linux-kernel - Re: [PATCH v4] x86/PCI: fix a memory leak bug

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Message-ID: <20190417203514.GT126710@google.com>
Date:   Wed, 17 Apr 2019 15:35:14 -0500
From:   Bjorn Helgaas <helgaas@...nel.org>
To:     Wenwen Wang <wang6495@....edu>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>,
        "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" <x86@...nel.org>,
        "open list:PCI SUBSYSTEM" <linux-pci@...r.kernel.org>,
        "open list:X86 ARCHITECTURE (32-BIT AND 64-BIT)" 
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v4] x86/PCI: fix a memory leak bug

On Wed, Apr 17, 2019 at 09:18:50AM -0500, Wenwen Wang 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 is a memory
> leak bug.
> 
> To fix this issue, free the allocated table if it is not used.
> 
> Signed-off-by: Wenwen Wang <wang6495@....edu>
> Acked-by: Thomas Gleixner <tglx@...utronix.de>

I added Ingo's reviewed-by (since the only change from v1 was to make the
local variable name change he suggested) and applied this to pci/misc for
v5.2, thanks!

> ---
>  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
>