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🛡️ CVE-2024-50217 — kernel

🟠 CVSS 7.8 — High ✅ No Known Exploit NVD
7.8
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

btrfs: fix use-after-free of block device file in __btrfs_free_extra_devids()

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

btrfs: fix use-after-free of block device file in __btrfs_free_extra_devids()

Mounting btrfs from two images (which have the same one fsid and two

different dev_uuids) in certain executing order may trigger an UAF for

variable 'device->bdev_file' in __btrfs_free_extra_devids(). And

following are the details:

1. Attach image_1 to loop0, attach image_2 to loop1, and scan btrfs

devices by ioctl(BTRFS_IOC_SCAN_DEV):

/ btrfs_device_1 → loop0

fs_device

\ btrfs_device_2 → loop1

2. mount /dev/loop0 /mnt

btrfs_open_devices

btrfs_device_1->bdev_file = btrfs_get_bdev_and_sb(loop0)

btrfs_device_2->bdev_file = btrfs_get_bdev_and_sb(loop1)

btrfs_fill_super

open_ctree

fail: btrfs_close_devices // -ENOMEM

btrfs_close_bdev(btrfs_device_1)

fput(btrfs_device_1->bdev_file)

// btrfs_device_1->bdev_file is freed

btrfs_close_bdev(btrfs_device_2)

fput(btrfs_device_2->bdev_file)

3. mount /dev/loop1 /mnt

btrfs_open_devices

btrfs_get_bdev_and_sb(&bdev_file)

// EIO, btrfs_device_1->bdev_file is not assigned,

// which points to a freed memory area

btrfs_device_2->bdev_file = btrfs_get_bdev_and_sb(loop1)

btrfs_fill_super

open_ctree

btrfs_free_extra_devids

if (btrfs_device_1->bdev_file)

fput(btrfs_device_1->bdev_file) // UAF !

Fix it by setting 'device->bdev_file' as 'NULL' after closing the

btrfs_device in btrfs_close_one_device().

How this vulnerability can be exploited

This issue can be reached with local access to the system, attack complexity is low, an attacker needs no privileges on the target. A user must be tricked into taking some action. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality high, integrity high, availability high.

Affected software

CVE-2024-50217 is recorded against 2 packages.

  • kernel (from 4.8.0 up to 6.11.7)
  • linux-kernel

Timeline and source

Published on 9 November 2024 and last revised on 12 August 2026. No public exploit is currently recorded for this entry. A vendor advisory or fix has been published. Record sourced from NVD.

References

www.openwall.com (Web)
www.openwall.com (Web)
www.openwall.com (Web)
git.kernel.org (Web)
git.kernel.org (Web)
github.com (Advisory)
nvd.nist.gov (Advisory)
git.kernel.org (Package)

CVE-2024-50217 on other distributions

Each distribution ships its own build and its own fixed version. Pick the one you run:

Details

Severity High
CVSS Score 7.8
CVSS Vector CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
CWE N/A
Public Exploit ✅ No
Source NVD
Published 2024-11-09
Updated 2026-08-20
Modified 2026-08-12

Affected Packages

Software From version Fixed in
kernel 4.8.0 6.11.7
linux-kernel — —

Similar Threats

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