Re: [PATCH] usb: gadget: u_ether: Fix NULL pointer deref in eth_get_drvinfo

[David Heidelberg]

On 16/03/2026 08:49, Kuen-Han Tsai wrote:
> Commit ec35c1969650 ("usb: gadget: f_ncm: Fix net_device lifecycle with
> device_move") reparents the gadget device to /sys/devices/virtual during
> unbind, clearing the gadget pointer. If the userspace tool queries on
> the surviving interface during this detached window, this leads to a
> NULL pointer dereference.
>
> Unable to handle kernel NULL pointer dereference
> Call trace:
>   eth_get_drvinfo+0x50/0x90
>   ethtool_get_drvinfo+0x5c/0x1f0
>   __dev_ethtool+0xaec/0x1fe0
>   dev_ethtool+0x134/0x2e0
>   dev_ioctl+0x338/0x560
>
> Add a NULL check for dev->gadget in eth_get_drvinfo(). When detached,
> skip copying the fw_version and bus_info strings, which is natively
> handled by ethtool_get_drvinfo for empty strings.
>
> Suggested-by: Val Packett <val@xxxxxxxxxxxx>
> Reported-by: Val Packett <val@xxxxxxxxxxxx>
> Closes: https://lore.kernel.org/linux-usb/10890524-cf83-4a71-b879-93e2b2cc1fcc@xxxxxxxxxxxx/
> Fixes: ec35c1969650 ("usb: gadget: f_ncm: Fix net_device lifecycle with device_move")
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Kuen-Han Tsai <khtsai@xxxxxxxxxx>
> ---

Works for us in sdm845-next too,

Tested-by: David Heidelberg <david@xxxxxxx>
--
David Heidelberg