2019-04-15 14:57:47

by Wenwen Wang

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

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 <[email protected]>
---
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;
+
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;
+ }
}

x86_init.pci.fixup_irqs();
--
2.7.4

2019-04-16 07:24:26

by Ingo Molnar

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

* Wenwen Wang <[email protected]> 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 <[email protected]>
> ---
> 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 <[email protected]>

Thanks,

Ingo

2019-04-16 13:40:16

by Wenwen Wang

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

On Tue, Apr 16, 2019 at 2:23 AM Ingo Molnar <[email protected]> wrote:
>
>
> * Wenwen Wang <[email protected]> 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 <[email protected]>
> > ---
> > 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'?
>

Thanks for your comment! I will rework the patch.

Wenwen

> > 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 <[email protected]>
>
> Thanks,
>
> Ingo