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Subject[PATCH 3.16 108/157] USB: w1 ds2490: Fix bug caused by improper use of altsetting array
3.16.72-rc1 review patch.  If anyone has any objections, please let me know.


From: Alan Stern <>

commit c114944d7d67f24e71562fcfc18d550ab787e4d4 upstream.

The syzkaller USB fuzzer spotted a slab-out-of-bounds bug in the
ds2490 driver. This bug is caused by improper use of the altsetting
array in the usb_interface structure (the array's entries are not
always stored in numerical order), combined with a naive assumption
that all interfaces probed by the driver will have the expected number
of altsettings.

The bug can be fixed by replacing references to the possibly
non-existent intf->altsetting[alt] entry with the guaranteed-to-exist
intf->cur_altsetting entry.

Signed-off-by: Alan Stern <>
Signed-off-by: Greg Kroah-Hartman <>
Signed-off-by: Ben Hutchings <>
drivers/w1/masters/ds2490.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

--- a/drivers/w1/masters/ds2490.c
+++ b/drivers/w1/masters/ds2490.c
@@ -1041,15 +1041,15 @@ static int ds_probe(struct usb_interface
/* alternative 3, 1ms interrupt (greatly speeds search), 64 byte bulk */
alt = 3;
err = usb_set_interface(dev->udev,
- intf->altsetting[alt].desc.bInterfaceNumber, alt);
+ intf->cur_altsetting->desc.bInterfaceNumber, alt);
if (err) {
dev_err(&dev->udev->dev, "Failed to set alternative setting %d "
"for %d interface: err=%d.\n", alt,
- intf->altsetting[alt].desc.bInterfaceNumber, err);
+ intf->cur_altsetting->desc.bInterfaceNumber, err);
goto err_out_clear;

- iface_desc = &intf->altsetting[alt];
+ iface_desc = intf->cur_altsetting;
if (iface_desc->desc.bNumEndpoints != NUM_EP-1) {
printk(KERN_INFO "Num endpoints=%d. It is not DS9490R.\n", iface_desc->desc.bNumEndpoints);
err = -EINVAL;
 \ /
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