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USB: w1 ds2490: Fix bug caused by improper use of altsetting array

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commit c114944d7d 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 <stern@rowland.harvard.edu>
Reported-and-tested-by: syzbot+d65f673b847a1a96cdba@syzkaller.appspotmail.com
CC: <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Alan Stern
2019-04-22 11:16:04 -04:00
committed by Greg Kroah-Hartman
parent 5696fa3f42
commit 0bb71c26b3
1 changed files with 3 additions and 3 deletions
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6
drivers/w1/masters/ds2490.c
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@@ -1018,15 +1018,15 @@ static int ds_probe(struct usb_interface *intf,
/* 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) {
pr_info("Num endpoints=%d. It is not DS9490R.\n",
iface_desc->desc.bNumEndpoints);