linux-kernel - [PATCH 1/2] PCI: rcar: Fix use-after-free in probe error path

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Message-Id: <1512641720-4715-2-git-send-email-geert+renesas@glider.be>
Date:   Thu,  7 Dec 2017 11:15:19 +0100
From:   Geert Uytterhoeven <geert+renesas@...der.be>
To:     Simon Horman <horms@...ge.net.au>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Bjorn Helgaas <bhelgaas@...gle.com>
Cc:     Harunobu Kurokawa <harunobu.kurokawa.dn@...esas.com>,
        Phil Edworthy <phil.edworthy@...esas.com>,
        linux-pci@...r.kernel.org, linux-renesas-soc@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Geert Uytterhoeven <geert+renesas@...der.be>
Subject: [PATCH 1/2] PCI: rcar: Fix use-after-free in probe error path

If CONFIG_DEBUG_SLAB=y, and no PCIe card is inserted, the kernel crashes
during probe on r8a7791/koelsch:

    rcar-pcie fe000000.pcie: PCIe link down
    Unable to handle kernel paging request at virtual address 6b6b6b6b

(seeing this message requires earlycon and keep_bootcon).

Indeed, pci_free_host_bridge() frees the PCI host bridge, including the
embedded rcar_pcie object, so pci_free_resource_list() must not be
called afterwards.

To fix this, move the call to pci_free_resource_list() up, and update the
label name accordingly.

Fixes: ddd535f1ea3eb27e ("PCI: rcar: Fix memory leak when no PCIe card is inserted")
Signed-off-by: Geert Uytterhoeven <geert+renesas@...der.be>
---
 drivers/pci/host/pcie-rcar.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/pci/host/pcie-rcar.c b/drivers/pci/host/pcie-rcar.c
index 12796eccb2befd91..52ab3cb0a0bfe065 100644
--- a/drivers/pci/host/pcie-rcar.c
+++ b/drivers/pci/host/pcie-rcar.c
@@ -1128,12 +1128,12 @@ static int rcar_pcie_probe(struct platform_device *pdev)
 	err = rcar_pcie_get_resources(pcie);
 	if (err < 0) {
 		dev_err(dev, "failed to request resources: %d\n", err);
-		goto err_free_bridge;
+		goto err_free_resource_list;
 	}
 
 	err = rcar_pcie_parse_map_dma_ranges(pcie, dev->of_node);
 	if (err)
-		goto err_free_bridge;
+		goto err_free_resource_list;
 
 	pm_runtime_enable(dev);
 	err = pm_runtime_get_sync(dev);
@@ -1176,9 +1176,9 @@ static int rcar_pcie_probe(struct platform_device *pdev)
 err_pm_disable:
 	pm_runtime_disable(dev);
 
-err_free_bridge:
-	pci_free_host_bridge(bridge);
+err_free_resource_list:
 	pci_free_resource_list(&pcie->resources);
+	pci_free_host_bridge(bridge);
 
 	return err;
 }
-- 
2.7.4