CVE-2023-52609 binder: fix race between mmput() and do_exit()

2024-03-1810:07:45

Linux

github.com

linux kernel

vulnerability

binder

race

mmput

do_exit

mmget_not_zero

mmput_async

cleanup

deadlock

6.7 Medium

AI Score

Confidence

Low

0.0004 Low

EPSS

Percentile

13.1%

JSON

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

binder: fix race between mmput() and do_exit()

Task A calls binder_update_page_range() to allocate and insert pages on
a remote address space from Task B. For this, Task A pins the remote mm
via mmget_not_zero() first. This can race with Task B do_exit() and the
final mmput() refcount decrement will come from Task A.

In this case, the work of ____fput() from Task B is queued up in Task A
as TWA_RESUME. So in theory, Task A returns to userspace and the cleanup
work gets executed. However, Task A instead sleep, waiting for a reply
from Task B that never comes (it’s dead).

This means the binder_deferred_release() is blocked until an unrelated
binder event forces Task A to go back to userspace. All the associated
death notifications will also be delayed until then.

In order to fix this use mmput_async() that will schedule the work in
the corresponding mm->async_put_work WQ instead of Task A.

CNA Affected

[
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "unaffected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "drivers/android/binder_alloc.c"
    ],
    "versions": [
      {
        "version": "457b9a6f09f0",
        "lessThan": "95b1d336b064",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "457b9a6f09f0",
        "lessThan": "252a2a5569eb",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "457b9a6f09f0",
        "lessThan": "7e7a0d86542b",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "457b9a6f09f0",
        "lessThan": "98fee5bee97a",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "457b9a6f09f0",
        "lessThan": "6696f76c32ff",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "457b9a6f09f0",
        "lessThan": "67f16bf2cc16",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "457b9a6f09f0",
        "lessThan": "77d210e8db4d",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "457b9a6f09f0",
        "lessThan": "9a9ab0d96362",
        "status": "affected",
        "versionType": "git"
      }
    ]
  },
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "affected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "drivers/android/binder_alloc.c"
    ],
    "versions": [
      {
        "version": "2.6.29",
        "status": "affected"
      },
      {
        "version": "0",
        "lessThan": "2.6.29",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "4.19.306",
        "lessThanOrEqual": "4.19.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.4.268",
        "lessThanOrEqual": "5.4.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.10.209",
        "lessThanOrEqual": "5.10.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.15.148",
        "lessThanOrEqual": "5.15.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.1.75",
        "lessThanOrEqual": "6.1.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.6.14",
        "lessThanOrEqual": "6.6.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.7.2",
        "lessThanOrEqual": "6.7.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.8",
        "lessThanOrEqual": "*",
        "status": "unaffected",
        "versionType": "original_commit_for_fix"
      }
    ]
  }
]