From 2bfb953aeebf39d32f159450d69278b4c9c856dd Mon Sep 17 00:00:00 2001 From: Vladimir Oltean Date: Tue, 12 Jan 2021 02:48:31 +0200 Subject: net: dsa: clear devlink port type before unregistering slave netdevs [ Upstream commit 91158e1680b164c8d101144ca916a3dca10c3e17 ] Florian reported a use-after-free bug in devlink_nl_port_fill found with KASAN: (devlink_nl_port_fill) (devlink_port_notify) (devlink_port_unregister) (dsa_switch_teardown.part.3) (dsa_tree_teardown_switches) (dsa_unregister_switch) (bcm_sf2_sw_remove) (platform_remove) (device_release_driver_internal) (device_links_unbind_consumers) (device_release_driver_internal) (device_driver_detach) (unbind_store) Allocated by task 31: alloc_netdev_mqs+0x5c/0x50c dsa_slave_create+0x110/0x9c8 dsa_register_switch+0xdb0/0x13a4 b53_switch_register+0x47c/0x6dc bcm_sf2_sw_probe+0xaa4/0xc98 platform_probe+0x90/0xf4 really_probe+0x184/0x728 driver_probe_device+0xa4/0x278 __device_attach_driver+0xe8/0x148 bus_for_each_drv+0x108/0x158 Freed by task 249: free_netdev+0x170/0x194 dsa_slave_destroy+0xac/0xb0 dsa_port_teardown.part.2+0xa0/0xb4 dsa_tree_teardown_switches+0x50/0xc4 dsa_unregister_switch+0x124/0x250 bcm_sf2_sw_remove+0x98/0x13c platform_remove+0x44/0x5c device_release_driver_internal+0x150/0x254 device_links_unbind_consumers+0xf8/0x12c device_release_driver_internal+0x84/0x254 device_driver_detach+0x30/0x34 unbind_store+0x90/0x134 What happens is that devlink_port_unregister emits a netlink DEVLINK_CMD_PORT_DEL message which associates the devlink port that is getting unregistered with the ifindex of its corresponding net_device. Only trouble is, the net_device has already been unregistered. It looks like we can stub out the search for a corresponding net_device if we clear the devlink_port's type. This looks like a bit of a hack, but also seems to be the reason why the devlink_port_type_clear function exists in the first place. Fixes: 3122433eb533 ("net: dsa: Register devlink ports before calling DSA driver setup()") Signed-off-by: Vladimir Oltean Reviewed-by: Florian Fainelli Tested-by: Florian fainelli Reported-by: Florian Fainelli Link: https://lore.kernel.org/r/20210112004831.3778323-1-olteanv@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman --- net/dsa/dsa2.c | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'net/dsa') diff --git a/net/dsa/dsa2.c b/net/dsa/dsa2.c index 183003e45762..a47e0f9b20d0 100644 --- a/net/dsa/dsa2.c +++ b/net/dsa/dsa2.c @@ -353,9 +353,13 @@ static int dsa_port_devlink_setup(struct dsa_port *dp) static void dsa_port_teardown(struct dsa_port *dp) { + struct devlink_port *dlp = &dp->devlink_port; + if (!dp->setup) return; + devlink_port_type_clear(dlp); + switch (dp->type) { case DSA_PORT_TYPE_UNUSED: break; -- cgit v1.2.3