Re: [PATCH] PCI: sysfs: Reject unaligned resource I/O port accesses

[Manivannan Sadhasivam]

On Sun, Aug 09, 2026 at 10:29:46AM +0530, Deepanshu Kartikey wrote:
> pci_resource_io() validates that off+count stays within the BAR's
> range but never checks that the resulting port is aligned to the
> access size. A pwrite64()/pread64() on a resourceN file with an odd
> offset and count=2 or count=4 reaches outw()/outl() with a misaligned
> address. On arm64 this becomes a store/load to a Device-memory
> mapping (PCI_IOBASE + port), which architecturally requires natural
> alignment, causing an alignment fault and kernel oops.
> 
> Reject misaligned accesses before they reach the low-level accessor.
> 
> Reported-by: syzbot+7134530b25073b4ef373@xxxxxxxxxxxxxxxxxxxxxxxxx
> Closes: https://syzkaller.appspot.com/bug?extid=7134530b25073b4ef373
> Signed-off-by: Deepanshu Kartikey <kartikey406@xxxxxxxxx>

Acked-by: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxxxxxxxx>

- Mani

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