Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Mon, 17 Apr 2023 12:25:21 +0300
From:   Dan Carpenter <error27@gmail.com>
To:     Dongliang Mu <dzm91@hust.edu.cn>, Vicki Pfau <vi@endrift.com>
Cc:     Dmitry Torokhov <dmitry.torokhov@gmail.com>,
        Pavel Rojtberg <rojtberg@gmail.com>,
        Nate Yocom <nate@yocom.org>,
        Mattijs Korpershoek <mkorpershoek@baylibre.com>,
        John Butler <radon86dev@gmail.com>,
        Matthias Benkmann <matthias.benkmann@gmail.com>,
        Christopher Crockett <chaorace@gmail.com>,
        Santosh De Massari <s.demassari@gmail.com>,
        hust-os-kernel-patches@googlegroups.com,
        syzbot+a3f758b8d8cb7e49afec@syzkaller.appspotmail.com,
        "Pierre-Loup A. Griffais" <pgriffais@valvesoftware.com>,
        linux-input@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] Input: xpad - fix GPF in xpad_probe
Message-ID: <c3e0823b-2b03-4dab-b7cb-a8bc5151f0b1@kili.mountain>
References: <20230414125603.686123-1-dzm91@hust.edu.cn>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20230414125603.686123-1-dzm91@hust.edu.cn>
Precedence: bulk

On Fri, Apr 14, 2023 at 08:55:47PM +0800, Dongliang Mu wrote:
> In xpad_probe(), it does not allocate xpad->dev with input_dev type.
> Then, when it invokes dev_warn with 1st argument - &xpad->dev->dev, it
> would trigger GPF.

What is a call tree for this?  Actually I found it from the bug report.
drivers/input/joystick/xpad.c
  2034                  if (error)
  2035                          dev_warn(&xpad->dev->dev,
  2036                                   "unable to receive magic message: %d\n",
  2037                                   error);
  2038          }

> 
> Fix this by allocating xpad->dev, its error handling and cleanup
> operations in the remove function.
> 
> Note that this crash does not have any reproducer, so the patch
> only passes compilation testing.

The xpad->dev = input_dev; already happens in xpad_init_input().  We
shouldn't allocate it twice.  I think the fix is to just use a different
device pointer for the dev_warn().  Why not use &xpad->intf->dev?

> 
> Reported-by: syzbot+a3f758b8d8cb7e49afec@syzkaller.appspotmail.com

Could you use a Link tag to link to the bug report?
Link: https://groups.google.com/g/syzkaller-bugs/c/iMhTgpGuIbM

This needs a Fixes tag.

Fixes: db7220c48d8d ("Input: xpad - fix support for some third-party controllers")

regards,
dan carpenter