Messages in this thread | | | Date | Tue, 7 Dec 2010 15:47:13 +0100 (CET) | From | Jiri Kosina <> | Subject | Re: [PATCH 1/2] USB: HID: Fix race between disconnect and hiddev_ioctl |
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On Mon, 6 Dec 2010, Valentine Barshak wrote:
> A USB HID device can be disconnected at any time. > If this happens right before or while hiddev_ioctl is in progress, > the hiddev_ioctl tries to access invalid hiddev->hid pointer. > When the hid device is disconnected, the hiddev_disconnect() > ends up with a call to hid_device_release() which frees > hid_device, but doesn't set the hiddev->hid pointer to NULL. > If the deallocated memory region has been re-used by the kernel, > this can cause a crash or memory corruption. > > Since disconnect can happen at any time, we can't initialize > struct hid_device *hid = hiddev->hid at the beginning of ioctl > and then use it. > > This change checks hiddev->exist flag while holding > the existancelock and uses hid_device only if it exists.
The code duplication isn't really particularly nice, but I don't see any way around it that wouldn't complicate things even more.
I will be applying the patches, thanks.
(BTW your patches didn't reach mail mailbox, I had to dig them out from mailinglist -- did you receive bounces by any chance?).
Thanks,
-- Jiri Kosina SUSE Labs, Novell Inc.
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