From 7fd078337201cf7468f53c3d9ef81ff78cb6df3b Mon Sep 17 00:00:00 2001 From: =?utf8?q?Bj=C3=B8rn=20Mork?= Date: Mon, 6 Nov 2017 15:32:18 +0100 Subject: [PATCH] net: qmi_wwan: fix divide by 0 on bad descriptors MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit A CDC Ethernet functional descriptor with wMaxSegmentSize = 0 will cause a divide error in usbnet_probe: divide error: 0000 [#1] PREEMPT SMP KASAN Modules linked in: CPU: 0 PID: 24 Comm: kworker/0:1 Not tainted 4.14.0-rc8-44453-g1fdc1a82c34f #56 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 Workqueue: usb_hub_wq hub_event task: ffff88006bef5c00 task.stack: ffff88006bf60000 RIP: 0010:usbnet_update_max_qlen+0x24d/0x390 drivers/net/usb/usbnet.c:355 RSP: 0018:ffff88006bf67508 EFLAGS: 00010246 RAX: 00000000000163c8 RBX: ffff8800621fce40 RCX: ffff8800621fcf34 RDX: 0000000000000000 RSI: ffffffff837ecb7a RDI: ffff8800621fcf34 RBP: ffff88006bf67520 R08: ffff88006bef5c00 R09: ffffed000c43f881 R10: ffffed000c43f880 R11: ffff8800621fc406 R12: 0000000000000003 R13: ffffffff85c71de0 R14: 0000000000000000 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff88006ca00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007ffe9c0d6dac CR3: 00000000614f4000 CR4: 00000000000006f0 Call Trace: usbnet_probe+0x18b5/0x2790 drivers/net/usb/usbnet.c:1783 qmi_wwan_probe+0x133/0x220 drivers/net/usb/qmi_wwan.c:1338 usb_probe_interface+0x324/0x940 drivers/usb/core/driver.c:361 really_probe drivers/base/dd.c:413 driver_probe_device+0x522/0x740 drivers/base/dd.c:557 Fix by simply ignoring the bogus descriptor, as it is optional for QMI devices anyway. Fixes: 423ce8caab7e ("net: usb: qmi_wwan: New driver for Huawei QMI based WWAN devices") Reported-by: Andrey Konovalov Signed-off-by: Bjørn Mork Signed-off-by: David S. Miller --- drivers/net/usb/qmi_wwan.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/net/usb/qmi_wwan.c b/drivers/net/usb/qmi_wwan.c index 8c3733608271..a4f229edcceb 100644 --- a/drivers/net/usb/qmi_wwan.c +++ b/drivers/net/usb/qmi_wwan.c @@ -681,7 +681,7 @@ static int qmi_wwan_bind(struct usbnet *dev, struct usb_interface *intf) } /* errors aren't fatal - we can live with the dynamic address */ - if (cdc_ether) { + if (cdc_ether && cdc_ether->wMaxSegmentSize) { dev->hard_mtu = le16_to_cpu(cdc_ether->wMaxSegmentSize); usbnet_get_ethernet_addr(dev, cdc_ether->iMACAddress); } -- 2.20.1