Re: [PATCH v2] usb: cdns3: Fix PCI device reference leak in cdns3_pci_probe()

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [High] usb: cdns3: UAF in cdns3_pci_probe() error path freeing shared drvdata
--

commit 4c0bd2a76b0d6740fa24b374ecb3e7b1b96c27ce
Author: Ma Ke <make_ruc2021@163.com>

usb: cdns3: Fix PCI device reference leak in cdns3_pci_probe()

This commit addresses a PCI device reference leak in the cdns3 driver by
ensuring pci_dev_put() is called on the device returned by
cdns3_get_second_fun(). It updates the probe and remove functions to
properly release the reference, including in error paths. A missing NULL
check before pci_is_enabled() in the remove function is also added.

> diff --git a/drivers/usb/cdns3/cdns3-pci-wrap.c b/drivers/usb/cdns3/cdns3-pci-wrap.c
> index fd06a3d8e638f..7799349bba771 100644
> --- a/drivers/usb/cdns3/cdns3-pci-wrap.c
> +++ b/drivers/usb/cdns3/cdns3-pci-wrap.c
[ ... ]
> @@ -165,11 +168,13 @@ static int cdns3_pci_probe(struct pci_dev *pdev,
>  		if (IS_ERR(wrap->plat_dev)) {
>  			err = PTR_ERR(wrap->plat_dev);
>  			kfree(wrap);
> -			return err;
> +			goto put_pci;
>  		}
>  	}

[Severity: High]
Can this error path free a shared drvdata object?

When pci_is_enabled(func) is true, wrap is retrieved from the sibling
function's drvdata:

cdns3_pci_probe() {
    ...
    if (pci_is_enabled(func)) {
        wrap = pci_get_drvdata(func);
    ...
}

If platform_device_register_full() fails later in the probe function, the
error path unconditionally calls kfree(wrap).

Because the sibling function still holds a pointer to this wrap object in
its drvdata, freeing it here can cause a use-after-free and potential
double-free when the sibling function is subsequently removed or accessed
(for example, when cdns3_pci_remove() dereferences wrap->devfn).

Should kfree(wrap) be skipped here if wrap was retrieved from the sibling
function rather than allocated in this probe call?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261012070310.3704130-1-make_ruc2021@163.com?part=1