Linux KernelOperating system · Linux

CVE-2024-47740

MEDIUM · 5.5 CVSS v3.1 Published 2024-10-21
Fix available
A fix is available. Upgrade to 4.19.323 / 5.4.285 or later.
See remediation →
57/100
Remediation priority · Elevated
Zero-click Patch available

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis

A detailed technical summary for this CVE is being prepared.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Linux KernelOperating system
Affected:>= 3.18, < 4.19.323>= 4.20, < 5.4.285>= 5.5, < 5.10.227>= 5.11, < 5.15.168>= 5.16, < 6.1.113>= 6.2, < 6.6.54>= 6.7, < 6.10.13>= 6.11, < 6.11.2

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Local
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 4.19.323 / 5.4.285 / 5.10.227 or later
Fixed in 4.19.3235.4.2855.10.227
Vendor patch git.kernel.org →
Recommended fix High confidence

Upgrade to kernel 4.19.323+ (for 4.19.x), 5.4.285+ (for 5.4.x), 5.10.227+ (for 5.10.x), or 5.15.168+ (for 5.15.x) - choose the nearest stable release in your branch

  1. Obtain the kernel source code for your currently running kernel version
  2. Locate the file fs/f2fs/file.c (or equivalent file containing F2FS ioctl handlers)
  3. Apply the patch from commit 000bab8753ae29a259feb339b99ee759795a48ac which adds FMODE_WRITE check to the atomic write ioctls (F2FS_IOC_START_ATOMIC_REPLACE, F2FS_IOC_COMMIT_ATOMIC_WRITE, F2FS_IOC_START_ATOMIC_WRITE, F2FS_IOC_ABORT_ATOMIC_WRITE)
  4. Alternatively, if your distribution provides kernel updates, apply the security update for your specific kernel version
  5. Rebuild the kernel or install the updated kernel package
  6. Reboot the system to load the patched kernel
Caveat Kernel upgrades may require rebuilding out-of-tree modules; ensure driver compatibility before upgrading

Generated from the published advisory — verify against the referenced sources before acting.

We can perform the upgrade in your staging environment and verify nothing breaks — typical engagement from $1,600. Get the upgrade done

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2024-47740 in production — separate from our analysis above.

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