net/mlx5: Handle pairing of E-switch via uplink un/load APIs
CVE: CVE-2023-53347
Component: kernel
CWE: CWE-476
Severity: Moderate
CVSS v3: 5.9/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:H
Release date: 2023-01-01T00:00:00+00:00

In the Linux kernel, the following vulnerability has been resolved:

net/mlx5: Handle pairing of E-switch via uplink un/load APIs

In case user switch a device from switchdev mode to legacy mode, mlx5
first unpair the E-switch and afterwards unload the uplink vport.
From the other hand, in case user remove or reload a device, mlx5
first unload the uplink vport and afterwards unpair the E-switch.

The latter is causing a bug[1], hence, handle pairing of E-switch as
part of uplink un/load APIs.

[1]
In case VF_LAG is used, every tc fdb flow is duplicated to the peer
esw. However, the original esw keeps a pointer to this duplicated
flow, not the peer esw.
e.g.: if user create tc fdb flow over esw0, the flow is duplicated
over esw1, in FW/HW, but in SW, esw0 keeps a pointer to the duplicated
flow.
During module unload while a peer tc fdb flow is still offloaded, in
case the first device to be removed is the peer device (esw1 in the
example above), the peer net-dev is destroyed, and so the mlx5e_priv
is memset to 0.
Afterwards, the peer device is trying to unpair himself from the
original device (esw0 in the example above). Unpair API invoke the
original device to clear peer flow from its eswitch (esw0), but the
peer flow, which is stored over the original eswitch (esw0), is
trying to use the peer mlx5e_priv, which is memset to 0 and result in
bellow kernel-oops.

[  157.964081 ] BUG: unable to handle page fault for address: 000000000002ce60
[  157.964662 ] #PF: supervisor read access in kernel mode
[  157.965123 ] #PF: error_code(0x0000) - not-present page
[  157.965582 ] PGD 0 P4D 0
[  157.965866 ] Oops: 0000 [#1] SMP
[  157.967670 ] RIP: 0010:mlx5e_tc_del_fdb_flow+0x48/0x460 [mlx5_core]
[  157.976164 ] Call Trace:
[  157.976437 ]  <TASK>
[  157.976690 ]  __mlx5e_tc_del_fdb_peer_flow+0xe6/0x100 [mlx5_core]
[  157.977230 ]  mlx5e_tc_clean_fdb_peer_flows+0x67/0x90 [mlx5_core]
[  157.977767 ]  mlx5_esw_offloads_unpair+0x2d/0x1e0 [mlx5_core]
[  157.984653 ]  mlx5_esw_offloads_devcom_event+0xbf/0x130 [mlx5_core]
[  157.985212 ]  mlx5_devcom_send_event+0xa3/0xb0 [mlx5_core]
[  157.985714 ]  esw_offloads_disable+0x5a/0x110 [mlx5_core]
[  157.986209 ]  mlx5_eswitch_disable_locked+0x152/0x170 [mlx5_core]
[  157.986757 ]  mlx5_eswitch_disable+0x51/0x80 [mlx5_core]
[  157.987248 ]  mlx5_unload+0x2a/0xb0 [mlx5_core]
[  157.987678 ]  mlx5_uninit_one+0x5f/0xd0 [mlx5_core]
[  157.988127 ]  remove_one+0x64/0xe0 [mlx5_core]
[  157.988549 ]  pci_device_remove+0x31/0xa0
[  157.988933 ]  device_release_driver_internal+0x18f/0x1f0
[  157.989402 ]  driver_detach+0x3f/0x80
[  157.989754 ]  bus_remove_driver+0x70/0xf0
[  157.990129 ]  pci_unregister_driver+0x34/0x90
[  157.990537 ]  mlx5_cleanup+0xc/0x1c [mlx5_core]
[  157.990972 ]  __x64_sys_delete_module+0x15a/0x250
[  157.991398 ]  ? exit_to_user_mode_prepare+0xea/0x110
[  157.991840 ]  do_syscall_64+0x3d/0x90
[  157.992198 ]  entry_SYSCALL_64_after_hwframe+0x46/0xb0


Remediation:
Mitigation for this issue is either not available or the currently available options don't meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.