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🛡️ CVE-2024-56565 — kernel

🟡 CVSS 5.5 — Medium ✅ No Known Exploit NVD
5.5
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

f2fs: fix to drop all discards after creating snapshot on lvm device

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

f2fs: fix to drop all discards after creating snapshot on lvm device

Piergiorgio reported a bug in bugzilla as below:

------------[ cut here ]------------

WARNING: CPU: 2 PID: 969 at fs/f2fs/segment.c:1330

RIP: 0010:__submit_discard_cmd+0x27d/0x400 [f2fs]

Call Trace:

__issue_discard_cmd+0x1ca/0x350 [f2fs]

issue_discard_thread+0x191/0x480 [f2fs]

kthread+0xcf/0x100

ret_from_fork+0x31/0x50

ret_from_fork_asm+0x1a/0x30

w/ below testcase, it can reproduce this bug quickly:

  • pvcreate /dev/vdb
  • vgcreate myvg1 /dev/vdb
  • lvcreate -L 1024m -n mylv1 myvg1
  • mount /dev/myvg1/mylv1 /mnt/f2fs
  • dd if=/dev/zero of=/mnt/f2fs/file bs=1M count=20
  • sync
  • rm /mnt/f2fs/file
  • sync
  • lvcreate -L 1024m -s -n mylv1-snapshot /dev/myvg1/mylv1
  • umount /mnt/f2fs

The root cause is: it will update discard_max_bytes of mounted lvm

device to zero after creating snapshot on this lvm device, then,

__submit_discard_cmd() will pass parameter @nr_sects w/ zero value

to __blkdev_issue_discard(), it returns a NULL bio pointer, result

in panic.

This patch changes as below for fixing:

1. Let's drop all remained discards in f2fs_unfreeze() if snapshot

of lvm device is created.

2. Checking discard_max_bytes before submitting discard during

__submit_discard_cmd().

How this vulnerability can be exploited

This issue can be reached with local access to the system, attack complexity is low, an attacker needs low-level privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality none, integrity none, availability high.

CVSS metrics in full

The score comes from this vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

  • Attack vector: Local — a local account, shell or session on the host is needed.
  • Attack complexity: Low — the attack works reliably, with no preparation.
  • Privileges required: Low — an ordinary user account is enough.
  • User interaction: None — nobody has to be tricked into anything.
  • Scope: Unchanged — the damage stays inside the vulnerable component.
  • Confidentiality impact: None.
  • Integrity impact: None.
  • Availability impact: High — total loss, or loss the attacker controls.

Affected software

CVE-2024-56565 is recorded against 2 packages.

  • kernel (from 6.7.0 up to 6.12.4)
  • linux-kernel (from 6.7 up to 6.12.4)

Timeline and source

Published on 27 December 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

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

Other advisories for this package

kernel has other advisories on record. If you are patching this one, these are worth checking on the same host:

Details

Severity Medium
CVSS Score 5.5
CVSS Vector CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
CWE N/A
Public Exploit ✅ No
Source NVD
Published 2024-12-27
Updated 2026-08-20
Modified 2026-08-12

Affected Packages

Software From version Fixed in
kernel 6.7.0 6.12.4
linux-kernel 6.7 6.12.4

Similar Threats

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