| Message ID | 20211207094327.1.Ie3cde3443039342e2963262a4c3ac36dc2c08b30@changeid (mailing list archive) |
|---|---|
| State | Not Applicable |
| Headers | show |
| Series | Revert "usb: dwc3: dwc3-qcom: Enable tx-fifo-resize property by default" | expand |
Quoting Douglas Anderson (2021-12-07 09:43:41) > This reverts commit cefdd52fa0455c0555c30927386ee466a108b060. > > 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 revert the patch since the system is still functional without > it. The fact that of_add_property() makes a permanent change is extra > fodder for those folks who were aruging that the device tree isn't > really the right way to pass information between parts of the > driver. It is an exercise left to the reader to submit a patch > re-adding the new feature in a way that makes everyone happier. > > Fixes: cefdd52fa045 ("usb: dwc3: dwc3-qcom: Enable tx-fifo-resize property by default") > Signed-off-by: Douglas Anderson <dianders@chromium.org> > --- Reviewed-by: Stephen Boyd <swboyd@chromium.org>
diff --git a/drivers/usb/dwc3/dwc3-qcom.c b/drivers/usb/dwc3/dwc3-qcom.c index 9abbd01028c5..3cb01cdd02c2 100644 --- a/drivers/usb/dwc3/dwc3-qcom.c +++ b/drivers/usb/dwc3/dwc3-qcom.c @@ -649,7 +649,6 @@ static int dwc3_qcom_of_register_core(struct platform_device *pdev) struct dwc3_qcom *qcom = platform_get_drvdata(pdev); struct device_node *np = pdev->dev.of_node, *dwc3_np; struct device *dev = &pdev->dev; - struct property *prop; int ret; dwc3_np = of_get_compatible_child(np, "snps,dwc3"); @@ -658,20 +657,6 @@ static int dwc3_qcom_of_register_core(struct platform_device *pdev) return -ENODEV; } - prop = devm_kzalloc(dev, sizeof(*prop), GFP_KERNEL); - if (!prop) { - ret = -ENOMEM; - dev_err(dev, "unable to allocate memory for property\n"); - goto node_put; - } - - prop->name = "tx-fifo-resize"; - ret = of_add_property(dwc3_np, prop); - if (ret) { - dev_err(dev, "unable to add property\n"); - goto node_put; - } - ret = of_platform_populate(np, NULL, NULL, dev); if (ret) { dev_err(dev, "failed to register dwc3 core - %d\n", ret);
This reverts commit cefdd52fa0455c0555c30927386ee466a108b060. 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 revert the patch since the system is still functional without it. The fact that of_add_property() makes a permanent change is extra fodder for those folks who were aruging that the device tree isn't really the right way to pass information between parts of the driver. It is an exercise left to the reader to submit a patch re-adding the new feature in a way that makes everyone happier. Fixes: cefdd52fa045 ("usb: dwc3: dwc3-qcom: Enable tx-fifo-resize property by default") Signed-off-by: Douglas Anderson <dianders@chromium.org> --- This is an alternative to the patch ("usb: dwc3: dwc3-qcom: Avoid use-after-free when USB defers or unbinds") [1]. During the review of my patch fixing the use-after-free it was proposed that it would be better to revert the broken patch and it would be up to folks who cared about it to re-submit it without the problems. [1] https://lore.kernel.org/r/20211206152844.1.I411110cc99c1dd66b01aa9aa25651acf8ff55da1@changeid drivers/usb/dwc3/dwc3-qcom.c | 15 --------------- 1 file changed, 15 deletions(-)