linux-kernel - [PATCH v6 1/3] PCI: Fix off by one in dma_alias

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Message-Id: <910070E3-7964-4549-B77F-EC7FC6144503@arista.com>
Date:   Tue, 3 Dec 2019 15:43:22 +0000
From:   James Sewart <jamessewart@...sta.com>
To:     linux-pci@...r.kernel.org
Cc:     Logan Gunthorpe <logang@...tatee.com>,
        Christoph Hellwig <hch@...radead.org>,
        Dmitry Safonov <0x7f454c46@...il.com>,
        iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
        Dmitry Safonov <dima@...sta.com>,
        Alex Williamson <alex.williamson@...hat.com>,
        Bjorn Helgaas <helgaas@...nel.org>
Subject: [PATCH v6 1/3] PCI: Fix off by one in dma_alias_mask allocation size

The number of possible devfns is 256, add def and correct uses.

Reviewed-by: Logan Gunthorpe <logang@...tatee.com>
Signed-off-by: James Sewart <jamessewart@...sta.com>
---
 drivers/pci/pci.c    | 2 +-
 drivers/pci/search.c | 2 +-
 include/linux/pci.h  | 2 ++
 3 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index a97e2571a527..d3c83248f3ce 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -5876,7 +5876,7 @@ int pci_set_vga_state(struct pci_dev *dev, bool decode,
 void pci_add_dma_alias(struct pci_dev *dev, u8 devfn)
 {
 	if (!dev->dma_alias_mask)
-		dev->dma_alias_mask = bitmap_zalloc(U8_MAX, GFP_KERNEL);
+		dev->dma_alias_mask = bitmap_zalloc(MAX_NR_DEVFNS, GFP_KERNEL);
 	if (!dev->dma_alias_mask) {
 		pci_warn(dev, "Unable to allocate DMA alias mask\n");
 		return;
diff --git a/drivers/pci/search.c b/drivers/pci/search.c
index bade14002fd8..9e4dfae47252 100644
--- a/drivers/pci/search.c
+++ b/drivers/pci/search.c
@@ -43,7 +43,7 @@ int pci_for_each_dma_alias(struct pci_dev *pdev,
 	if (unlikely(pdev->dma_alias_mask)) {
 		u8 devfn;
 
-		for_each_set_bit(devfn, pdev->dma_alias_mask, U8_MAX) {
+		for_each_set_bit(devfn, pdev->dma_alias_mask, MAX_NR_DEVFNS) {
 			ret = fn(pdev, PCI_DEVID(pdev->bus->number, devfn),
 				 data);
 			if (ret)
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 1a6cf19eac2d..6481da29d667 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -57,6 +57,8 @@
 #define PCI_DEVID(bus, devfn)	((((u16)(bus)) << 8) | (devfn))
 /* return bus from PCI devid = ((u16)bus_number) << 8) | devfn */
 #define PCI_BUS_NUM(x) (((x) >> 8) & 0xff)
+/* Number of possible devfns. devfns can be from 0.0 to 1f.7 inclusive */
+#define MAX_NR_DEVFNS 256
 
 /* pci_slot represents a physical slot */
 struct pci_slot {
-- 
2.24.0