[PATCH] ata: pata_sl82c105: fix bridge revision use-after-free

[Hongyan Xu <getshell@seu.edu.cn>]

pci_get_slot() returns a referenced PCI device. Commit 44c10138fd4b
("PCI: Change all drivers to use pci_device->revision") replaced a
configuration-space read with direct access to the cached revision field,
but left that access after pci_dev_put(). The bridge may therefore be freed
before its revision is read.

Read the revision before dropping the reference.

Fixes: 44c10138fd4b ("PCI: Change all drivers to use pci_device->revision")
Signed-off-by: Hongyan Xu <getshell@seu.edu.cn>
---
 drivers/ata/pata_sl82c105.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/ata/pata_sl82c105.c b/drivers/ata/pata_sl82c105.c
index 2d24c6b3e9d9..25bce3fe2a10 100644
--- a/drivers/ata/pata_sl82c105.c
+++ b/drivers/ata/pata_sl82c105.c
@@ -264,6 +264,7 @@ static struct ata_port_operations sl82c105_port_ops = {
 static int sl82c105_bridge_revision(struct pci_dev *pdev)
 {
 	struct pci_dev *bridge;
+	u8 revision;
 
 	/*
 	 * The bridge should be part of the same device, but function 0.
@@ -285,8 +286,9 @@ static int sl82c105_bridge_revision(struct pci_dev *pdev)
 	/*
 	 * We need to find function 0's revision, not function 1
 	 */
+	revision = bridge->revision;
 	pci_dev_put(bridge);
-	return bridge->revision;
+	return revision;
 }
 
 static void sl82c105_fixup(struct pci_dev *pdev)
-- 
2.50.1.windows.1