Patch "net: dsa: don't leak tagger-owned storage on switch driver unbind" has been added to the 6.0-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    net: dsa: don't leak tagger-owned storage on switch driver unbind

to the 6.0-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     net-dsa-don-t-leak-tagger-owned-storage-on-switch-dr.patch
and it can be found in the queue-6.0 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 529d959e5a938c3e2acb7aaa5126231ced047677
Author: Vladimir Oltean <vladimir.oltean@xxxxxxx>
Date:   Mon Nov 14 16:35:51 2022 +0200

    net: dsa: don't leak tagger-owned storage on switch driver unbind
    
    [ Upstream commit 4e0c19fcb8b5323716140fa82b79aa9f60e60407 ]
    
    In the initial commit dc452a471dba ("net: dsa: introduce tagger-owned
    storage for private and shared data"), we had a call to
    tag_ops->disconnect(dst) issued from dsa_tree_free(), which is called at
    tree teardown time.
    
    There were problems with connecting to a switch tree as a whole, so this
    got reworked to connecting to individual switches within the tree. In
    this process, tag_ops->disconnect(ds) was made to be called only from
    switch.c (cross-chip notifiers emitted as a result of dynamic tag proto
    changes), but the normal driver teardown code path wasn't replaced with
    anything.
    
    Solve this problem by adding a function that does the opposite of
    dsa_switch_setup_tag_protocol(), which is called from the equivalent
    spot in dsa_switch_teardown(). The positioning here also ensures that we
    won't have any use-after-free in tagging protocol (*rcv) ops, since the
    teardown sequence is as follows:
    
    dsa_tree_teardown
    -> dsa_tree_teardown_master
       -> dsa_master_teardown
          -> unsets master->dsa_ptr, making no further packets match the
             ETH_P_XDSA packet type handler
    -> dsa_tree_teardown_ports
       -> dsa_port_teardown
          -> dsa_slave_destroy
             -> unregisters DSA net devices, there is even a synchronize_net()
                in unregister_netdevice_many()
    -> dsa_tree_teardown_switches
       -> dsa_switch_teardown
          -> dsa_switch_teardown_tag_protocol
             -> finally frees the tagger-owned storage
    
    Fixes: 7f2973149c22 ("net: dsa: make tagging protocols connect to individual switches from a tree")
    Signed-off-by: Vladimir Oltean <vladimir.oltean@xxxxxxx>
    Reviewed-by: Saeed Mahameed <saeed@xxxxxxxxxx>
    Reviewed-by: Florian Fainelli <f.fainelli@xxxxxxxxx>
    Link: https://lore.kernel.org/r/20221114143551.1906361-1-vladimir.oltean@xxxxxxx
    Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/net/dsa/dsa2.c b/net/dsa/dsa2.c
index e537655e442b..befa954b0a47 100644
--- a/net/dsa/dsa2.c
+++ b/net/dsa/dsa2.c
@@ -850,6 +850,14 @@ static int dsa_switch_setup_tag_protocol(struct dsa_switch *ds)
 	return err;
 }
 
+static void dsa_switch_teardown_tag_protocol(struct dsa_switch *ds)
+{
+	const struct dsa_device_ops *tag_ops = ds->dst->tag_ops;
+
+	if (tag_ops->disconnect)
+		tag_ops->disconnect(ds);
+}
+
 static int dsa_switch_setup(struct dsa_switch *ds)
 {
 	struct dsa_devlink_priv *dl_priv;
@@ -953,6 +961,8 @@ static void dsa_switch_teardown(struct dsa_switch *ds)
 		ds->slave_mii_bus = NULL;
 	}
 
+	dsa_switch_teardown_tag_protocol(ds);
+
 	if (ds->ops->teardown)
 		ds->ops->teardown(ds);