Subject: Re: [PATCH iwl-net] idpf: fix adapter NULL pointer dereference on reboot

From: Simon Horman <[email-masked]>
Date: Mon, 10 Mar 2025 07:22:29 +0100

On Thu, Mar 06, 2025 at 04:39:56PM -0800, Emil Tantilov wrote:
> Driver calls idpf_remove() from idpf_shutdown(), which can end up
> calling idpf_remove() again when disabling SRIOV.
> 
> echo 1 > /sys/class/net/<netif>/device/sriov_numvfs
> reboot
> 
> BUG: kernel NULL pointer dereference, address: 0000000000000020
> ...
> RIP: 0010:idpf_remove+0x22/0x1f0 [idpf]
> ...
> ? idpf_remove+0x22/0x1f0 [idpf]
> ? idpf_remove+0x1e4/0x1f0 [idpf]
> pci_device_remove+0x3f/0xb0
> device_release_driver_internal+0x19f/0x200
> pci_stop_bus_device+0x6d/0x90
> pci_stop_and_remove_bus_device+0x12/0x20
> pci_iov_remove_virtfn+0xbe/0x120
> sriov_disable+0x34/0xe0
> idpf_sriov_configure+0x58/0x140 [idpf]
> idpf_remove+0x1b9/0x1f0 [idpf]
> idpf_shutdown+0x12/0x30 [idpf]
> pci_device_shutdown+0x35/0x60
> device_shutdown+0x156/0x200
> ...
> 
> Replace the direct idpf_remove() call in idpf_shutdown() with
> idpf_vc_core_deinit() and idpf_deinit_dflt_mbx(), which perform
> the bulk of the cleanup, such as stopping the init task, freeing IRQs,
> destroying the vports and freeing the mailbox.

Hi Emil,

I think it would be worth adding some commentary on the rest of
the clean-up performed by idpf_remove() and why it is correct
to no longer do so directly from a call to idpf_remove() from
idpf_shutdown() (IOW, it isn't clear to me :).

...