> The whole kernel is full of situations where an int is returned and if it's > negative it's an error. Why is this location so different? > > Just check < 0 and be done with it. OK, whatever you prefer. I've attached the updated patch. (Greg, please add your Signed-off-by). Best, Mathias
commit 78e4a03cd3ae7c8f5957a170bc054fd89d7600f1
Author: Mathias Payer <mathias.payer@xxxxxxxxxxxxx>
Date: Sun Dec 9 16:45:09 2018 +0100
NET: hso: Fix OOB memory access in hso_probe/hso_get_config_data in hso.c
From: Hui Peng <benquike@xxxxxxxxx>
The function hso_probe reads if_num from the USB device (as an u8) and uses
it without a length check to index an array, resulting in an OOB memory read
in hso_probe or hso_get_config_data. Added a length check for both locations
and updated hso_probe to bail on error.
This issue has been assigned CVE-2018-19985.
Reported-by: Hui Peng <benquike@xxxxxxxxx>
Reported-by: Mathias Payer <mathias.payer@xxxxxxxxxxxxx>
Signed-off-by: Hui Peng <benquike@xxxxxxxxx>
Signed-off-by: Mathias Payer <mathias.payer@xxxxxxxxxxxxx>
diff --git a/drivers/net/usb/hso.c b/drivers/net/usb/hso.c
index 184c24baca15..d6916f787fce 100644
--- a/drivers/net/usb/hso.c
+++ b/drivers/net/usb/hso.c
@@ -2807,6 +2807,12 @@ static int hso_get_config_data(struct usb_interface *interface)
return -EIO;
}
+ /* check if we have a valid interface */
+ if (if_num > 16) {
+ kfree(config_data);
+ return -EINVAL;
+ }
+
switch (config_data[if_num]) {
case 0x0:
result = 0;
@@ -2877,10 +2883,18 @@ static int hso_probe(struct usb_interface *interface,
/* Get the interface/port specification from either driver_info or from
* the device itself */
- if (id->driver_info)
+ if (id->driver_info) {
+ /* if_num is controlled by the device, driver_info is a 0 terminated
+ * array. Make sure, the access is in bounds! */
+ for (i = 0; i <= if_num; ++i)
+ if (((u32 *)(id->driver_info))[i] == 0)
+ goto exit;
port_spec = ((u32 *)(id->driver_info))[if_num];
- else
+ } else {
port_spec = hso_get_config_data(interface);
+ if (port_spec < 0)
+ goto exit;
+ }
/* Check if we need to switch to alt interfaces prior to port
* configuration */
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