[PATCH MANUALSEL 5.4 4/4] x86/PCI: Add PIRQ routing table range checks

[Sasha Levin]

From: "Maciej W. Rozycki" <macro@xxxxxxxxxxx>

[ Upstream commit 5d64089aa4a5bd3d7e00e3d6ddf4943dd34627b3 ]

Verify that the PCI IRQ Routing Table header as well as individual slot
entries are all wholly contained within the BIOS memory area.  Do not
even call the checksum calculator if the header would overrun the area
and then bail out early if any slot would.

Signed-off-by: Maciej W. Rozycki <macro@xxxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/alpine.DEB.2.21.2203301735510.22465@xxxxxxxxxxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 arch/x86/pci/irq.c | 17 ++++++++++++-----
 1 file changed, 12 insertions(+), 5 deletions(-)

diff --git a/arch/x86/pci/irq.c b/arch/x86/pci/irq.c
index d3a73f9335e1..2bf6d2c4874b 100644
--- a/arch/x86/pci/irq.c
+++ b/arch/x86/pci/irq.c
@@ -62,7 +62,8 @@ void (*pcibios_disable_irq)(struct pci_dev *dev) = pirq_disable_irq;
  *  and perform checksum verification.
  */
 
-static inline struct irq_routing_table *pirq_check_routing_table(u8 *addr)
+static inline struct irq_routing_table *pirq_check_routing_table(u8 *addr,
+								 u8 *limit)
 {
 	struct irq_routing_table *rt;
 	int i;
@@ -72,7 +73,8 @@ static inline struct irq_routing_table *pirq_check_routing_table(u8 *addr)
 	if (rt->signature != PIRQ_SIGNATURE ||
 	    rt->version != PIRQ_VERSION ||
 	    rt->size % 16 ||
-	    rt->size < sizeof(struct irq_routing_table))
+	    rt->size < sizeof(struct irq_routing_table) ||
+	    (limit && rt->size > limit - addr))
 		return NULL;
 	sum = 0;
 	for (i = 0; i < rt->size; i++)
@@ -93,17 +95,22 @@ static inline struct irq_routing_table *pirq_check_routing_table(u8 *addr)
 
 static struct irq_routing_table * __init pirq_find_routing_table(void)
 {
+	u8 * const bios_start = (u8 *)__va(0xf0000);
+	u8 * const bios_end = (u8 *)__va(0x100000);
 	u8 *addr;
 	struct irq_routing_table *rt;
 
 	if (pirq_table_addr) {
-		rt = pirq_check_routing_table((u8 *) __va(pirq_table_addr));
+		rt = pirq_check_routing_table((u8 *)__va(pirq_table_addr),
+					      NULL);
 		if (rt)
 			return rt;
 		printk(KERN_WARNING "PCI: PIRQ table NOT found at pirqaddr\n");
 	}
-	for (addr = (u8 *) __va(0xf0000); addr < (u8 *) __va(0x100000); addr += 16) {
-		rt = pirq_check_routing_table(addr);
+	for (addr = bios_start;
+	     addr < bios_end - sizeof(struct irq_routing_table);
+	     addr += 16) {
+		rt = pirq_check_routing_table(addr, bios_end);
 		if (rt)
 			return rt;
 	}
-- 
2.35.1