CVE-2024-39482 bcache: fix variable length array abuse in btree_iter

2024-07-0506:55:10

Linux

github.com

linux kernel

vulnerability

bcache

btree_iter

array abuse

variable length

ubsan

patch

AI Score

6.9

Confidence

Low

EPSS

Percentile

5.1%

SSVC

Exploitation

none

Automatable

Technical Impact

partial

JSON

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

bcache: fix variable length array abuse in btree_iter

btree_iter is used in two ways: either allocated on the stack with a
fixed size MAX_BSETS, or from a mempool with a dynamic size based on the
specific cache set. Previously, the struct had a fixed-length array of
size MAX_BSETS which was indexed out-of-bounds for the dynamically-sized
iterators, which causes UBSAN to complain.

This patch uses the same approach as in bcachefs’s sort_iter and splits
the iterator into a btree_iter with a flexible array member and a
btree_iter_stack which embeds a btree_iter as well as a fixed-length
data array.

CNA Affected

[
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "1da177e4c3f4",
        "lessThan": "2c3d7b03b658",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "1da177e4c3f4",
        "lessThan": "5a1922adc579",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "1da177e4c3f4",
        "lessThan": "934e1e433185",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "1da177e4c3f4",
        "lessThan": "6479b9f41583",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "1da177e4c3f4",
        "lessThan": "0c31344e22dd",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "1da177e4c3f4",
        "lessThan": "3a861560ccb3",
        "versionType": "git"
      }
    ],
    "programFiles": [
      "drivers/md/bcache/bset.c",
      "drivers/md/bcache/bset.h",
      "drivers/md/bcache/btree.c",
      "drivers/md/bcache/super.c",
      "drivers/md/bcache/sysfs.c",
      "drivers/md/bcache/writeback.c"
    ],
    "defaultStatus": "unaffected"
  },
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "unaffected",
        "version": "5.10.221",
        "versionType": "custom",
        "lessThanOrEqual": "5.10.*"
      },
      {
        "status": "unaffected",
        "version": "5.15.162",
        "versionType": "custom",
        "lessThanOrEqual": "5.15.*"
      },
      {
        "status": "unaffected",
        "version": "6.1.94",
        "versionType": "custom",
        "lessThanOrEqual": "6.1.*"
      },
      {
        "status": "unaffected",
        "version": "6.6.34",
        "versionType": "custom",
        "lessThanOrEqual": "6.6.*"
      },
      {
        "status": "unaffected",
        "version": "6.9.5",
        "versionType": "custom",
        "lessThanOrEqual": "6.9.*"
      },
      {
        "status": "unaffected",
        "version": "6.10",
        "versionType": "original_commit_for_fix",
        "lessThanOrEqual": "*"
      }
    ],
    "programFiles": [
      "drivers/md/bcache/bset.c",
      "drivers/md/bcache/bset.h",
      "drivers/md/bcache/btree.c",
      "drivers/md/bcache/super.c",
      "drivers/md/bcache/sysfs.c",
      "drivers/md/bcache/writeback.c"
    ],
    "defaultStatus": "affected"
  }
]