Messages in this thread | | | Date | Mon, 6 Dec 2021 16:29:53 -0800 | From | Matthias Kaehlcke <> | Subject | Re: [PATCH] usb: dwc3: dwc3-qcom: Avoid use-after-free when USB defers or unbinds |
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On Mon, Dec 06, 2021 at 03:28:47PM -0800, Douglas Anderson wrote: > On sc7180-trogdor class devices with 'fw_devlink=permissive' and KASAN > enabled, you'll see a Use-After-Free reported at bootup. > > The root of the problem is that dwc3_qcom_of_register_core() is adding > a devm-allocated "tx-fifo-resize" property to its device tree node > using of_add_property(). > > The issue is that of_add_property() makes a _permanent_ addition to > the device tree that lasts until reboot. That means allocating memory > for the property using "devm" managed memory is a terrible idea since > that memory will be freed upon probe deferral or device > unbinding. Let's change to just allocate memory once and never free > it. This sorta looks like a leak but isn't truly one, since only one > property will be allocated per device tree node per boot. > > NOTE: one would think that perhaps it would be better to use > of_remove_property() and then be able to free the property on device > remove. That sounds good until you read the comments for > of_remove_property(), which says that properties are never really > removed and they're just moved to the side. > > Fixes: cefdd52fa045 ("usb: dwc3: dwc3-qcom: Enable tx-fifo-resize property by default") > Signed-off-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Matthias Kaehlcke <mka@chromium.org>
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