Re: [PATCH 1/4] usbip: add sysfs_lock to synchronize sysfs code paths

[Shuah Khan <skhan@linuxfoundation.org>]

On 4/16/21 2:53 PM, Tom Seewald wrote:
> From: Shuah Khan <skhan@linuxfoundation.org>
> 
> commit 4e9c93af7279b059faf5bb1897ee90512b258a12 upstream.
> 
> Fuzzing uncovered race condition between sysfs code paths in usbip
> drivers. Device connect/disconnect code paths initiated through
> sysfs interface are prone to races if disconnect happens during
> connect and vice versa.
> 
> This problem is common to all drivers while it can be reproduced easily
> in vhci_hcd. Add a sysfs_lock to usbip_device struct to protect the paths.
> 
> Use this in vhci_hcd to protect sysfs paths. For a complete fix, usip_host
> and usip-vudc drivers and the event handler will have to use this lock to
> protect the paths. These changes will be done in subsequent patches.
> 
> Cc: stable@vger.kernel.org # 4.9.x
> Reported-and-tested-by: syzbot+a93fba6d384346a761e3@syzkaller.appspotmail.com
> Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
> Link: https://lore.kernel.org/r/b6568f7beae702bbc236a545d3c020106ca75eac.1616807117.git.skhan@linuxfoundation.org
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Signed-off-by: Tom Seewald <tseewald@gmail.com>
> ---
>   drivers/usb/usbip/usbip_common.h |  3 +++
>   drivers/usb/usbip/vhci_hcd.c     |  1 +
>   drivers/usb/usbip/vhci_sysfs.c   | 30 +++++++++++++++++++++++++-----
>   3 files changed, 29 insertions(+), 5 deletions(-)
> 

Thank you for the backport.

Reviewed-by: Shuah Khan <skhan@linuxfoundation.org>

Greg, please pick this up for 4.9.x

thanks,
-- Shuah