CVE-2024-40913

2024-07-1213:15:14

Linux

web.nvd.nist.gov

linux kernel

cachefiles

vulnerability

reference count

userland

close fd

uaf

copy_to_user

fd_install

AI Score

6.4

Confidence

Low

EPSS

Percentile

15.9%

JSON

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

cachefiles: defer exposing anon_fd until after copy_to_user() succeeds

After installing the anonymous fd, we can now see it in userland and close
it. However, at this point we may not have gotten the reference count of
the cache, but we will put it during colse fd, so this may cause a cache
UAF.

So grab the cache reference count before fd_install(). In addition, by
kernel convention, fd is taken over by the user land after fd_install(),
and the kernel should not call close_fd() after that, i.e., it should call
fd_install() after everything is ready, thus fd_install() is called after
copy_to_user() succeeds.

Affected configurations

Vulners

Node

linuxlinux_kernelRange5.19–6.1.95

linuxlinux_kernelRange6.2.0–6.6.35

linuxlinux_kernelRange6.7.0–6.9.6

linuxlinux_kernelRange6.10.0≥

VendorProductVersionCPE
linuxlinux_kernel*cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*

Vendor	Product	Version	CPE
linux	linux_kernel	*	cpe:2.3:o:linux:linux_kernel::::::::

CNA Affected

[
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "unaffected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "fs/cachefiles/ondemand.c"
    ],
    "versions": [
      {
        "version": "c8383054506c",
        "lessThan": "eac51d9daacd",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "c8383054506c",
        "lessThan": "d2d3eb377a5d",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "c8383054506c",
        "lessThan": "b9f58cdae6a3",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "c8383054506c",
        "lessThan": "4b4391e77a6b",
        "status": "affected",
        "versionType": "git"
      }
    ]
  },
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "affected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "fs/cachefiles/ondemand.c"
    ],
    "versions": [
      {
        "version": "5.19",
        "status": "affected"
      },
      {
        "version": "0",
        "lessThan": "5.19",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.1.95",
        "lessThanOrEqual": "6.1.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.6.35",
        "lessThanOrEqual": "6.6.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.9.6",
        "lessThanOrEqual": "6.9.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.10",
        "lessThanOrEqual": "*",
        "status": "unaffected",
        "versionType": "original_commit_for_fix"
      }
    ]
  }
]