CVE-2017-8064 (published 2017-04-23T05:59Z)

drivers/media/usb/dvb-usb-v2/dvb_usb_core.c in the Linux kernel 4.9.x and 4.10.x before 4.10.12 interacts incorrectly with the CONFIG_VMAP_STACK option, which allows local users to cause a denial of service (system crash or memory corruption) or possibly have unspecified other impact by leveraging use of more than one virtual page for a DMA scatterlist.

Severity: HIGH
CVSS v2 base score: 7.2 (AV:L/AC:L/Au:N/C:C/I:C/A:C)
CVSS v3 base score: 7.8, HIGH (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H)

Weakness information:
cwe_id: CWE-119
cwe_name: Improper Restriction of Operations within the Bounds of a Memory Buffer
description: The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.
extended_description: 
            Certain languages allow direct addressing of memory locations and do not automatically ensure that these locations are valid for the memory buffer that is being referenced. This can cause read or write operations to be performed on memory locations that may be associated with other variables, data structures, or internal program data.
         
         

Fix information:
repo_url: https://github.com/torvalds/linux
commit_details: repo_url: https://github.com/torvalds/linux
author: Arnd Bergmann
author_date: 2017-02-02 12:36:01-02:00
msg: [media] dvb-usb-v2: avoid use-after-free

I ran into a stack frame size warning because of the on-stack copy of
the USB device structure:

drivers/media/usb/dvb-usb-v2/dvb_usb_core.c: In function 'dvb_usbv2_disconnect':
drivers/media/usb/dvb-usb-v2/dvb_usb_core.c:1029:1: error: the frame size of 1104 bytes is larger than 1024 bytes [-Werror=frame-larger-than=]

Copying a device structure like this is wrong for a number of other reasons
too aside from the possible stack overflow. One of them is that the
dev_info() call will print the name of the device later, but AFAICT
we have only copied a pointer to the name earlier and the actual name
has been freed by the time it gets printed.

This removes the on-stack copy of the device and instead copies the
device name using kstrdup(). I'm ignoring the possible failure here
as both printk() and kfree() are able to deal with NULL pointers.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
repository: repo_url: https://github.com/torvalds/linux
repo_name: torvalds/linux
description: Linux kernel source tree
repo_language: C
owner: torvalds
file_changes: filename: dvb_usb_core.c
change_type: ModificationType.MODIFY
diff: @@ -1012,8 +1012,8 @@ EXPORT_SYMBOL(dvb_usbv2_probe);
 void dvb_usbv2_disconnect(struct usb_interface *intf)
 {
 	struct dvb_usb_device *d = usb_get_intfdata(intf);
-	const char *name = d->name;
-	struct device dev = d->udev->dev;
+	const char *devname = kstrdup(dev_name(&d->udev->dev), GFP_KERNEL);
+	const char *drvname = d->name;
 
 	dev_dbg(&d->udev->dev, "%s: bInterfaceNumber=%d\n", __func__,
 			intf->cur_altsetting->desc.bInterfaceNumber);
@@ -1023,8 +1023,9 @@ void dvb_usbv2_disconnect(struct usb_interface *intf)
 
 	dvb_usbv2_exit(d);
 
-	dev_info(&dev, "%s: '%s' successfully deinitialized and disconnected\n",
-			KBUILD_MODNAME, name);
+	pr_info("%s: '%s:%s' successfully deinitialized and disconnected\n",
+		KBUILD_MODNAME, drvname, devname);
+	kfree(devname);
 }
 EXPORT_SYMBOL(dvb_usbv2_disconnect);
 

programming_language: C