name(devlink->dev), devname) == 0 &&
@@ -3645,13 +3647,13 @@ static int devlink_nl_cmd_region_read_dumpit(struct sk_buff *skb,
if (err)
goto out_free;
+ mutex_lock(&devlink_mutex);
devlink = devlink_get_from_attrs(sock_net(cb->skb->sk), attrs);
if (IS_ERR(devlink)) {
err = PTR_ERR(devlink);
- goto out_free;
+ goto out_dev;
}
- mutex_lock(&devlink_mutex);
mutex_lock(&devlink->lock);
if (!attrs[DEVLINK_ATTR_REGION_NAME] ||
@@ -3729,6 +3731,7 @@ static int devlink_nl_cmd_region_read_dumpit(struct sk_buff *skb,
genlmsg_cancel(skb, hdr);
out_unlock:
mutex_unlock(&devlink->lock);
+out_dev:
mutex_unlock(&devlink_mutex);
out_free:
kfree(attrs);
