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HID: usbhid: fix use-after-free bug 

This patch (as1592) fixes an obscure problem in the usbhid driver.
Under some circumstances, a control or interrupt-OUT URB can be
submitted twice.  This will happen if the first submission fails; the
queue pointers aren't updated, so the next time the queue is restarted
the same URB will be submitted again.

The problem is that raw_report gets deallocated during the first
submission.  The second submission will then dereference and try to
free an already-freed region of memory.  The patch fixes the problem
by setting raw_report to NULL when it is deallocated and checking for
NULL before dereferencing it.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
CC: Oliver Neukum <oliver@neukum.org>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
This commit is contained in:
Alan Stern 2012-07-19 16:08:21 -04:00 committed by Jiri Kosina
parent 61c901c569
commit 668160e5a8
1 changed files with 11 additions and 5 deletions
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16
drivers/hid/usbhid/hid-core.c
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@ -331,9 +331,12 @@ static int hid_submit_out(struct hid_device *hid)
usbhid->urbout->transfer_buffer_length = ((report->size - 1) >> 3) +
1 + (report->id > 0);
usbhid->urbout->dev = hid_to_usb_dev(hid);
memcpy(usbhid->outbuf, raw_report,
usbhid->urbout->transfer_buffer_length);
kfree(raw_report);
if (raw_report) {
memcpy(usbhid->outbuf, raw_report,
usbhid->urbout->transfer_buffer_length);
kfree(raw_report);
usbhid->out[usbhid->outtail].raw_report = NULL;
}
dbg_hid("submitting out urb\n");
@ -362,8 +365,11 @@ static int hid_submit_ctrl(struct hid_device *hid)
if (dir == USB_DIR_OUT) {
usbhid->urbctrl->pipe = usb_sndctrlpipe(hid_to_usb_dev(hid), 0);
usbhid->urbctrl->transfer_buffer_length = len;
memcpy(usbhid->ctrlbuf, raw_report, len);
kfree(raw_report);
if (raw_report) {
memcpy(usbhid->ctrlbuf, raw_report, len);
kfree(raw_report);
usbhid->ctrl[usbhid->ctrltail].raw_report = NULL;
}
} else {
int maxpacket, padlen;