The patch below does not apply to the 5.15-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y git checkout FETCH_HEAD git cherry-pick -x 1a83f4a7c156fa6bbd6b530e89fa3270bf3d9d1b # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2023102011-rubble-require-8127@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 1a83f4a7c156fa6bbd6b530e89fa3270bf3d9d1b Mon Sep 17 00:00:00 2001 From: Jakub Kicinski kuba@kernel.org Date: Tue, 17 Oct 2023 18:38:15 -0700 Subject: [PATCH] net: avoid UAF on deleted altname

Altnames are accessed under RCU (dev_get_by_name_rcu()) but freed by kfree() with no synchronization point.

Each node has one or two allocations (node and a variable-size name, sometimes the name is netdev->name). Adding rcu_heads here is a bit tedious. Besides most code which unlists the names already has rcu barriers - so take the simpler approach of adding synchronize_rcu(). Note that the one on the unregistration path (which matters more) is removed by the next fix.

Fixes: ff92741270bf ("net: introduce name_node struct to be used in hashlist") Reviewed-by: Jiri Pirko jiri@nvidia.com Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Paolo Abeni pabeni@redhat.com

diff --git a/net/core/dev.c b/net/core/dev.c index ae557193b77c..559705aeefe4 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -345,7 +345,6 @@ int netdev_name_node_alt_create(struct net_device *dev, const char *name) static void __netdev_name_node_alt_destroy(struct netdev_name_node *name_node) { list_del(&name_node->list); - netdev_name_node_del(name_node); kfree(name_node->name); netdev_name_node_free(name_node); } @@ -364,6 +363,8 @@ int netdev_name_node_alt_destroy(struct net_device *dev, const char *name) if (name_node == dev->name_node || name_node->dev != dev) return -EINVAL;

+ netdev_name_node_del(name_node); + synchronize_rcu(); __netdev_name_node_alt_destroy(name_node);

return 0; @@ -10941,6 +10942,7 @@ void unregister_netdevice_many_notify(struct list_head *head, synchronize_net();

list_for_each_entry(dev, head, unreg_list) { + struct netdev_name_node *name_node; struct sk_buff *skb = NULL;

/* Shutdown queueing discipline. */ @@ -10968,6 +10970,9 @@ void unregister_netdevice_many_notify(struct list_head *head, dev_uc_flush(dev); dev_mc_flush(dev);

+ netdev_for_each_altname(dev, name_node) + netdev_name_node_del(name_node); + synchronize_rcu(); netdev_name_node_alt_flush(dev); netdev_name_node_free(dev->name_node);