From 3107c6c94abb6fcd7f79ac11050e33173a42f6c1 Mon Sep 17 00:00:00 2001 From: =?utf8?q?Alvin=20=C5=A0ipraga?= Date: Mon, 21 Feb 2022 21:35:38 +0100 Subject: [PATCH] net: dsa: fix panic when removing unoffloaded port from bridge MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit If a bridged port is not offloaded to the hardware - either because the underlying driver does not implement the port_bridge_{join,leave} ops, or because the operation failed - then its dp->bridge pointer will be NULL when dsa_port_bridge_leave() is called. Avoid dereferncing NULL. This fixes the following splat when removing a port from a bridge: Unable to handle kernel access to user memory outside uaccess routines at virtual address 0000000000000000 Internal error: Oops: 96000004 [#1] PREEMPT_RT SMP CPU: 3 PID: 1119 Comm: brctl Tainted: G O 5.17.0-rc4-rt4 #1 Call trace: dsa_port_bridge_leave+0x8c/0x1e4 dsa_slave_changeupper+0x40/0x170 dsa_slave_netdevice_event+0x494/0x4d4 notifier_call_chain+0x80/0xe0 raw_notifier_call_chain+0x1c/0x24 call_netdevice_notifiers_info+0x5c/0xac __netdev_upper_dev_unlink+0xa4/0x200 netdev_upper_dev_unlink+0x38/0x60 del_nbp+0x1b0/0x300 br_del_if+0x38/0x114 add_del_if+0x60/0xa0 br_ioctl_stub+0x128/0x2dc br_ioctl_call+0x68/0xb0 dev_ifsioc+0x390/0x554 dev_ioctl+0x128/0x400 sock_do_ioctl+0xb4/0xf4 sock_ioctl+0x12c/0x4e0 __arm64_sys_ioctl+0xa8/0xf0 invoke_syscall+0x4c/0x110 el0_svc_common.constprop.0+0x48/0xf0 do_el0_svc+0x28/0x84 el0_svc+0x1c/0x50 el0t_64_sync_handler+0xa8/0xb0 el0t_64_sync+0x17c/0x180 Code: f9402f00 f0002261 f9401302 913cc021 (a9401404) ---[ end trace 0000000000000000 ]--- Fixes: 4a1b05b7d272 ("net: dsa: keep the bridge_dev and bridge_num as part of the same structure") Signed-off-by: Alvin Å ipraga Reviewed-by: Vladimir Oltean Reviewed-by: Florian Fainelli Link: https://lore.kernel.org/r/20220221203539.310690-1-alvin@pqrs.dk Signed-off-by: Jakub Kicinski --- net/dsa/port.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/net/dsa/port.c b/net/dsa/port.c index eef4a98f26282..1a40c52f5a42d 100644 --- a/net/dsa/port.c +++ b/net/dsa/port.c @@ -395,10 +395,17 @@ void dsa_port_bridge_leave(struct dsa_port *dp, struct net_device *br) .tree_index = dp->ds->dst->index, .sw_index = dp->ds->index, .port = dp->index, - .bridge = *dp->bridge, }; int err; + /* If the port could not be offloaded to begin with, then + * there is nothing to do. + */ + if (!dp->bridge) + return; + + info.bridge = *dp->bridge; + /* Here the port is already unbridged. Reflect the current configuration * so that drivers can program their chips accordingly. */ -- 2.39.5