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

Sumit Gupta
2023-04-24T13:04:28Z

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@kernel.org>
>> Signed-off-by: Sumit Gupta <sumitg@nvidia.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@kernel.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
>>