CVE-2024-56565

/// Technical description

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 paramet

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References