Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Date:   Fri, 07 May 2021 10:15:39 +0100
Message-ID: <87h7jeq4zo.wl-maz@kernel.org>
From:   Marc Zyngier <maz@kernel.org>
To:     Pali =?UTF-8?B?Um9ow6Fy?= <pali@kernel.org>
Cc:     Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
        Thomas Petazzoni <thomas.petazzoni@bootlin.com>,
        Rob Herring <robh@kernel.org>,
        Bjorn Helgaas <bhelgaas@google.com>,
        Russell King <rmk+kernel@armlinux.org.uk>,
        Marek =?UTF-8?B?QmVow7pu?= <kabel@kernel.org>,
        Remi Pommarel <repk@triplefau.lt>, Xogium <contact@xogium.me>,
        Tomasz Maciej Nowak <tmn505@gmail.com>,
        linux-pci@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH 12/42] PCI: aardvark: Check for virq mapping when processing INTx IRQ
In-Reply-To: <20210506153153.30454-13-pali@kernel.org>
References: <20210506153153.30454-1-pali@kernel.org>
        <20210506153153.30454-13-pali@kernel.org>
User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue)
 FLIM-LB/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL-LB/10.8 EasyPG/1.0.0 Emacs/27.1
 (x86_64-pc-linux-gnu) MULE/6.0 (HANACHIRUSATO)
MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue")
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8BIT
Precedence: bulk

On Thu, 06 May 2021 16:31:23 +0100,
Pali Rohár <pali@kernel.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@kernel.org>
> Reviewed-by: Marek Behún <kabel@kernel.org>
> Cc: stable@vger.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.