From f8ee579d53aca887d93f5f411462f25c085a5106 Mon Sep 17 00:00:00 2001
From: Russell King <rmk+kernel@armlinux.org.uk>
Date: Tue, 2 Feb 2021 17:07:46 +0000
Subject: [PATCH] PCI: pci-bridge-emul: Fix array overruns, improve safety
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Git-commit: f8ee579d53aca887d93f5f411462f25c085a5106
Patch-mainline: v5.12-rc1
References: git-fixes

We allow up to PCI_EXP_SLTSTA2 registers to be accessed, but the
pcie_cap_regs_behavior[] array only covers up to PCI_EXP_RTSTA.  Expand
this array to avoid walking off the end of it.

Do the same for pci_regs_behavior for consistency[], and add a
BUILD_BUG_ON() to also check the bridge->conf structure size.

Fixes: 23a5fba4d941 ("PCI: Introduce PCI bridge emulated config space common logic")
Link: https://lore.kernel.org/r/E1l6z9W-0006Re-MQ@rmk-PC.armlinux.org.uk
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Pali Rohár <pali@kernel.org>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/pci/pci-bridge-emul.c |   11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

--- a/drivers/pci/pci-bridge-emul.c
+++ b/drivers/pci/pci-bridge-emul.c
@@ -21,8 +21,9 @@
 #include "pci-bridge-emul.h"
 
 #define PCI_BRIDGE_CONF_END	PCI_STD_HEADER_SIZEOF
+#define PCI_CAP_PCIE_SIZEOF	(PCI_EXP_SLTSTA2 + 2)
 #define PCI_CAP_PCIE_START	PCI_BRIDGE_CONF_END
-#define PCI_CAP_PCIE_END	(PCI_CAP_PCIE_START + PCI_EXP_SLTSTA2 + 2)
+#define PCI_CAP_PCIE_END	(PCI_CAP_PCIE_START + PCI_CAP_PCIE_SIZEOF)
 
 struct pci_bridge_reg_behavior {
 	/* Read-only bits */
@@ -38,7 +39,8 @@ struct pci_bridge_reg_behavior {
 	u32 rsvd;
 };
 
-static const struct pci_bridge_reg_behavior pci_regs_behavior[] = {
+static const
+struct pci_bridge_reg_behavior pci_regs_behavior[PCI_STD_HEADER_SIZEOF / 4] = {
 	[PCI_VENDOR_ID / 4] = { .ro = ~0 },
 	[PCI_COMMAND / 4] = {
 		.rw = (PCI_COMMAND_IO | PCI_COMMAND_MEMORY |
@@ -173,7 +175,8 @@ static const struct pci_bridge_reg_behav
 	},
 };
 
-static const struct pci_bridge_reg_behavior pcie_cap_regs_behavior[] = {
+static const
+struct pci_bridge_reg_behavior pcie_cap_regs_behavior[PCI_CAP_PCIE_SIZEOF / 4] = {
 	[PCI_CAP_LIST_ID / 4] = {
 		/*
 		 * Capability ID, Next Capability Pointer and
@@ -270,6 +273,8 @@ static const struct pci_bridge_reg_behav
 int pci_bridge_emul_init(struct pci_bridge_emul *bridge,
 			 unsigned int flags)
 {
+	BUILD_BUG_ON(sizeof(bridge->conf) != PCI_BRIDGE_CONF_END);
+
 	bridge->conf.class_revision |= cpu_to_le32(PCI_CLASS_BRIDGE_PCI << 16);
 	bridge->conf.header_type = PCI_HEADER_TYPE_BRIDGE;
 	bridge->conf.cache_line_size = 0x10;