release/5.2.40/PCI-Fix-pci_add_dma_alias-bitmask-size.patch

From de308ac8b5dae99f31759ca6f51826d741831e27 Mon Sep 17 00:00:00 2001
From: James Sewart <jamessewart@arista.com>
Date: Tue, 10 Dec 2019 15:51:33 -0600
Subject: [PATCH] PCI: Fix pci_add_dma_alias() bitmask size

commit f8bf2aeb651b3460a4b36fd7ba1ba1d31777d35c upstream.

The number of possible devfns is 256, but pci_add_dma_alias() allocated a
bitmap of size 255.  Fix this off-by-one error.

This fixes commits 338c3149a221 ("PCI: Add support for multiple DMA
aliases") and c6635792737b ("PCI: Allocate dma_alias_mask with
bitmap_zalloc()"), but I doubt it was possible to see a problem because
it takes 4 64-bit longs (or 8 32-bit longs) to hold 255 bits, and
bitmap_zalloc() doesn't save the 255-bit size anywhere.

[bhelgaas: commit log, move #define to drivers/pci/pci.h, include loop
limit fix from Qian Cai:
https://lore.kernel.org/r/20191218170004.5297-1-cai@lca.pw]
Signed-off-by: James Sewart <jamessewart@arista.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Logan Gunthorpe <logang@deltatee.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 58c945caa438..55e7c6948bd1 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -5860,7 +5860,7 @@ EXPORT_SYMBOL_GPL(pci_pr3_present);
 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/pci.h b/drivers/pci/pci.h
index 9cb99380c61e..8923436a671d 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -4,6 +4,9 @@
 
 #include <linux/pci.h>
 
+/* Number of possible devfns: 0.0 to 1f.7 inclusive */
+#define MAX_NR_DEVFNS 256
+
 #define PCI_FIND_CAP_TTL	48
 
 #define PCI_VSEC_ID_INTEL_TBT	0x1234	/* Thunderbolt */
diff --git a/drivers/pci/search.c b/drivers/pci/search.c
index 5c7922612733..68326e5849da 100644
--- a/drivers/pci/search.c
+++ b/drivers/pci/search.c
@@ -42,9 +42,9 @@ int pci_for_each_dma_alias(struct pci_dev *pdev,
 	 * DMA, iterate over that too.
 	 */
 	if (unlikely(pdev->dma_alias_mask)) {
-		u8 devfn;
+		unsigned int 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)
-- 
2.7.4