Re: [PATCH] fbdev: arkfb: Request legacy VGA I/O region
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From: Kees Cook <kees@kernel.org>
Date: 2025-12-13 14:22:01
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dri-devel, lkml
On Sat, Dec 13, 2025 at 03:49:32PM +0000, Swaraj Gaikwad wrote:
The arkfb driver uses the legacy VGA I/O range (0x3c0+) but does not request it. This can cause conflicts with other drivers that try to reserve these ports.
Eek, nice catch!
quoted hunk ↗ jump to hunk
Fix this by using devm_request_region() during the probe function. This ensures the region is properly reserved and automatically released on driver detach. Signed-off-by: Swaraj Gaikwad <redacted> --- Compile-tested only on x86_64. drivers/video/fbdev/arkfb.c | 6 ++++++ 1 file changed, 6 insertions(+)diff --git a/drivers/video/fbdev/arkfb.c b/drivers/video/fbdev/arkfb.c index ec084323115f..24e4c20d1a32 100644 --- a/drivers/video/fbdev/arkfb.c +++ b/drivers/video/fbdev/arkfb.c@@ -1018,6 +1018,12 @@ static int ark_pci_probe(struct pci_dev *dev, const struct pci_device_id *id) pcibios_bus_to_resource(dev->bus, &vga_res, &bus_reg); + if (!devm_request_region(&dev->dev, vga_res.start, 64 * 1024, "arkfb-vga")) {
I was expecting to see vga_res.end as the third argument instead of repeating the open-coded value. -Kees
+ dev_err(info->device, "cannot reserve legacy VGA ports\n"); + rc = -EBUSY; + goto err_find_mode; + } + par->state.vgabase = (void __iomem *) (unsigned long) vga_res.start; /* FIXME get memsize */ base-commit: a859eca0e4cc96f63ff125dbe5388d961558b0e9 -- 2.52.0
-- Kees Cook