Re: [PATCH v2 -next] usb/usbip: fix wrong data added to platform device

[Greg Kroah-Hartman]

On Sat, Oct 14, 2023 at 03:46:04PM +0800, Hongren Zheng wrote:
> .data of platform_device_info will be copied into .platform_data of
> struct device via platform_device_add_data.

That is crazy.

> However, vhcis[i] contains a spinlock, is dynamically allocated and
> used by other code, so it is not meant to be copied. The workaround
> was to use void *vhci as an agent, but it was removed in the commit
> suggested below.

Again, crazy, I'm amazed it works at all.

> This patch adds back the workaround and changes the way of using
> platform_data accordingly.
> 
> Reported-by: syzbot+e0dbc33630a092ccf033@xxxxxxxxxxxxxxxxxxxxxxxxx
> Closes: https://lore.kernel.org/r/00000000000029242706077f3145@xxxxxxxxxx/
> Reported-by: syzbot+6867a9777f4b8dc4e256@xxxxxxxxxxxxxxxxxxxxxxxxx
> Closes: https://lore.kernel.org/r/0000000000007634c1060793197c@xxxxxxxxxx/
> Fixes: b8aaf639b403 ("usbip: Use platform_device_register_full()")
> Tested-by: syzbot+6867a9777f4b8dc4e256@xxxxxxxxxxxxxxxxxxxxxxxxx
> Link: https://lore.kernel.org/r/0000000000007ac87d0607979b6b@xxxxxxxxxx/
> Signed-off-by: Hongren Zheng <i@xxxxxxxxxxx>
> ---
>  drivers/usb/usbip/vhci_hcd.c | 15 ++++++++-------
>  1 file changed, 8 insertions(+), 7 deletions(-)

I'll take this now, as it fixes a reported issue, but really, the root
problem should be fixed instead.  This is not how to treat platform data
at all.

thanks,

greg k-h