[PATCH] PCI: imx6: Avoid dereferencing a NULL clock name

[PATCH] PCI: imx6: Avoid dereferencing a NULL clock name

[Rudi Heitbaum]

of_clk_bulk_get() leaves clk_bulk_data::id as NULL for every clock that
has no matching entry in "clock-names", which is legal: a node may list
more "clocks" phandles than it names. The extref scan dereferences that
id unconditionally, so such a node oopses during probe.

Check clk_bulk_data::id before dereferencing it.

Fixes: d8574ce57d76 ("PCI: imx6: Add external reference clock input mode support")
Cc: stable@vger.kernel.org
Signed-off-by: Rudi Heitbaum <rudi@heitbaum.com>
---
 drivers/pci/controller/dwc/pci-imx6.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/pci/controller/dwc/pci-imx6.c b/drivers/pci/controller/dwc/pci-imx6.c
index f7389b5437df..dcdeba1856f7 100644
--- a/drivers/pci/controller/dwc/pci-imx6.c
+++ b/drivers/pci/controller/dwc/pci-imx6.c
@@ -1831,7 +1831,8 @@ static int imx_pcie_probe(struct platform_device *pdev)
 		return dev_err_probe(dev, imx_pcie->num_clks,
 				     "failed to get clocks\n");
 	for (i = 0; i < imx_pcie->num_clks; i++)
-		if (strncmp(imx_pcie->clks[i].id, "extref", 6) == 0)
+		if (imx_pcie->clks[i].id &&
+		    strncmp(imx_pcie->clks[i].id, "extref", 6) == 0)
 			imx_pcie->enable_ext_refclk = true;
 
 	if (imx_check_flag(imx_pcie, IMX_PCIE_FLAG_HAS_PHYDRV)) {
-- 
2.53.0

Re: [PATCH] PCI: imx6: Avoid dereferencing a NULL clock name

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:

Pre-existing issues:
- [High] The patch successfully fixes a NULL pointer dereference in `imx_pcie_probe()` by checking `imx_pcie->clks[i].id` before passing it to `strncmp()`, but it misses an identical preexisting vulnerability in `imx_setup_phy_mpll()`.
--

--- Patch [1]: [PATCH] PCI: imx6: Avoid dereferencing a NULL clock name ---
commit 59f2384c27b018977b395ad505a6ac37e2ecf39a
Author: Rudi Heitbaum <rudi@heitbaum.com>

PCI: imx6: Avoid dereferencing a NULL clock name
    
This patch fixes a kernel oops in imx_pcie_probe() by checking if
clk_bulk_data::id is NULL before passing it to strncmp(). This happens
because of_clk_bulk_get() legally leaves the id as NULL for unnamed clocks.

> diff --git a/drivers/pci/controller/dwc/pci-imx6.c b/drivers/pci/controller/dwc/pci-imx6.c
> index 98e1db751132a..9a9efc2ab894a 100644
> --- a/drivers/pci/controller/dwc/pci-imx6.c
> +++ b/drivers/pci/controller/dwc/pci-imx6.c
> @@ -1826,7 +1826,8 @@ static int imx_pcie_probe(struct platform_device *pdev)
>  		return dev_err_probe(dev, imx_pcie->num_clks,
>  				     "failed to get clocks\n");
>  	for (i = 0; i < imx_pcie->num_clks; i++)
> -		if (strncmp(imx_pcie->clks[i].id, "extref", 6) == 0)
> +		if (imx_pcie->clks[i].id &&
> +		    strncmp(imx_pcie->clks[i].id, "extref", 6) == 0)
>  			imx_pcie->enable_ext_refclk = true;
>  
>  	if (imx_check_flag(imx_pcie, IMX_PCIE_FLAG_HAS_PHYDRV)) {

[Severity: High]
This is a pre-existing issue, but this same vulnerability appears to exist
elsewhere in this driver.

In imx_setup_phy_mpll(), the driver iterates over the clocks and calls
strncmp() on the id without checking if it is NULL:

drivers/pci/controller/dwc/pci-imx6.c:imx_setup_phy_mpll() {
    ...
	for (i = 0; i < imx_pcie->num_clks; i++)
		if (strncmp(clks[i].id, "pcie_phy", 8) == 0)
			phy_rate = clk_get_rate(clks[i].clk);
    ...
}

Could this cause a similar oops during probe when IMX_PCIE_FLAG_IMX_PHY is
used and an unnamed clock is present? Would it make sense to apply the same
NULL check to this loop?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/am8iBwJSEhYhWTqk@6cfee64030a6?part=1

RE: [PATCH] PCI: imx6: Avoid dereferencing a NULL clock name

[Hongxing Zhu]

> -----Original Message-----
> From: Rudi Heitbaum <rudi@heitbaum.com>
> Sent: Sunday, August 2, 2026 6:55 PM
> To: Hongxing Zhu <hongxing.zhu@nxp.com>; Lucas Stach
> <l.stach@pengutronix.de>
> Cc: Lorenzo Pieralisi <lpieralisi@kernel.org>; Krzysztof Wilczyński
> <kwilczynski@kernel.org>; Manivannan Sadhasivam <mani@kernel.org>; Rob
> Herring <robh@kernel.org>; Bjorn Helgaas <bhelgaas@google.com>; linux-
> pci@vger.kernel.org; linux-arm-kernel@lists.infradead.org; imx@lists.linux.dev;
> linux-kernel@vger.kernel.org; stable@vger.kernel.org; rudi@heitbaum.com
> Subject: [PATCH] PCI: imx6: Avoid dereferencing a NULL clock name
> 
> [You don't often get email from rudi@heitbaum.com. Learn why this is important
> at https://aka.ms/LearnAboutSenderIdentification ]
> 
> of_clk_bulk_get() leaves clk_bulk_data::id as NULL for every clock that has no
> matching entry in "clock-names", which is legal: a node may list more "clocks"
> phandles than it names. The extref scan dereferences that id unconditionally, so
> such a node oopses during probe.
> 
> Check clk_bulk_data::id before dereferencing it.
> 
> Fixes: d8574ce57d76 ("PCI: imx6: Add external reference clock input mode
> support")
> Cc: stable@vger.kernel.org
> Signed-off-by: Rudi Heitbaum <rudi@heitbaum.com>
Good catch.
This isn't triggered in my daily tests, but the fix is correct.
Thanks for this fix.
Acked-by: Richard Zhu <hongxing.zhu@nxp.com>

Best Regards
Richard Zhu
> ---
>  drivers/pci/controller/dwc/pci-imx6.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/pci/controller/dwc/pci-imx6.c
> b/drivers/pci/controller/dwc/pci-imx6.c
> index f7389b5437df..dcdeba1856f7 100644
> --- a/drivers/pci/controller/dwc/pci-imx6.c
> +++ b/drivers/pci/controller/dwc/pci-imx6.c
> @@ -1831,7 +1831,8 @@ static int imx_pcie_probe(struct platform_device
> *pdev)
>                 return dev_err_probe(dev, imx_pcie->num_clks,
>                                      "failed to get clocks\n");
>         for (i = 0; i < imx_pcie->num_clks; i++)
> -               if (strncmp(imx_pcie->clks[i].id, "extref", 6) == 0)
> +               if (imx_pcie->clks[i].id &&
> +                   strncmp(imx_pcie->clks[i].id, "extref", 6) == 0)
>                         imx_pcie->enable_ext_refclk = true;
> 
>         if (imx_check_flag(imx_pcie, IMX_PCIE_FLAG_HAS_PHYDRV)) {
> --
> 2.53.0