linux-kernel - [patch v2] vfio/pci: make an array larger

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Message-ID: <20151109122455.GA28870@mwanda>
Date:	Mon, 9 Nov 2015 15:24:55 +0300
From:	Dan Carpenter <dan.carpenter@...cle.com>
To:	Alex Williamson <alex.williamson@...hat.com>,
	"Sean O. Stalley" <sean.stalley@...el.com>
Cc:	Mark Rustad <mark.d.rustad@...el.com>, kvm@...r.kernel.org,
	linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org
Subject: [patch v2] vfio/pci: make an array larger

Smatch complains about a possible out of bounds error:

	drivers/vfio/pci/vfio_pci_config.c:1241 vfio_cap_init()
	error: buffer overflow 'pci_cap_length' 20 <= 20

The problem is that pci_cap_length[] was defined as large enough to
hold "PCI_CAP_ID_AF + 1" elements.  The code in vfio_cap_init() assumes
it has PCI_CAP_ID_MAX + 1 elements.  Originally, PCI_CAP_ID_AF and
PCI_CAP_ID_MAX were the same but then we introduced PCI_CAP_ID_EA in
f80b0ba95964 ('PCI: Add Enhanced Allocation register entries') so now
the array is too small.

Let's fix this by making the array size PCI_CAP_ID_MAX + 1.  And let's
make a similar change to pci_ext_cap_length[] for consistency.  Also
both these arrays can be made const.

Signed-off-by: Dan Carpenter <dan.carpenter@...cle.com>
---
v2: more cleanups

diff --git a/drivers/vfio/pci/vfio_pci_config.c b/drivers/vfio/pci/vfio_pci_config.c
index a8657ef..fe2b470 100644
--- a/drivers/vfio/pci/vfio_pci_config.c
+++ b/drivers/vfio/pci/vfio_pci_config.c
@@ -46,7 +46,7 @@
  *   0: Removed from the user visible capability list
  *   FF: Variable length
  */
-static u8 pci_cap_length[] = {
+static const u8 pci_cap_length[PCI_CAP_ID_MAX + 1] = {
 	[PCI_CAP_ID_BASIC]	= PCI_STD_HEADER_SIZEOF, /* pci config header */
 	[PCI_CAP_ID_PM]		= PCI_PM_SIZEOF,
 	[PCI_CAP_ID_AGP]	= PCI_AGP_SIZEOF,
@@ -74,7 +74,7 @@ static u8 pci_cap_length[] = {
  *   0: Removed or masked from the user visible capabilty list
  *   FF: Variable length
  */
-static u16 pci_ext_cap_length[] = {
+static const u16 pci_ext_cap_length[PCI_EXT_CAP_ID_MAX + 1] = {
 	[PCI_EXT_CAP_ID_ERR]	=	PCI_ERR_ROOT_COMMAND,
 	[PCI_EXT_CAP_ID_VC]	=	0xFF,
 	[PCI_EXT_CAP_ID_DSN]	=	PCI_EXT_CAP_DSN_SIZEOF,
--
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