linux-kernel - Re: [Patch v6 7/9] PCI: tegra194: Fix possible array out of bounds access

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Message-ID: <c247a72c-5e69-09ed-e7a6-c87a410f392c@nvidia.com>
Date:   Mon, 24 Apr 2023 18:33:38 +0530
From:   Sumit Gupta <sumitg@...dia.com>
To:     Lorenzo Pieralisi <lpieralisi@...nel.org>
CC:     <treding@...dia.com>, <krzysztof.kozlowski@...aro.org>,
        <dmitry.osipenko@...labora.com>, <viresh.kumar@...aro.org>,
        <rafael@...nel.org>, <jonathanh@...dia.com>, <robh+dt@...nel.org>,
        <helgaas@...nel.org>, <linux-kernel@...r.kernel.org>,
        <linux-tegra@...r.kernel.org>, <linux-pm@...r.kernel.org>,
        <devicetree@...r.kernel.org>, <linux-pci@...r.kernel.org>,
        <mmaddireddy@...dia.com>, <kw@...ux.com>, <bhelgaas@...gle.com>,
        <vidyas@...dia.com>, <sanjayc@...dia.com>, <ksitaraman@...dia.com>,
        <ishah@...dia.com>, <bbasu@...dia.com>,
        Sumit Gupta <sumitg@...dia.com>
Subject: Re: [Patch v6 7/9] PCI: tegra194: Fix possible array out of bounds
 access



On 21/04/23 18:42, Lorenzo Pieralisi wrote:
> External email: Use caution opening links or attachments
> 
> 
> On Tue, Apr 11, 2023 at 04:30:00PM +0530, Sumit Gupta wrote:
>> Add check to fix the possible array out of bounds violation by
>> making speed equal to GEN1_CORE_CLK_FREQ when its value is more
>> than the size of "pcie_gen_freq" array. This array has size of
>> four but possible speed (CLS) values are from "0 to 0xF". So,
>> "speed - 1" values are "-1 to 0xE". This change was suggested by
>> "Bjorn Helgaas" in the below link.
> 
> There is a Suggested-by tag and a Link: tag remove the last
> sentence, that's duplicate information.
> 
Removed in v7.

Thank you,
Sumit Gupta

>> Suggested-by: Bjorn Helgaas <helgaas@...nel.org>
>> Signed-off-by: Sumit Gupta <sumitg@...dia.com>
>> Link: https://lore.kernel.org/lkml/72b9168b-d4d6-4312-32ea-69358df2f2d0@nvidia.com/
>> ---
>>   drivers/pci/controller/dwc/pcie-tegra194.c | 13 +++++++++++--
>>   1 file changed, 11 insertions(+), 2 deletions(-)
> 
> Acked-by: Lorenzo Pieralisi <lpieralisi@...nel.org>
> 
>> diff --git a/drivers/pci/controller/dwc/pcie-tegra194.c b/drivers/pci/controller/dwc/pcie-tegra194.c
>> index 09825b4a075e..e6eec85480ca 100644
>> --- a/drivers/pci/controller/dwc/pcie-tegra194.c
>> +++ b/drivers/pci/controller/dwc/pcie-tegra194.c
>> @@ -223,6 +223,7 @@
>>   #define EP_STATE_ENABLED     1
>>
>>   static const unsigned int pcie_gen_freq[] = {
>> +     GEN1_CORE_CLK_FREQ,     /* PCI_EXP_LNKSTA_CLS == 0; undefined */
>>        GEN1_CORE_CLK_FREQ,
>>        GEN2_CORE_CLK_FREQ,
>>        GEN3_CORE_CLK_FREQ,
>> @@ -459,7 +460,11 @@ static irqreturn_t tegra_pcie_ep_irq_thread(int irq, void *arg)
>>
>>        speed = dw_pcie_readw_dbi(pci, pcie->pcie_cap_base + PCI_EXP_LNKSTA) &
>>                PCI_EXP_LNKSTA_CLS;
>> -     clk_set_rate(pcie->core_clk, pcie_gen_freq[speed - 1]);
>> +
>> +     if (speed >= ARRAY_SIZE(pcie_gen_freq))
>> +             speed = 0;
>> +
>> +     clk_set_rate(pcie->core_clk, pcie_gen_freq[speed]);
>>
>>        if (pcie->of_data->has_ltr_req_fix)
>>                return IRQ_HANDLED;
>> @@ -1020,7 +1025,11 @@ static int tegra_pcie_dw_start_link(struct dw_pcie *pci)
>>
>>        speed = dw_pcie_readw_dbi(pci, pcie->pcie_cap_base + PCI_EXP_LNKSTA) &
>>                PCI_EXP_LNKSTA_CLS;
>> -     clk_set_rate(pcie->core_clk, pcie_gen_freq[speed - 1]);
>> +
>> +     if (speed >= ARRAY_SIZE(pcie_gen_freq))
>> +             speed = 0;
>> +
>> +     clk_set_rate(pcie->core_clk, pcie_gen_freq[speed]);
>>
>>        tegra_pcie_enable_interrupts(pp);
>>
>> --
>> 2.17.1
>>