[PATCH v2] perf/dwc_pcie: Fix PCI device reference leak in probe

[PATCH v2] perf/dwc_pcie: Fix PCI device reference leak in probe

[Ruoyu Wang]

pci_get_domain_bus_and_slot() returns a referenced PCI device. When the
subsequent RAS DES capability lookup fails, dwc_pcie_pmu_probe() returns
-ENODEV without releasing that reference. Repeated failed probes can
therefore keep the PCI device allocated after removal.

Declare the looked-up device with __free(pci_dev_put), so the temporary
reference is released on every return path. Keeping the reference scoped
to the whole probe also covers all later uses of the device during
initialization.

This issue was found by a static analysis checker and confirmed by manual
source review.

Fixes: 7f35b429802a ("perf/dwc_pcie: fix duplicate pci_dev devices")
Suggested-by: Markus Elfring <Markus.Elfring@web.de>
Signed-off-by: Ruoyu Wang <ruoyuw560@gmail.com>
---
Changes in v2:
- Manage the lookup reference with __free(pci_dev_put).
- Keep the reference scoped through the complete probe.

Link: https://lore.kernel.org/r/20260814133925.1385687-1-ruoyuw560@gmail.com/
---
 drivers/perf/dwc_pcie_pmu.c | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/drivers/perf/dwc_pcie_pmu.c b/drivers/perf/dwc_pcie_pmu.c
index 5385401fa9cf6..0e69bd71c3e61 100644
--- a/drivers/perf/dwc_pcie_pmu.c
+++ b/drivers/perf/dwc_pcie_pmu.c
@@ -694,16 +694,16 @@ static struct notifier_block dwc_pcie_pmu_nb = {
 
 static int dwc_pcie_pmu_probe(struct platform_device *plat_dev)
 {
-	struct pci_dev *pdev;
+	u32 sbdf = plat_dev->id;
+	struct pci_dev *pdev __free(pci_dev_put) =
+		pci_get_domain_bus_and_slot(sbdf >> 16,
+					    PCI_BUS_NUM(sbdf & 0xffff),
+					    sbdf & 0xff);
 	struct dwc_pcie_pmu *pcie_pmu;
 	char *name;
-	u32 sbdf;
 	u16 vsec;
 	int ret;
 
-	sbdf = plat_dev->id;
-	pdev = pci_get_domain_bus_and_slot(sbdf >> 16, PCI_BUS_NUM(sbdf & 0xffff),
-					   sbdf & 0xff);
 	if (!pdev) {
 		pr_err("No pdev found for the sbdf 0x%x\n", sbdf);
 		return -ENODEV;
@@ -713,7 +713,6 @@ static int dwc_pcie_pmu_probe(struct platform_device *plat_dev)
 	if (!vsec)
 		return -ENODEV;
 
-	pci_dev_put(pdev);
 	name = devm_kasprintf(&plat_dev->dev, GFP_KERNEL, "dwc_rootport_%x", sbdf);
 	if (!name)
 		return -ENOMEM;
-- 
2.51.0

Re: [PATCH v2] perf/dwc_pcie: Fix PCI device reference leak in probe

[Markus Elfring]

…
> Declare the looked-up device with __free(pci_dev_put), so the temporary
> reference is released on every return path. Keeping the reference scoped
> to the whole probe also covers all later uses of the device during
> initialization.
…

Is there a need to reduce the scope for such a local variable further
by using a corresponding compound statement?

Regards,
Markus

Re: [v2] perf/dwc_pcie: Fix PCI device reference leak in probe

[Markus Elfring]

> I think keeping the function scope is clearer here :)

I got an other impression because a pci_dev_put(pdev) call was applied
before a devm_kasprintf() call.
https://elixir.bootlin.com/linux/v7.2/source/drivers/perf/dwc_pcie_pmu.c#L695-L717

Regards,
Markus