linux-kernel - Re: [PATCH] PCI: xilinx: Fix NULL pointer dereference

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Message-ID: <20250811222937.GA167215@bhelgaas>
Date: Mon, 11 Aug 2025 17:29:37 -0500
From: Bjorn Helgaas <helgaas@...nel.org>
To: Nam Cao <namcao@...utronix.de>
Cc: Lorenzo Pieralisi <lpieralisi@...nel.org>,
	Krzysztof Wilczyński <kwilczynski@...nel.org>,
	Manivannan Sadhasivam <mani@...nel.org>,
	Rob Herring <robh@...nel.org>, Bjorn Helgaas <bhelgaas@...gle.com>,
	Michal Simek <michal.simek@....com>,
	Thomas Gleixner <tglx@...utronix.de>, linux-pci@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] PCI: xilinx: Fix NULL pointer dereference

On Mon, Aug 11, 2025 at 07:41:44AM +0200, Nam Cao wrote:
> Commit f29861aa301c5 ("PCI: xilinx: Switch to
> msi_create_parent_irq_domain()") changed xilinx_pcie::msi_domain from child
> devices' interrupt domain into Xilinx AXI bridge's interrupt domain.
> 
> However, xilinx_pcie_intr_handler() wasn't changed and still reads Xilinx
> AXI bridge's interrupt domain from xilinx_pcie::msi_domain->parent. This
> pointer is NULL now.
> 
> Update xilinx_pcie_intr_handler() to read the correct interrupt domain
> pointer.
> 
> Fixes: f29861aa301c5 ("PCI: xilinx: Switch to msi_create_parent_irq_domain()")

Since this appeared in v6.17-rc1, I suppose this should be merged for
v6.17, right?  I provisionally put this on pci/for-linus for now.

What does this look like to a user?  I assume a NULL pointer
dereference in xilinx_pcie_intr_handler()?  Do you have a dmesg
snippet from hitting it?  It would be nice to include a couple lines
of that in the commit log to help users find this fix.

> Signed-off-by: Nam Cao <namcao@...utronix.de>
> ---
>  drivers/pci/controller/pcie-xilinx.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/pci/controller/pcie-xilinx.c b/drivers/pci/controller/pcie-xilinx.c
> index f121836c3cf4..937ea6ae1ac4 100644
> --- a/drivers/pci/controller/pcie-xilinx.c
> +++ b/drivers/pci/controller/pcie-xilinx.c
> @@ -400,7 +400,7 @@ static irqreturn_t xilinx_pcie_intr_handler(int irq, void *data)
>  		if (val & XILINX_PCIE_RPIFR1_MSI_INTR) {
>  			val = pcie_read(pcie, XILINX_PCIE_REG_RPIFR2) &
>  				XILINX_PCIE_RPIFR2_MSG_DATA;
> -			domain = pcie->msi_domain->parent;
> +			domain = pcie->msi_domain;
>  		} else {
>  			val = (val & XILINX_PCIE_RPIFR1_INTR_MASK) >>
>  				XILINX_PCIE_RPIFR1_INTR_SHIFT;
> -- 
> 2.39.5
>