Re: [PATCH 10/20] alpha/PCI: Add security_locked_down() check to pci_mmap_resource()

Ilpo Järvinen
2026-04-10T11:04:35Z

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On Fri, 10 Apr 2026, Krzysztof Wilczyński wrote:

> Currently, Alpha's pci_mmap_resource() does not check
> security_locked_down(LOCKDOWN_PCI_ACCESS) before allowing
> userspace to mmap PCI BARs.
>
> The generic version has had this check since commit eb627e17727e
> ("PCI: Lock down BAR access when the kernel is locked down") to
> prevent DMA attacks when the kernel is locked down.
>
> Add the same check to Alpha's pci_mmap_resource().
>
> Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>

Maybe add Fixes: eb627e17727e ...

> ---
> arch/alpha/kernel/pci-sysfs.c | 7 ++++++-
> 1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/arch/alpha/kernel/pci-sysfs.c b/arch/alpha/kernel/pci-sysfs.c
> index 3048758304b5..2324720c3e83 100644
> --- a/arch/alpha/kernel/pci-sysfs.c
> +++ b/arch/alpha/kernel/pci-sysfs.c
> @@ -11,6 +11,7 @@
> */
>
> #include <linux/sched.h>
> +#include <linux/security.h>
> #include <linux/stat.h>
> #include <linux/slab.h>
> #include <linux/pci.h>
> @@ -71,7 +72,11 @@ static int pci_mmap_resource(struct kobject *kobj,
> struct resource *res = attr->private;
> enum pci_mmap_state mmap_type;
> struct pci_bus_region bar;
> - int i;
> + int i, ret;
> +
> + ret = security_locked_down(LOCKDOWN_PCI_ACCESS);
> + if (ret)
> + return ret;
>
> for (i = 0; i < PCI_STD_NUM_BARS; i++)
> if (res == &pdev->resource[i])
>

Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>

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