Debian: CVE-2024-47740: linux, linux-6.1 -- security update

Debian: CVE-2024-47740: linux, linux-6.1 -- security update

Severity

4

CVSS

(AV:L/AC:M/Au:N/C:P/I:P/A:P)

Published

10/21/2024

Created

11/12/2024

Added

11/11/2024

Modified

01/03/2025

Description

In the Linux kernel, the following vulnerability has been resolved: f2fs: Require FMODE_WRITE for atomic write ioctls The F2FS ioctls for starting and committing atomic writes check for inode_owner_or_capable(), but this does not give LSMs like SELinux or Landlock an opportunity to deny the write access - if the caller's FSUID matches the inode's UID, inode_owner_or_capable() immediately returns true. There are scenarios where LSMs want to deny a process the ability to write particular files, even files that the FSUID of the process owns; but this can currently partially be bypassed using atomic write ioctls in two ways: - F2FS_IOC_START_ATOMIC_REPLACE + F2FS_IOC_COMMIT_ATOMIC_WRITE can truncate an inode to size 0 - F2FS_IOC_START_ATOMIC_WRITE + F2FS_IOC_ABORT_ATOMIC_WRITE can revert changes another process concurrently made to a file Fix it by requiring FMODE_WRITE for these operations, just like for F2FS_IOC_MOVE_RANGE. Since any legitimate caller should only be using these ioctls when intending to write into the file, that seems unlikely to break anything.

Solution(s)

• debian-upgrade-linux
• debian-upgrade-linux-6-1

References

• https://attackerkb.com/topics/cve-2024-47740
• CVE - 2024-47740
• DLA-4008-1