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([2402:f000:4:72:808::177e]) by smtp.gmail.com with ESMTPSA id b190sm42665669pga.37.2019.07.26.02.08.42 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 26 Jul 2019 02:08:45 -0700 (PDT) Subject: Re: [PATCH] input: touchscreen: wm97xx-core: Fix possible null-pointer dereferences in wm97xx_ts_input_open() To: Charles Keepax Cc: dmitry.torokhov@gmail.com, gregkh@linuxfoundation.org, tglx@linutronix.de, allison@lohutok.net, rdunlap@infradead.org, patches@opensource.cirrus.com, linux-input@vger.kernel.org, linux-kernel@vger.kernel.org References: <20190726084816.8487-1-baijiaju1990@gmail.com> <20190726090626.GA54126@ediswmail.ad.cirrus.com> From: Jia-Ju Bai Message-ID: <8abe9ecd-d6b4-1892-e496-edeeb62199c4@gmail.com> Date: Fri, 26 Jul 2019 17:08:44 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <20190726090626.GA54126@ediswmail.ad.cirrus.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2019/7/26 17:06, Charles Keepax wrote: > On Fri, Jul 26, 2019 at 04:48:16PM +0800, Jia-Ju Bai wrote: >> In wm97xx_ts_input_open(), there is an if statement on line 507 to check >> whether wm->mach_ops is NULL: >> if (wm->mach_ops && wm->mach_ops->acc_enabled) >> >> When wm->mach_ops is NULL, it is used on line 521: >> wm97xx_init_pen_irq(wm); >> BUG_ON(!wm->mach_ops->irq_enable); >> BUG_ON(!wm->mach_ops->irq_gpio); >> wm97xx_reg_write(..., reg & ~(wm->mach_ops->irq_gpio)) >> >> Thus, possible null-pointer dereferences may occur. >> >> To fix these bugs, wm->mach_ops is checked before calling >> wm97xx_init_pen_irq(). >> >> These bugs found by a static analysis tool STCheck written by us. >> >> Signed-off-by: Jia-Ju Bai >> --- >> drivers/input/touchscreen/wm97xx-core.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/drivers/input/touchscreen/wm97xx-core.c b/drivers/input/touchscreen/wm97xx-core.c >> index 0a174bd82915..f7bd0726a577 100644 >> --- a/drivers/input/touchscreen/wm97xx-core.c >> +++ b/drivers/input/touchscreen/wm97xx-core.c >> @@ -517,7 +517,7 @@ static int wm97xx_ts_input_open(struct input_dev *idev) >> wm->ts_reader_interval = wm->ts_reader_min_interval; >> >> wm->pen_is_down = 0; >> - if (wm->pen_irq) >> + if (wm->pen_irq && wm->mach_ops) >> wm97xx_init_pen_irq(wm); >> else >> dev_err(wm->dev, "No IRQ specified\n"); > This doesn't quite feel like the right fix as it would print an > error message saying "No IRQ specified", in the case the IRQ is > specified but the mach_ops have not been set. > > I would suggest either extending the existing BUG_ON or adding a > new check in wm97xx_init_pen_irq. Thanks for the advice. I will send a v2 patch of adding a new check in wm97xx_init_pen_irq(). Best wishes, Jia-Ju Bai