[PATCH v2] x86/PCI: fix a memory leak bug

[Wenwen Wang]

In pcibios_irq_init(), the PCI IRQ routing table 'pirq_table' is firstly
found through pirq_find_routing_table(). If the table is not found and
'CONFIG_PCI_BIOS' is defined, the table is then allocated in
pcibios_get_irq_routing_table() using kmalloc(). In the following
execution, if the I/O APIC is used, this table is actually not used.
However, in that case, the allocated table is not freed, which can lead to
a memory leak bug.

To fix this issue, this patch frees the allocated table if it is not used.

Signed-off-by: Wenwen Wang <wang6...@umn.edu>
---
 arch/x86/pci/irq.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/arch/x86/pci/irq.c b/arch/x86/pci/irq.c
index 52e5510..d3a73f9 100644
--- a/arch/x86/pci/irq.c
+++ b/arch/x86/pci/irq.c
@@ -1119,6 +1119,8 @@ static const struct dmi_system_id pciirq_dmi_table[] 
__initconst = {
 
 void __init pcibios_irq_init(void)
 {
+       struct irq_routing_table *rtable = NULL;
+
        DBG(KERN_DEBUG "PCI: IRQ init\n");
 
        if (raw_pci_ops == NULL)
@@ -1129,8 +1131,10 @@ void __init pcibios_irq_init(void)
        pirq_table = pirq_find_routing_table();
 
 #ifdef CONFIG_PCI_BIOS
-       if (!pirq_table && (pci_probe & PCI_BIOS_IRQ_SCAN))
+       if (!pirq_table && (pci_probe & PCI_BIOS_IRQ_SCAN)) {
                pirq_table = pcibios_get_irq_routing_table();
+               rtable = pirq_table;
+       }
 #endif
        if (pirq_table) {
                pirq_peer_trick();
@@ -1145,8 +1149,10 @@ void __init pcibios_irq_init(void)
                 * If we're using the I/O APIC, avoid using the PCI IRQ
                 * routing table
                 */
-               if (io_apic_assign_pci_irqs)
+               if (io_apic_assign_pci_irqs) {
+                       kfree(rtable);
                        pirq_table = NULL;
+               }
        }
 
        x86_init.pci.fixup_irqs();
-- 
2.7.4