CVE-2024-40935

2024-07-1213:15:16

Linux

web.nvd.nist.gov

linux kernel

vulnerability

cachefiles

flush requests

cachefiles_dead

ondemand mode

kernel flags

cachefiles_daemon_write

hung_task

irreversible

cachefiles_io_error

reference counting

uaf

AI Score

6.2

Confidence

Low

EPSS

Percentile

15.9%

JSON

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

cachefiles: flush all requests after setting CACHEFILES_DEAD

In ondemand mode, when the daemon is processing an open request, if the
kernel flags the cache as CACHEFILES_DEAD, the cachefiles_daemon_write()
will always return -EIO, so the daemon can’t pass the copen to the kernel.
Then the kernel process that is waiting for the copen triggers a hung_task.

Since the DEAD state is irreversible, it can only be exited by closing
/dev/cachefiles. Therefore, after calling cachefiles_io_error() to mark
the cache as CACHEFILES_DEAD, if in ondemand mode, flush all requests to
avoid the above hungtask. We may still be able to read some of the cached
data before closing the fd of /dev/cachefiles.

Note that this relies on the patch that adds reference counting to the req,
otherwise it may UAF.

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/daemon.c",
      "fs/cachefiles/internal.h"
    ],
    "versions": [
      {
        "version": "c8383054506c",
        "lessThan": "320ba9cbca78",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "c8383054506c",
        "lessThan": "3bf0b8030296",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "c8383054506c",
        "lessThan": "e73fac950848",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "c8383054506c",
        "lessThan": "85e833cd7243",
        "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/daemon.c",
      "fs/cachefiles/internal.h"
    ],
    "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"
      }
    ]
  }
]