Description
In the Linux kernel, the following vulnerability has been resolved:

ALSA: usx2y: bound the hwdep mmap fault offset

snd_us428ctls_vm_fault() turns the faulting page offset into a kernel
address with no bound of any kind:

offset = vmf->pgoff << PAGE_SHIFT;
vaddr = (char *)(...)->us428ctls_sharedmem + offset;
page = virt_to_page(vaddr);
get_page(page);
vmf->page = page;

return 0;

snd_us428ctls_mmap() checks only the length of the mapping, never the
offset, and us428ctls_sharedmem is a single page from
alloc_pages_exact(). For a character device file_mmap_size_max()
returns ULONG_MAX, so the mm layer imposes no ceiling either. Every page
offset above zero resolves to a struct page outside the object, and the
handler installs it into the caller's address space read-write; the vma
is not marked read-only.

The caller picks the page frame with a single mmap() argument and gets
read-write access to a page of kernel memory it does not own; an offset
that lands in an unpopulated vmemmap region oopses instead.

A process that can open the hwdep node of an attached US-X2Y reaches
this after loading the FPGA image through the same node; no capability
check is involved.

On 7.2.0-rc5 (arm64), mmap() with a large offset:

Unable to handle kernel paging request at virtual address fffffdffc45d5ac8
pc : snd_us428ctls_vm_fault+0x68/0x140 [snd_usb_usx2y]
Call trace:
snd_us428ctls_vm_fault+0x68/0x140 [snd_usb_usx2y]
__do_fault
__handle_mm_fault
handle_mm_fault
el0_da

Reject any offset outside the shared region. The pcm hwdep handler in
usx2yhwdeppcm.c computes its address the same way and needs the same
bound.

Discovered by XBOW, triaged by Baul Lee <baul.lee@xbow.com>
Published: 2026-08-22
Score: n/a
EPSS: n/a
KEV: No
Impact: n/a
Action: n/a
AI Analysis

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Remediation

No vendor fix or workaround currently provided.

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History

Sat, 22 Aug 2026 15:45:00 +0000

Type Values Removed Values Added
Description In the Linux kernel, the following vulnerability has been resolved: ALSA: usx2y: bound the hwdep mmap fault offset snd_us428ctls_vm_fault() turns the faulting page offset into a kernel address with no bound of any kind: offset = vmf->pgoff << PAGE_SHIFT; vaddr = (char *)(...)->us428ctls_sharedmem + offset; page = virt_to_page(vaddr); get_page(page); vmf->page = page; return 0; snd_us428ctls_mmap() checks only the length of the mapping, never the offset, and us428ctls_sharedmem is a single page from alloc_pages_exact(). For a character device file_mmap_size_max() returns ULONG_MAX, so the mm layer imposes no ceiling either. Every page offset above zero resolves to a struct page outside the object, and the handler installs it into the caller's address space read-write; the vma is not marked read-only. The caller picks the page frame with a single mmap() argument and gets read-write access to a page of kernel memory it does not own; an offset that lands in an unpopulated vmemmap region oopses instead. A process that can open the hwdep node of an attached US-X2Y reaches this after loading the FPGA image through the same node; no capability check is involved. On 7.2.0-rc5 (arm64), mmap() with a large offset: Unable to handle kernel paging request at virtual address fffffdffc45d5ac8 pc : snd_us428ctls_vm_fault+0x68/0x140 [snd_usb_usx2y] Call trace: snd_us428ctls_vm_fault+0x68/0x140 [snd_usb_usx2y] __do_fault __handle_mm_fault handle_mm_fault el0_da Reject any offset outside the shared region. The pcm hwdep handler in usx2yhwdeppcm.c computes its address the same way and needs the same bound. Discovered by XBOW, triaged by Baul Lee <baul.lee@xbow.com>
Title ALSA: usx2y: bound the hwdep mmap fault offset
First Time appeared Linux
Linux linux Kernel
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Vendors & Products Linux
Linux linux Kernel
References

Subscriptions

Linux Linux Kernel
cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published:

Updated: 2026-08-22T15:32:19.696Z

Reserved: 2026-08-15T05:44:03.922Z

Link: CVE-2026-74641

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-08-22T16:16:37.383

Modified: 2026-08-22T16:16:37.383

Link: CVE-2026-74641

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-08-22T17:15:04Z

Weaknesses

No weakness.