Re: [PATCH v3 net] net: wwan: iosm: fix NULL pointer dereference when removing device

[Simon Horman <simon.horman@corigine.com>]

On Tue, May 16, 2023 at 09:09:46PM +0530, m.chetan.kumar@linux.intel.com wrote:
> From: M Chetan Kumar <m.chetan.kumar@linux.intel.com>
> 
> In suspend and resume cycle, the removal and rescan of device ends
> up in NULL pointer dereference.
> 
> During driver initialization, if the ipc_imem_wwan_channel_init()
> fails to get the valid device capabilities it returns an error and
> further no resource (wwan struct) will be allocated. Now in this
> situation if driver removal procedure is initiated it would result
> in NULL pointer exception since unallocated wwan struct is dereferenced
> inside ipc_wwan_deinit().
> 
> ipc_imem_run_state_worker() to handle the called functions return value
> and to release the resource in failure case. It also reports the link
> down event in failure cases. The user space application can handle this
> event to do a device reset for restoring the device communication.
> 
> Fixes: 3670970dd8c6 ("net: iosm: shared memory IPC interface")
> Reported-by: Samuel Wein PhD <sam@samwein.com>
> Closes: https://lore.kernel.org/netdev/20230427140819.1310f4bd@kernel.org/T/
> Signed-off-by: M Chetan Kumar <m.chetan.kumar@linux.intel.com>
> --
> v2 -> v3:
> * Fix review comments given by Simon Horman.
> - use second label for ipc_mux_deinit() since mux will be uninitalized in
> other failure cases.
> v1 -> v2:
> * Fix review comments given by Simon Horman.
> - goto labes renamed to reflect after usage instead where they are
> called from.
> - ipc_mux_deinit() checks for initalization state so is safe to keep
> under common err_out.

Reviewed-by: Simon Horman <simon.horman@corigine.com>