[PATCH v2] PCI: quirks: Fix out-of-bounds MMIO read in nvme_disable_and_flr()

[Mohamad Raizudeen]

In nvme_disable_and_flr(), the PCI bar is mapped using
NVME_REG_CC + sizeof(cfg) which is (0x14 + 4 = 0x18 bytes)

However, the function later reads the controller status from
NVME_REG_CSTS - offset 0x1C, which is outside the mapped 0x18 byte
boundary. Reading past the mapped MMIO region is undefined behavior and
can return invalid data.

Fix this by increasing the mapping size to include NVME_REG_CSTS.

Fixes: ffb0863426eb9 ("PCI: Disable Samsung SM961/PM961 NVMe before FLR")
Signed-off-by: Mohamad Raizudeen <raizudeen.kerneldev@xxxxxxxxx>
---
Changes in v2:
- Changed the commit message to avoid overstating the risk as pointed
  out by Alex Williamson, to be more accurate about the actual behavior.

 drivers/pci/quirks.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
index b09f27f7846f..ed03892cc960 100644
--- a/drivers/pci/quirks.c
+++ b/drivers/pci/quirks.c
@@ -4090,7 +4090,7 @@ static int nvme_disable_and_flr(struct pci_dev *dev, bool probe)
 	if (probe)
 		return 0;
 
-	bar = pci_iomap(dev, 0, NVME_REG_CC + sizeof(cfg));
+	bar = pci_iomap(dev, 0, NVME_REG_CSTS + sizeof(cfg));
 	if (!bar)
 		return -ENOTTY;
 
-- 
2.53.0