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[220.133.187.190]) by smtp.gmail.com with ESMTPSA id w5-v6sm16770209pfn.44.2018.09.17.00.05.54 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 17 Sep 2018 00:05:56 -0700 (PDT) Content-Type: text/plain; charset=us-ascii; delsp=yes; format=flowed Mime-Version: 1.0 (Mac OS X Mail 11.5 \(3445.9.1\)) Subject: Re: [PATCH] usb: core: safely deal with the dynamic quirk lists From: Kai-Heng Feng In-Reply-To: <20180914085816.10888-1-harry.pan@intel.com> Date: Mon, 17 Sep 2018 15:05:51 +0800 Cc: LKML , gs0622@gmail.com, jongpil19.jung@samsung.com, rajatja@chromium.org, Greg KH , Alan Stern , Felipe Balbi , snecknico@gmail.com, jackstocker.93@gmail.com, oneukum@suse.com, linux-usb@vger.kernel.org Content-Transfer-Encoding: 7bit Message-Id: <8950C3C8-AF9B-49DF-BE29-5F6892FCCEC8@canonical.com> References: <20180914085816.10888-1-harry.pan@intel.com> To: Harry Pan X-Mailer: Apple Mail (2.3445.9.1) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org at 16:58, Harry Pan wrote: > Applying dynamic usbcore quirks in early booting when the slab is > not yet ready would cause kernel panic of null pointer dereference > because the quirk_count has been counted as 1 while the quirk_list > was failed to allocate. > > i.e., > [ 1.044970] BUG: unable to handle kernel NULL pointer dereference > at (null) > [ 1.044995] IP: [] usb_detect_quirks+0x88/0xd1 > [ 1.045016] PGD 0 > [ 1.045026] Oops: 0000 [#1] PREEMPT SMP > [ 1.046986] gsmi: Log Shutdown Reason 0x03 > [ 1.046995] Modules linked in: > [ 1.047008] CPU: 0 PID: 81 Comm: kworker/0:3 Not tainted 4.4.154 #28 > [ 1.047016] Hardware name: Google Coral/Coral, BIOS > Google_Coral.10068.27.0 12/04/2017 > [ 1.047028] Workqueue: usb_hub_wq hub_event > [ 1.047037] task: ffff88017a321c80 task.stack: ffff88017a384000 > [ 1.047044] RIP: 0010:[] [] > usb_detect_quirks+0x88/0xd1 > > To tackle this odd, let's balance the quirk_count to 0 when the kcalloc > call fails, and defer the quirk setting into a lower level callback > which ensures that the kernel memory management has been initialized. > > Fixes: 027bd6cafd9a ("usb: core: Add "quirks" parameter for usbcore") > > Signed-off-by: Harry Pan Thanks for the catch! This issue doesn't appear when usbcore is built as module. Acked-by: Kai-Heng Feng > --- > drivers/usb/core/quirks.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/usb/core/quirks.c b/drivers/usb/core/quirks.c > index 097057d2eacf..1fe9843fb9c8 100644 > --- a/drivers/usb/core/quirks.c > +++ b/drivers/usb/core/quirks.c > @@ -58,6 +58,7 @@ static int quirks_param_set(const char *val, const > struct kernel_param *kp) > quirk_list = kcalloc(quirk_count, sizeof(struct quirk_entry), > GFP_KERNEL); > if (!quirk_list) { > + quirk_count = 0; > mutex_unlock(&quirk_mutex); > return -ENOMEM; > } > @@ -154,7 +155,7 @@ static struct kparam_string quirks_param_string = { > .string = quirks_param, > }; > > -module_param_cb(quirks, &quirks_param_ops, &quirks_param_string, 0644); > +device_param_cb(quirks, &quirks_param_ops, &quirks_param_string, 0644); > MODULE_PARM_DESC(quirks, "Add/modify USB quirks by specifying quirks=vendorID:productID:quirks"); > > /* Lists of quirky USB devices, split in device quirks and interface quirks. > -- > 2.16.4