Commit 4fe267f0 authored Jun 27, 2024 by Tony Battersby Committed by Zhengchao Shao Jun 27, 2024

bonding: fix oops during rmmod

stable inclusion
from stable-v6.6.34
commit f07224c16678a8af54ddc059b3d2d51885d7f35e
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/IA8ADY
CVE: CVE-2024-39296

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=f07224c16678a8af54ddc059b3d2d51885d7f35e



---------------------------

commit a45835a0bb6ef7d5ddbc0714dd760de979cb6ece upstream.

"rmmod bonding" causes an oops ever since commit cc317ea3 ("bonding:
remove redundant NULL check in debugfs function").  Here are the relevant
functions being called:

bonding_exit()
  bond_destroy_debugfs()
    debugfs_remove_recursive(bonding_debug_root);
    bonding_debug_root = NULL; <--------- SET TO NULL HERE
  bond_netlink_fini()
    rtnl_link_unregister()
      __rtnl_link_unregister()
        unregister_netdevice_many_notify()
          bond_uninit()
            bond_debug_unregister()
              (commit removed check for bonding_debug_root == NULL)
              debugfs_remove()
              simple_recursive_removal()
                down_write() -> OOPS

However, reverting the bad commit does not solve the problem completely
because the original code contains a race that could cause the same
oops, although it was much less likely to be triggered unintentionally:

CPU1
  rmmod bonding
    bonding_exit()
      bond_destroy_debugfs()
        debugfs_remove_recursive(bonding_debug_root);

CPU2
  echo -bond0 > /sys/class/net/bonding_masters
    bond_uninit()
      bond_debug_unregister()
        if (!bonding_debug_root)

CPU1
        bonding_debug_root = NULL;

So do NOT revert the bad commit (since the removed checks were racy
anyway), and instead change the order of actions taken during module
removal.  The same oops can also happen if there is an error during
module init, so apply the same fix there.

Fixes: cc317ea3 ("bonding: remove redundant NULL check in debugfs function")
Cc: stable@vger.kernel.org
Signed-off-by: Tony Battersby <tonyb@cybernetics.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Acked-by: Jay Vosburgh <jay.vosburgh@canonical.com>
Link: https://lore.kernel.org/r/641f914f-3216-4eeb-87dd-91b78aa97773@cybernetics.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Conflicts:
	drivers/net/bonding/bond_main.c
[The conflict occurs because the commit 6263012c("anolis: bond:
broadcast ARP or ND messages to all slaves") is not merged into mainline]
Signed-off-by: Zhengchao Shao <shaozhengchao@huawei.com>

parent 43499e79

drivers/net/bonding/bond_main.c

+7 −4

Original line number	Diff line number	Diff line
		@@ -6526,15 +6526,16 @@ static int __init bonding_init(void)
		if (res)
		goto out;

		bond_create_debugfs();

		res = register_pernet_subsys(&bond_net_ops);
		if (res)
		goto out;
		goto err_net_ops;

		res = bond_netlink_init();
		if (res)
		goto err_link;

		bond_create_debugfs();
		bond_create_sysctl();

		for (i = 0; i < max_bonds; i++) {
		@@ -6551,11 +6552,12 @@ static int __init bonding_init(void)
		out:
		return res;
		err:
		bond_destroy_debugfs();
		bond_destroy_sysctl();
		bond_netlink_fini();
		err_link:
		unregister_pernet_subsys(&bond_net_ops);
		err_net_ops:
		bond_destroy_debugfs();
		goto out;

		}
		@@ -6564,12 +6566,13 @@ static void __exit bonding_exit(void)
		{
		unregister_netdevice_notifier(&bond_netdev_notifier);

		bond_destroy_debugfs();
		bond_destroy_sysctl();

		bond_netlink_fini();
		unregister_pernet_subsys(&bond_net_ops);

		bond_destroy_debugfs();

		#ifdef CONFIG_NET_POLL_CONTROLLER
		/* Make sure we don't have an imbalance on our netpoll blocking */
		WARN_ON(atomic_read(&netpoll_block_tx));