[PATCH] arm_pmu: acpi: fix reference leak on failed device registration

[Guangshuo Li]

When platform_device_register() fails in arm_acpi_register_pmu_device(),
the embedded struct device in pdev has already been initialized by
device_initialize(), but the failure path only unregisters the GSI and
does not drop the device reference for the current platform device:

  arm_acpi_register_pmu_device()
    -> platform_device_register(pdev)
       -> device_initialize(&pdev->dev)
       -> setup_pdev_dma_masks(pdev)
       -> platform_device_add(pdev)

This leads to a reference leak when platform_device_register() fails.
Fix this by calling platform_device_put() after unregistering the GSI.

The issue was identified by a static analysis tool I developed and
confirmed by manual review.

Fixes: 81e5ee4716098 ("arm_pmu: acpi: Refactor arm_spe_acpi_register_device()")
Cc: stable at vger.kernel.org
Signed-off-by: Guangshuo Li <lgs201920130244 at gmail.com>
---
 drivers/perf/arm_pmu_acpi.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/perf/arm_pmu_acpi.c b/drivers/perf/arm_pmu_acpi.c
index e80f76d95e68..5ce382661e34 100644
--- a/drivers/perf/arm_pmu_acpi.c
+++ b/drivers/perf/arm_pmu_acpi.c
@@ -119,8 +119,10 @@ arm_acpi_register_pmu_device(struct platform_device *pdev, u8 len,
 
 	pdev->resource[0].start = irq;
 	ret = platform_device_register(pdev);
-	if (ret)
+	if (ret) {
 		acpi_unregister_gsi(gsi);
+		platform_device_put(pdev);
+	}
 
 	return ret;
 }
-- 
2.43.0