[PATCH 6.6 038/254] phy: qcom-qusb2: Fix NULL pointer dereference on early suspend

Greg Kroah-Hartman
2026-01-28T15:30:15Z

From: Loic Poulain <loic.poulain@oss.qualcomm.com>

[ Upstream commit 1ca52c0983c34fca506921791202ed5bdafd5306 ]

Enabling runtime PM before attaching the QPHY instance as driver data
can lead to a NULL pointer dereference in runtime PM callbacks that
expect valid driver data. There is a small window where the suspend
callback may run after PM runtime enabling and before runtime forbid.
This causes a sporadic crash during boot:

```
Unable to handle kernel NULL pointer dereference at virtual address 00000000000000a1
[...]
CPU: 0 UID: 0 PID: 11 Comm: kworker/0:1 Not tainted 6.16.7+ #116 PREEMPT
Workqueue: pm pm_runtime_work
pstate: 20000005 (nzCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : qusb2_phy_runtime_suspend+0x14/0x1e0 [phy_qcom_qusb2]
lr : pm_generic_runtime_suspend+0x2c/0x44
[...]
```

Attach the QPHY instance as driver data before enabling runtime PM to
prevent NULL pointer dereference in runtime PM callbacks.

Reorder pm_runtime_enable() and pm_runtime_forbid() to prevent a
short window where an unnecessary runtime suspend can occur.

Use the devres-managed version to ensure PM runtime is symmetrically
disabled during driver removal for proper cleanup.

Fixes: 891a96f65ac3 ("phy: qcom-qusb2: Add support for runtime PM")
Signed-off-by: Loic Poulain <loic.poulain@oss.qualcomm.com>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Reviewed-by: Abel Vesa <abel.vesa@oss.qualcomm.com>
Link: https://patch.msgid.link/20251219085640.114473-1-loic.poulain@oss.qualcomm.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/phy/qualcomm/phy-qcom-qusb2.c | 16 ++++++++--------
1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/drivers/phy/qualcomm/phy-qcom-qusb2.c b/drivers/phy/qualcomm/phy-qcom-qusb2.c
index 531c3860c3160..d3c26a39873f7 100644
--- a/drivers/phy/qualcomm/phy-qcom-qusb2.c
+++ b/drivers/phy/qualcomm/phy-qcom-qusb2.c
@@ -1063,29 +1063,29 @@ static int qusb2_phy_probe(struct platform_device *pdev)
or->hsdisc_trim.override = true;
}

- pm_runtime_set_active(dev);
- pm_runtime_enable(dev);
+ dev_set_drvdata(dev, qphy);
+
/*
- * Prevent runtime pm from being ON by default. Users can enable
- * it using power/control in sysfs.
+ * Enable runtime PM support, but forbid it by default.
+ * Users can allow it again via the power/control attribute in sysfs.
*/
+ pm_runtime_set_active(dev);
pm_runtime_forbid(dev);
+ ret = devm_pm_runtime_enable(dev);
+ if (ret)
+ return ret;

generic_phy = devm_phy_create(dev, NULL, &qusb2_phy_gen_ops);
if (IS_ERR(generic_phy)) {
ret = PTR_ERR(generic_phy);
dev_err(dev, "failed to create phy, %d\n", ret);
- pm_runtime_disable(dev);
return ret;
}
qphy->phy = generic_phy;

- dev_set_drvdata(dev, qphy);
phy_set_drvdata(generic_phy, qphy);

phy_provider = devm_of_phy_provider_register(dev, of_phy_simple_xlate);
- if (IS_ERR(phy_provider))
- pm_runtime_disable(dev);

return PTR_ERR_OR_ZERO(phy_provider);
}
--
2.51.0