Bug 2373491 (CVE-2022-49964)

Summary: CVE-2022-49964 kernel: arm64: cacheinfo: Fix incorrect assignment of signed error value to unsigned fw_level
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
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Priority: medium    
Version: unspecifiedCC: dfreiber, drow, jburrell, vkumar
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Hardware: All   
OS: Linux   
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Description OSIDB Bzimport 2025-06-18 12:05:18 UTC
In the Linux kernel, the following vulnerability has been resolved:

arm64: cacheinfo: Fix incorrect assignment of signed error value to unsigned fw_level

Though acpi_find_last_cache_level() always returned signed value and the
document states it will return any errors caused by lack of a PPTT table,
it never returned negative values before.

Commit 0c80f9e165f8 ("ACPI: PPTT: Leave the table mapped for the runtime usage")
however changed it by returning -ENOENT if no PPTT was found. The value
returned from acpi_find_last_cache_level() is then assigned to unsigned
fw_level.

It will result in the number of cache leaves calculated incorrectly as
a huge value which will then cause the following warning from __alloc_pages
as the order would be great than MAX_ORDER because of incorrect and huge
cache leaves value.

  |  WARNING: CPU: 0 PID: 1 at mm/page_alloc.c:5407 __alloc_pages+0x74/0x314
  |  Modules linked in:
  |  CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.19.0-10393-g7c2a8d3ac4c0 #73
  |  pstate: 20000005 (nzCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
  |  pc : __alloc_pages+0x74/0x314
  |  lr : alloc_pages+0xe8/0x318
  |  Call trace:
  |   __alloc_pages+0x74/0x314
  |   alloc_pages+0xe8/0x318
  |   kmalloc_order_trace+0x68/0x1dc
  |   __kmalloc+0x240/0x338
  |   detect_cache_attributes+0xe0/0x56c
  |   update_siblings_masks+0x38/0x284
  |   store_cpu_topology+0x78/0x84
  |   smp_prepare_cpus+0x48/0x134
  |   kernel_init_freeable+0xc4/0x14c
  |   kernel_init+0x2c/0x1b4
  |   ret_from_fork+0x10/0x20

Fix the same by changing fw_level to be signed integer and return the
error from init_cache_level() early in case of error.

Comment 1 Avinash Hanwate 2025-06-19 23:11:39 UTC
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2025061815-CVE-2022-49964-ff03@gregkh/T