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 <[email protected]>

https://git.kernel.org/stable/c/10a87401fb3148c388e55df0148295b3b137da07

https://git.kernel.org/stable/c/2ca1eea3cd17930daffe9e429a7c89232036ec24

https://git.kernel.org/stable/c/34ab56ed854baa73a731cfd99af689f0b1bac444

https://git.kernel.org/stable/c/4208db2453e1ea71b8048a5b7802360cb29a53f1

https://git.kernel.org/stable/c/5bf5ccddf00b59f1e3ea7e65d76a5f5b5c21cc2e

https://git.kernel.org/stable/c/f613b4a2d87247b51a1b2b330f2e083a454125f2

https://git.kernel.org/stable/c/f75d6f61f0d9c5c1ea725104014e10d26d1e3a00

[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","programFiles":["sound/usb/usx2y/usX2Yhwdep.c","sound/usb/usx2y/usx2yhwdeppcm.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","versions":[{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","lessThan":"10a87401fb3148c388e55df0148295b3b137da07","versionType":"git","status":"affected"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","lessThan":"34ab56ed854baa73a731cfd99af689f0b1bac444","versionType":"git","status":"affected"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","lessThan":"4208db2453e1ea71b8048a5b7802360cb29a53f1","versionType":"git","status":"affected"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","lessThan":"f613b4a2d87247b51a1b2b330f2e083a454125f2","versionType":"git","status":"affected"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","lessThan":"f75d6f61f0d9c5c1ea725104014e10d26d1e3a00","versionType":"git","status":"affected"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","lessThan":"5bf5ccddf00b59f1e3ea7e65d76a5f5b5c21cc2e","versionType":"git","status":"affected"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","lessThan":"2ca1eea3cd17930daffe9e429a7c89232036ec24","versionType":"git","status":"affected"}]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","programFiles":["sound/usb/usx2y/usX2Yhwdep.c","sound/usb/usx2y/usx2yhwdeppcm.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","versions":[{"version":"2.6.12","status":"affected"},{"version":"0","lessThan":"2.6.12","versionType":"semver","status":"unaffected"},{"version":"5.15.216","lessThanOrEqual":"5.15.*","versionType":"semver","status":"unaffected"},{"version":"6.1.183","lessThanOrEqual":"6.1.*","versionType":"semver","status":"unaffected"},{"version":"6.6.152","lessThanOrEqual":"6.6.*","versionType":"semver","status":"unaffected"},{"version":"6.12.104","lessThanOrEqual":"6.12.*","versionType":"semver","status":"unaffected"},{"version":"6.18.45","lessThanOrEqual":"6.18.*","versionType":"semver","status":"unaffected"},{"version":"7.1.9","lessThanOrEqual":"7.1.*","versionType":"semver","status":"unaffected"},{"version":"7.2","lessThanOrEqual":"*","versionType":"original_commit_for_fix","status":"unaffected"}]}]