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Sun, 13 Sep 2026 17:51:37 -0700 (PDT) Received: from google.com ([2a00:79e0:2ebe:8:a739:376c:7eb4:ea2d]) by smtp.gmail.com with ESMTPSA id a92af1059eb24-14365a598aasm20689137c88.1.2026.09.13.17.51.36 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 13 Sep 2026 17:51:37 -0700 (PDT) Date: Sun, 13 Sep 2026 17:51:34 -0700 From: Dmitry Torokhov To: Yogesh Gaur Cc: linux-input@vger.kernel.org, linux-kernel@vger.kernel.org, Christopher Heiny , Andrew Duggan , syzbot+09103639e39c989e3ed3@syzkaller.appspotmail.com Subject: Re: [PATCH] Input: synaptics-rmi4 - fix NULL dereference in the PM callbacks Message-ID: References: <20260908165925.2030-1-yogeshgaur.83@gmail.com> Precedence: bulk X-Mailing-List: linux-input@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260908165925.2030-1-yogeshgaur.83@gmail.com> Hi Yogesh, On Tue, Sep 08, 2026 at 10:29:25PM +0530, Yogesh Gaur wrote: > rmi_driver_suspend() and rmi_driver_resume() are exported for the > transport drivers; hid-rmi calls them straight from its ->suspend and > ->resume. Both reach code that dereferences the driver data right away: > > static int rmi_suspend_functions(struct rmi_device *rmi_dev) > { > struct rmi_driver_data *data = dev_get_drvdata(&rmi_dev->dev); > ... > list_for_each_entry(entry, &data->function_list, node) { > > That data is installed by rmi_driver_probe(), which binds only after the > transport driver has already published rmi_dev via > rmi_register_transport_device(). A runtime PM suspend of the underlying > USB interface in that window dereferences NULL: > > KASAN: null-ptr-deref in range [0x0000000000000078-0x000000000000007f] > RIP: 0010:dev_get_drvdata include/linux/device.h:989 [inline] > RIP: 0010:rmi_suspend_functions drivers/input/rmi4/rmi_driver.c:283 [inline] > RIP: 0010:rmi_driver_suspend+0x30/0x180 drivers/input/rmi4/rmi_driver.c:994 > Call Trace: > > rmi_suspend+0xa7/0xf0 drivers/hid/hid-rmi.c:448 > hid_suspend+0x4a3/0x530 drivers/hid/usbhid/hid-core.c:1618 > usb_suspend_interface drivers/usb/core/driver.c:1323 [inline] > usb_suspend_both+0x285/0x1040 drivers/usb/core/driver.c:1446 > usb_runtime_suspend+0x58/0x110 drivers/usb/core/driver.c:2000 > rpm_callback drivers/base/power/runtime.c:460 [inline] > rpm_suspend+0x8a0/0x17a0 drivers/base/power/runtime.c:698 > pm_runtime_work+0x132/0x1b0 drivers/base/power/runtime.c > > > rmi_disable_irq() and rmi_enable_irq(), reached a few lines further on, > look the driver data up the same way and then take > &data->enabled_mutex, so they would fault too. > > There is nothing to suspend or resume before the driver has bound, so > return success early while the driver data is not there yet. > > Fixes: 2b6a321da9a2 ("Input: synaptics-rmi4 - add support for Synaptics RMI4 devices") > Reported-by: syzbot+09103639e39c989e3ed3@syzkaller.appspotmail.com > Closes: https://syzkaller.appspot.com/bug?extid=09103639e39c989e3ed3 > Signed-off-by: Yogesh Gaur Thank you for the patch, but I already have a fix for this: https://patch.msgid.link/anQe8UiyUR4x0flD@google.com Thanks. -- Dmitry