CVE-2024-38605 ALSA: core: Fix NULL module pointer assignment at card init

2024-06-1913:48:15

Linux

www.cve.org

linux kernel

alsa

core fix

null module pointer

card init

module assignment

0.0004 Low

EPSS

Percentile

10.4%

JSON

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

ALSA: core: Fix NULL module pointer assignment at card init

The commit 81033c6b584b (“ALSA: core: Warn on empty module”)
introduced a WARN_ON() for a NULL module pointer passed at snd_card
object creation, and it also wraps the code around it with ‘#ifdef
MODULE’. This works in most cases, but the devils are always in
details. “MODULE” is defined when the target code (i.e. the sound
core) is built as a module; but this doesn’t mean that the caller is
also built-in or not. Namely, when only the sound core is built-in
(CONFIG_SND=y) while the driver is a module (CONFIG_SND_USB_AUDIO=m),
the passed module pointer is ignored even if it’s non-NULL, and
card->module remains as NULL. This would result in the missing module
reference up/down at the device open/close, leading to a race with the
code execution after the module removal.

For addressing the bug, move the assignment of card->module again out
of ifdef. The WARN_ON() is still wrapped with ifdef because the
module can be really NULL when all sound drivers are built-in.

Note that we keep ‘ifdef MODULE’ for WARN_ON(), otherwise it would
lead to a false-positive NULL module check. Admittedly it won’t catch
perfectly, i.e. no check is performed when CONFIG_SND=y. But, it’s no
real problem as it’s only for debugging, and the condition is pretty
rare.

CNA Affected

[
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "unaffected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "sound/core/init.c"
    ],
    "versions": [
      {
        "version": "81033c6b584b",
        "lessThan": "d7ff29a429b5",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "81033c6b584b",
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    ]
  },
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "affected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "sound/core/init.c"
    ],
    "versions": [
      {
        "version": "5.9",
        "status": "affected"
      },
      {
        "version": "0",
        "lessThan": "5.9",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.10.219",
        "lessThanOrEqual": "5.10.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.15.161",
        "lessThanOrEqual": "5.15.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.1.93",
        "lessThanOrEqual": "6.1.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.6.33",
        "lessThanOrEqual": "6.6.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.8.12",
        "lessThanOrEqual": "6.8.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.9.3",
        "lessThanOrEqual": "6.9.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.10-rc1",
        "lessThanOrEqual": "*",
        "status": "unaffected",
        "versionType": "original_commit_for_fix"
      }
    ]
  }
]