[PATCH] pinctrl: qcom: fix a use-after-free bug in system shutdown path

[Bartosz Golaszewski]

msm_pinctrl_probe() allocates the pctrl structure via devm_kzalloc() and
unconditionally populates the global variables poweroff_pctrl and
pm_power_off.

If msm_pinctrl_probe() subsequently fails, devres resources - including
the memory allocated for pctrl - are automatically freed. However, the
global pointers are never cleared, resulting in a use-after-free during
kernel_power_off().

Schedule a devres action clearing the global pointers that runs before
the pctrl memory is freed.

Cc: stable@xxxxxxxxxxxxxxx
Closes: https://sashiko.dev/#/bug/linux-0c3a18a4-3de8-489b-abc9-e9e3a8641ed2
Fixes: ad64498762dd ("pinctrl: qcom: Hook pm_power_down for shutdown support")
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@xxxxxxxxxxxxxxxx>
---
 drivers/pinctrl/qcom/pinctrl-msm.c | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/drivers/pinctrl/qcom/pinctrl-msm.c b/drivers/pinctrl/qcom/pinctrl-msm.c
index 32aa7b919e24a0e614078ddc70a248c746e4813b..6ddbec7c27664b5b137ae1bdf668dd88a0f5e224 100644
--- a/drivers/pinctrl/qcom/pinctrl-msm.c
+++ b/drivers/pinctrl/qcom/pinctrl-msm.c
@@ -1561,9 +1561,15 @@ static void msm_ps_hold_poweroff(void)
 	msm_ps_hold_restart(&data);
 }
 
+static void msm_pinctrl_clear_poweroff(void *data)
+{
+	poweroff_pctrl = NULL;
+	pm_power_off = NULL;
+}
+
 static void msm_pinctrl_setup_pm_reset(struct msm_pinctrl *pctrl)
 {
-	int i;
+	int i, ret;
 	const struct pinfunction *func = pctrl->soc->functions;
 
 	for (i = 0; i < pctrl->soc->nfunctions; i++)
@@ -1577,6 +1583,13 @@ static void msm_pinctrl_setup_pm_reset(struct msm_pinctrl *pctrl)
 					"failed to setup restart handler.\n");
 			poweroff_pctrl = pctrl;
 			pm_power_off = msm_ps_hold_poweroff;
+
+			ret = devm_add_action_or_reset(pctrl->dev,
+					msm_pinctrl_clear_poweroff, NULL);
+			if (ret)
+				dev_err(pctrl->dev,
+					"Failed to register the poweroff cleanup action.\n");
+
 			break;
 		}
 }

---
base-commit: ddfe51b0a0f5dc9e415cc2c8ad8db17532dd426b
change-id: 20261105-pinctrl-qcom-uaf-500115513a62

Best regards,
-- 
Bartosz Golaszewski <bartosz.golaszewski@xxxxxxxxxxxxxxxx>