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(80.71.142.18.ipv4.parknet.dk. [80.71.142.18]) by smtp.gmail.com with ESMTPSA id z24-20020a1c4c18000000b0037bd7f40771sm340380wmf.30.2022.02.21.12.35.42 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 21 Feb 2022 12:35:42 -0800 (PST) From: =?UTF-8?q?Alvin=20=C5=A0ipraga?= To: Andrew Lunn , Vivien Didelot , Florian Fainelli , Vladimir Oltean , "David S. Miller" , Jakub Kicinski , =?UTF-8?q?Alvin=20=C5=A0ipraga?= Cc: Vladimir Oltean , netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v2 net] net: dsa: fix panic when removing unoffloaded port from bridge Date: Mon, 21 Feb 2022 21:35:38 +0100 Message-Id: <20220221203539.310690-1-alvin@pqrs.dk> X-Mailer: git-send-email 2.35.1 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Alvin =C5=A0ipraga 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: d3eed0e57d5d ("net: dsa: keep the bridge_dev and bridge_num as part = of the same structure") Signed-off-by: Alvin =C5=A0ipraga Reviewed-by: Florian Fainelli Reviewed-by: Vladimir Oltean --- v1 -> v2: - replace trailing comma with semicolon *facepalm* --- 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 eef4a98f2628..1a40c52f5a42 100644 --- a/net/dsa/port.c +++ b/net/dsa/port.c @@ -395,10 +395,17 @@ void dsa_port_bridge_leave(struct dsa_port *dp, struc= t net_device *br) .tree_index =3D dp->ds->dst->index, .sw_index =3D dp->ds->index, .port =3D dp->index, - .bridge =3D *dp->bridge, }; int err; =20 + /* If the port could not be offloaded to begin with, then + * there is nothing to do. + */ + if (!dp->bridge) + return; + + info.bridge =3D *dp->bridge; + /* Here the port is already unbridged. Reflect the current configuration * so that drivers can program their chips accordingly. */ --=20 2.35.1