Re: [PATCH v2] HID: amd_sfh: Validate PCI BAR size before mapping

[Jiri Kosina]

On Mon, 14 Sep 2026, Slawomir Stepien wrote:

> The amd_sfh driver maps PCI BAR 2 using pcim_iomap_regions() and
> subsequently accesses MMIO registers at offsets up to 0x10958 (e.g.,
> AMD_P2C_MSG3 at 0x1068C). However, the driver never validates that the BAR
> size is large enough to cover these accesses. If the driver is bound to a
> device with a smaller BAR 2, this leads to an out-of-bounds memory access
> and a page fault during the probe function.
> 
> For example, a page fault can occur when reading from privdata->mmio +
> AMD_P2C_MSG3 in mp2_select_ops():
> 
>   BUG: unable to handle page fault for address: ffffc9000390368c
>   PGD 100000067 P4D 100000067 PUD 1012c1067 PMD 105b64067 PTE 0
>   Oops: Oops: 0000 [#1] SMP KASAN NOPTI
>   RIP: 0010:readl arch/x86/include/asm/io.h:59 [inline]
>   RIP: 0010:mp2_select_ops drivers/hid/amd-sfh-hid/amd_sfh_pcie.c:282
>   [inline]
>   RIP: 0010:amd_mp2_pci_probe+0x337/0x5f0
>   drivers/hid/amd-sfh-hid/amd_sfh_pcie.c:487
>   Call Trace:
>    <TASK>
>    local_pci_probe drivers/pci/pci-driver.c:332 [inline]
>    pci_call_probe drivers/pci/pci-driver.c:394 [inline]
>    __pci_device_probe drivers/pci/pci-driver.c:455 [inline]
>    pci_device_probe+0x431/0xc90 drivers/pci/pci-driver.c:489
> 
> Fix this by verifying that the length of BAR 2 is at least 128KB before
> attempting to map it. Since the maximum accessed offset is 0x10958, and PCI
> BAR sizes are powers of 2, any legitimate hardware will have a BAR size of
> at least 128KB.
> 
> Fixes: 4f567b9f8141 ("SFH: PCIe driver to add support of AMD sensor fusion hub")
> Assisted-by: Gemini:gemini-3.7-flash Gemini:gemini-3.1-pro-preview syzbot
> Reported-by: syzbot+4eadd4dfe9e66522bae8@xxxxxxxxxxxxxxxxxxxxxxxxx
> Closes: https://syzkaller.appspot.com/bug?extid=4eadd4dfe9e66522bae8
> Link: https://syzkaller.appspot.com/ai_job?id=3bc1c45c-548f-4ab5-8243-d2c8ec321d6c
> Signed-off-by: Slawomir Stepien <sst@xxxxxxxxx>
> Acked-by: Basavaraj Natikar <Basavaraj.Natikar@xxxxxxx>
> ---
> v2:
> * Use SZ_128K for AMD_SFH_MIN_BAR_SIZE define
> * Add comment why we need 128K
> * Add 'Acked-by: Basavaraj Natikar <Basavaraj.Natikar@xxxxxxx>' since no logical changes
> 
> v1:
> * https://lore.kernel.org/all/94704655-d654-4500-8122-b80bea9bd908@xxxxxxxxxxxxxxx/

Applied, thanks.

-- 
Jiri Kosina
SUSE Labs