linux-kernel - Re: [PATCH 12/42] PCI: aardvark: Check for virq mapping when processing INTx IRQ

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Date:   Fri, 07 May 2021 10:15:39 +0100
From:   Marc Zyngier <maz@...nel.org>
To:     Pali Rohár <pali@...nel.org>
Cc:     Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
        Rob Herring <robh@...nel.org>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Russell King <rmk+kernel@...linux.org.uk>,
        Marek Behún <kabel@...nel.org>,
        Remi Pommarel <repk@...plefau.lt>, Xogium <contact@...ium.me>,
        Tomasz Maciej Nowak <tmn505@...il.com>,
        linux-pci@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 12/42] PCI: aardvark: Check for virq mapping when processing INTx IRQ

On Thu, 06 May 2021 16:31:23 +0100,
Pali Rohár <pali@...nel.org> wrote:
> 
> It is possible that we receive spurious INTx interrupt. So add needed check
> before calling generic_handle_irq() function.
> 
> Signed-off-by: Pali Rohár <pali@...nel.org>
> Reviewed-by: Marek Behún <kabel@...nel.org>
> Cc: stable@...r.kernel.org
> ---
>  drivers/pci/controller/pci-aardvark.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/pci/controller/pci-aardvark.c b/drivers/pci/controller/pci-aardvark.c
> index 362faddae935..e7089db11f79 100644
> --- a/drivers/pci/controller/pci-aardvark.c
> +++ b/drivers/pci/controller/pci-aardvark.c
> @@ -1106,7 +1106,10 @@ static void advk_pcie_handle_int(struct advk_pcie *pcie)
>  			    PCIE_ISR1_REG);
>  
>  		virq = irq_find_mapping(pcie->irq_domain, i);
> -		generic_handle_irq(virq);
> +		if (virq)
> +			generic_handle_irq(virq);
> +		else
> +			dev_err(&pcie->pdev->dev, "unexpected INT%c IRQ\n", (char)i+'A');

Please don't scream like this. This is the best way to get into a DoS
situation if you interrupt rate is high enough. At least rate-limit
it.

	M.

-- 
Without deviation from the norm, progress is not possible.