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

* Wenwen Wang <wang6495@umn.edu> wrote:

> 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 <wang6495@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..d9bcb96 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 *itable = NULL;
> +

Minor style nit: the canonical name of irq_routing_table local variables
is usually 'rtable' or 'rt' - let's not add a third naming variant with
'itable'?

> 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();
> + itable = 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(itable);
> pirq_table = NULL;
> + }

Reviewed-by: Ingo Molnar <mingo@kernel.org>

Thanks,

Ingo

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