CVE-2024-47740

Summary

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.

Affected Software

VendorProductVersion RangeStatus
LinuxLinux88b88a66797159949cec32eaab12b4968f6fae2d < 700f3a7c7fa5764c9f24bbf7c78e0b6e479fa653affected
LinuxLinux88b88a66797159949cec32eaab12b4968f6fae2d < 4ce87674c3a6b4d3b3d45f85b584ab8618a3ceceaffected
LinuxLinux88b88a66797159949cec32eaab12b4968f6fae2d < 000bab8753ae29a259feb339b99ee759795a48acaffected
LinuxLinux88b88a66797159949cec32eaab12b4968f6fae2d < 88ff021e1fea2d9b40b2d5efd9013c89f7be04acaffected
LinuxLinux88b88a66797159949cec32eaab12b4968f6fae2d < 32f348ecc149e9ca70a1c424ae8fa9b6919d2713affected
LinuxLinux88b88a66797159949cec32eaab12b4968f6fae2d < 5e0de753bfe87768ebe6744d869caa92f35e5731affected
LinuxLinux88b88a66797159949cec32eaab12b4968f6fae2d < f3bfac2cabf5333506b263bc0c8497c95302f32daffected
LinuxLinux88b88a66797159949cec32eaab12b4968f6fae2d < 4583290898c13c2c2e5eb8773886d153c2c5121daffected
LinuxLinux88b88a66797159949cec32eaab12b4968f6fae2d < 4f5a100f87f32cb65d4bb1ad282a08c92f6f591eaffected
LinuxLinux3.18affected
LinuxLinux0 < 3.18unaffected
LinuxLinux4.19.323 <= 4.19.*unaffected
LinuxLinux5.4.285 <= 5.4.*unaffected
LinuxLinux5.10.227 <= 5.10.*unaffected
LinuxLinux5.15.168 <= 5.15.*unaffected
LinuxLinux6.1.113 <= 6.1.*unaffected
LinuxLinux6.6.54 <= 6.6.*unaffected
LinuxLinux6.10.13 <= 6.10.*unaffected
LinuxLinux6.11.2 <= 6.11.*unaffected
LinuxLinux6.12 <= *unaffected

Weaknesses

ADP Enrichment

CISA ADP Vulnrichment

  • SSVC:
  • Exploitation: none
    • Automatable: no
    • Technical Impact: partial

CVE Program Container

Additional References

References