openvswitch gentling validation warning: missing .resv_start_op

[William Tu]

Intro:
======
When hit a kernel warning when loading openvswitch kernel module. Digging into the source code, we found it's due to the code snippet
        if (WARN_ON(i.cmd >= family->resv_start_op &&
                   (i.doit.validate || i.dumpit.validate)))
                 return -EINVAL;

in the gene_validate_ops() in net/netlink/genetlink.c, introduced in
108880a07bab genetlink: add iterator for walking family ops
from buglink about DPLL/SynCE
https://bugs.launchpad.net/bugs/2053155

How to fix:
===========
We need to cherry-pick the missing patch
Fixes: e4ba4554209f ("net: openvswitch: add missing .resv_start_op")

Author: Jakub Kicinski <email address hidden>
Date: Thu Oct 27 20:25:01 2022 -0700

    net: openvswitch: add missing .resv_start_op

    I missed one of the families in OvS when annotating .resv_start_op.
    This triggers the warning added in commit ce48ebdd5651 ("genetlink:
    limit the use of validation workarounds to old ops").

    Reported-by: <email address hidden>
    Fixes: 9c5d03d36251 ("genetlink: start to validate reserved header bytes")
    Link: https://<email address hidden>
    Signed-off-by: Jakub Kicinski <email address hidden>

Thanks!

How to reproduce:
=================
simply load the openvswitch.ko and dmesg

[ 1083.518212] WARNING: CPU: 2 PID: 17269 at net/netlink/genetlink.c:554 genl_validate_ops+0x134/0x254
...
[ 1083.518306] CPU: 2 PID: 17269 Comm: modprobe Tainted: G W OE 5.15.0-1037.39.10.g319565b-bluefield #g319565b
[ 1083.518309] Hardware name: https://www.mellanox.com BlueField SoC/BlueField SoC, BIOS 4.7.0.13056 Feb 28 2024
[ 1083.518311] pstate: 00400009 (nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
[ 1083.518313] pc : genl_validate_ops+0x134/0x254
[ 1083.518315] lr : genl_validate_ops+0x68/0x254
[ 1083.518317] sp : ffff80000a773810
[ 1083.518318] x29: ffff80000a773810 x28: ffff80000a773ba0 x27: ffffb1ea36f87318
[ 1083.518321] x26: ffffb1ea36f8cd20 x25: 0000000000000001 x24: ffffb1ea36f8cda8
[ 1083.518323] x23: 0000000000000000 x22: 0000000000000001 x21: ffffb1ea36f87210
[ 1083.518325] x20: ffffb1ea36f8b410 x19: 0000000000000001 x18: 0000000000000000
[ 1083.518328] x17: 0000000d00020008 x16: ffffb1ea4b70c2d0 x15: 0000003c00010006
[ 1083.518330] x14: 0000000068746170 x13: 0000000000000000 x12: 0000000000000001
[ 1083.518332] x11: 0000000000000000 x10: 0000000000000000 x9 : ffffb1ea4b709a5c
[ 1083.518335] x8 : 0000000000000000 x7 : 0000000000000000 x6 : ffffb1ea4d4218c0
[ 1083.518337] x5 : 0000000000000004 x4 : 0000000000000000 x3 : 0000000000000001
[ 1083.518339] x2 : 0000000000000000 x1 : 0000000000000000 x0 : 0000000000000003
[ 1083.518341] Call trace:
[ 1083.518343] genl_validate_ops+0x134/0x254
[ 1083.518344] genl_register_family+0x30/0x1f4
[ 1083.518347] dp_init+0xd4/0x174 [openvswitch]
[ 1083.518360] do_one_initcall+0x4c/0x250
[ 1083.518364] do_init_module+0x50/0x260
[ 1083.518368] load_module+0x9fc/0xbe0
[ 1083.518370] __do_sys_finit_module+0xa8/0x114
[ 1083.518372] __arm64_sys_finit_module+0x28/0x3c
[ 1083.518375] invoke_syscall+0x78/0x100
[ 1083.518379] el0_svc_common.constprop.0+0x54/0x184
[ 1083.518381] do_el0_svc+0x30/0xac
[ 1083.518383] el0_svc+0x48/0x160
[ 1083.518387] el0t_64_sync_handler+0xa4/0x12c
[ 1083.518390] el0t_64_sync+0x1a4/0x1a8
[ 1083.518392] ---[ end trace ec4279298c2ae7be ]---
[ 1083.830668] openvswitch: Open vSwitch switching datapath

[Ubuntu Kernel Bot (ubuntu-kernel-bot)]

This bug is awaiting verification that the linux-bluefield/5.15.0-1039.41 kernel in -proposed solves the problem. Please test the kernel and update this bug with the results. If the problem is solved, change the tag 'verification-needed-jammy-linux-bluefield' to 'verification-done-jammy-linux-bluefield'. If the problem still exists, change the tag 'verification-needed-jammy-linux-bluefield' to 'verification-failed-jammy-linux-bluefield'.

If verification is not done by 5 working days from today, this fix will be dropped from the source code, and this bug will be closed.

See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Thank you!