CVE-2026-23000 net/mlx5e: Fix crash on profile change rollback failure
In the Linux kernel, the following vulnerability has been resolved:

net/mlx5e: Fix crash on profile change rollback failure

mlx5e_netdev_change_profile can fail to attach a new profile and can
fail to rollback to old profile, in such case, we could end up with a
dangling netdev with a fully reset netdev_priv. A retry to change
profile, e.g. another attempt to call mlx5e_netdev_change_profile via
switchdev mode change, will crash trying to access the now NULL
priv->mdev.

This fix allows mlx5e_netdev_change_profile() to handle previous
failures and an empty priv, by not assuming priv is valid.

Pass netdev and mdev to all flows requiring
mlx5e_netdev_change_profile() and avoid passing priv.
In mlx5e_netdev_change_profile() check if current priv is valid, and if
not, just attach the new profile without trying to access the old one.

This fixes the following oops, when enabling switchdev mode for the 2nd
time after first time failure:

 ## Enabling switchdev mode first time:

mlx5_core 0012:03:00.1: E-Switch: Supported tc chains and prios offload
workqueue: Failed to create a rescuer kthread for wq "mlx5e": -EINTR
mlx5_core 0012:03:00.1: mlx5e_netdev_init_profile:6214:(pid 37199): mlx5e_priv_init failed, err=-12
mlx5_core 0012:03:00.1 gpu3rdma1: mlx5e_netdev_change_profile: new profile init failed, -12
workqueue: Failed to create a rescuer kthread for wq "mlx5e": -EINTR
mlx5_core 0012:03:00.1: mlx5e_netdev_init_profile:6214:(pid 37199): mlx5e_priv_init failed, err=-12
mlx5_core 0012:03:00.1 gpu3rdma1: mlx5e_netdev_change_profile: failed to rollback to orig profile, -12
                                                                         ^^^^^^^^
mlx5_core 0000:00:03.0: E-Switch: Disable: mode(LEGACY), nvfs(0), necvfs(0), active vports(0)

 ## retry: Enabling switchdev mode 2nd time:

mlx5_core 0000:00:03.0: E-Switch: Supported tc chains and prios offload
BUG: kernel NULL pointer dereference, address: 0000000000000038
 #PF: supervisor read access in kernel mode
 #PF: error_code(0x0000) - not-present page
PGD 0 P4D 0
Oops: Oops: 0000 [#1] SMP NOPTI
CPU: 13 UID: 0 PID: 520 Comm: devlink Not tainted 6.18.0-rc4+ #91 PREEMPT(voluntary)
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-2.fc40 04/01/2014
RIP: 0010:mlx5e_detach_netdev+0x3c/0x90
Code: 50 00 00 f0 80 4f 78 02 48 8b bf e8 07 00 00 48 85 ff 74 16 48 8b 73 78 48 d1 ee 83 e6 01 83 f6 01 40 0f b6 f6 e8 c4 42 00 00 <48> 8b 45 38 48 85 c0 74 08 48 89 df e8 cc 47 40 1e 48 8b bb f0 07
RSP: 0018:ffffc90000673890 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffff8881036a89c0 RCX: 0000000000000000
RDX: ffff888113f63800 RSI: ffffffff822fe720 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000002dcd R09: 0000000000000000
R10: ffffc900006738e8 R11: 00000000ffffffff R12: 0000000000000000
R13: 0000000000000000 R14: ffff8881036a89c0 R15: 0000000000000000
FS:  00007fdfb8384740(0000) GS:ffff88856a9d6000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000038 CR3: 0000000112ae0005 CR4: 0000000000370ef0
Call Trace:
 <TASK>
 mlx5e_netdev_change_profile+0x45/0xb0
 mlx5e_vport_rep_load+0x27b/0x2d0
 mlx5_esw_offloads_rep_load+0x72/0xf0
 esw_offloads_enable+0x5d0/0x970
 mlx5_eswitch_enable_locked+0x349/0x430
 ? is_mp_supported+0x57/0xb0
 mlx5_devlink_eswitch_mode_set+0x26b/0x430
 devlink_nl_eswitch_set_doit+0x6f/0xf0
 genl_family_rcv_msg_doit+0xe8/0x140
 genl_rcv_msg+0x18b/0x290
 ? __pfx_devlink_nl_pre_doit+0x10/0x10
 ? __pfx_devlink_nl_eswitch_set_doit+0x10/0x10
 ? __pfx_devlink_nl_post_doit+0x10/0x10
 ? __pfx_genl_rcv_msg+0x10/0x10
 netlink_rcv_skb+0x52/0x100
 genl_rcv+0x28/0x40
 netlink_unicast+0x282/0x3e0
 ? __alloc_skb+0xd6/0x190
 netlink_sendmsg+0x1f7/0x430
 __sys_sendto+0x213/0x220
 ? __sys_recvmsg+0x6a/0xd0
 __x64_sys_sendto+0x24/0x30
 do_syscall_64+0x50/0x1f0
 entry_SYSCALL_64_after_hwframe+0x76/0x7e
RIP: 0033:0x7fdfb8495047
CVSS v3.1 score: 5.5