xhci: tegra: Prevent error pointer dereference

Quoted 22 lines · Greg Kroah-Hartman

Quoted 21 lines · Thierry Reding

From: Thierry Reding <[email protected]>

During initialization, the host and super-speed power domains will contain an ERR_PTR() encoded error code rather than being NULL. To avoid a crash, use a !IS_ERR_OR_NULL() condition during cleanup.

Signed-off-by Thierry Reding <[email protected]>

---
 drivers/usb/host/xhci-tegra.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

drivers/usb/host/xhci-tegra.c +1 -1

index 938ff06c0349..efb0cad8710e 100644
@@ -941,9 +941,9 @@ static void tegra_xusb_powerdomain_remove(struct device *dev,
 		device_link_del(tegra->genpd_dl_ss);
 	if (tegra->genpd_dl_host)
 		device_link_del(tegra->genpd_dl_host);
-	if (tegra->genpd_dev_ss)
+	if (!IS_ERR_OR_NULL(tegra->genpd_dev_ss))

Quoted 8 lines

drivers/usb/host/xhci-tegra.c static void tegra_xusb_powerdomain_remove(struct device *dev, · line 948

Quoted 5 lines

drivers/usb/host/xhci-tegra.c +1 -1

 		dev_pm_domain_detach(tegra->genpd_dev_ss, true);
-	if (tegra->genpd_dev_host)
+	if (!IS_ERR_OR_NULL(tegra->genpd_dev_host))
 		dev_pm_domain_detach(tegra->genpd_dev_host, true);
 }

Should this go to older kernels? If so, any hint as to what commit this "fixes:"?

Technically this:

Fixes 6494a9ad86de ("usb: xhci: tegra: Add genpd support")

which was merged into v4.20.

However, I have never seen this actually crash on current kernels and only came across it while working on a change to reset controls which can cause dev_pm_domain_attach_by_name() to fail. That function can't fail in current kernels, so I don't think we need to fix this in old kernels. So if we can get this into v5.0, that'd be good enough for me.