CVE-2024-26712 powerpc/kasan: Fix addr error caused by page alignment

2024-04-0314:55:14

Linux

www.cve.org

linux kernel

vulnerability

powerpc

kasan

memory address

page alignment

memory overwriting

memblock_alloc

cve

7.5 High

AI Score

Confidence

High

0.0004 Low

EPSS

Percentile

10.4%

JSON

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

powerpc/kasan: Fix addr error caused by page alignment

In kasan_init_region, when k_start is not page aligned, at the begin of
for loop, k_cur = k_start & PAGE_MASK is less than k_start, and then
va = block + k_cur - k_start is less than block, the addr va is invalid,
because the memory address space from va to block is not alloced by
memblock_alloc, which will not be reserved by memblock_reserve later, it
will be used by other places.

As a result, memory overwriting occurs.

for example:
int __init __weak kasan_init_region(void start, size_t size)
{
[…]
/ if say block(dcd97000) k_start(feef7400) k_end(feeff3fe) /
block = memblock_alloc(k_end - k_start, PAGE_SIZE);
[…]
for (k_cur = k_start & PAGE_MASK; k_cur < k_end; k_cur += PAGE_SIZE) {
/ at the begin of for loop
* block(dcd97000) va(dcd96c00) k_cur(feef7000) k_start(feef7400)
* va(dcd96c00) is less than block(dcd97000), va is invalid
*/
void *va = block + k_cur - k_start;
[…]
}
[…]
}

Therefore, page alignment is performed on k_start before
memblock_alloc() to ensure the validity of the VA address.

CNA Affected

[
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "unaffected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "arch/powerpc/mm/kasan/init_32.c"
    ],
    "versions": [
      {
        "version": "663c0c9496a6",
        "lessThan": "230e89b5ad0a",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "663c0c9496a6",
        "lessThan": "2738e0aa2fb2",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "663c0c9496a6",
        "lessThan": "0c09912dd838",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "663c0c9496a6",
        "lessThan": "0516c06b19dc",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "663c0c9496a6",
        "lessThan": "70ef2ba1f428",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "663c0c9496a6",
        "lessThan": "4a7aee96200a",
        "status": "affected",
        "versionType": "git"
      }
    ]
  },
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "affected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "arch/powerpc/mm/kasan/init_32.c"
    ],
    "versions": [
      {
        "version": "5.4",
        "status": "affected"
      },
      {
        "version": "0",
        "lessThan": "5.4",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.10.210",
        "lessThanOrEqual": "5.10.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.15.149",
        "lessThanOrEqual": "5.15.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.1.79",
        "lessThanOrEqual": "6.1.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.6.18",
        "lessThanOrEqual": "6.6.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.7.6",
        "lessThanOrEqual": "6.7.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.8",
        "lessThanOrEqual": "*",
        "status": "unaffected",
        "versionType": "original_commit_for_fix"
      }
    ]
  }
]