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

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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@xxxxxxxxxx>
Signed-off-by: Sumit Gupta <sumitg@xxxxxxxxxx>
Link: https://lore.kernel.org/lkml/72b9168b-d4d6-4312-32ea-69358df2f2d0@xxxxxxxxxx/
---
  drivers/pci/controller/dwc/pcie-tegra194.c | 13 +++++++++++--
  1 file changed, 11 insertions(+), 2 deletions(-)

Acked-by: Lorenzo Pieralisi <lpieralisi@xxxxxxxxxx>

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




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