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Linux KernelOperating system · Linux

CVE-2024-56678

HIGH · 7.8 CVSS v3.1 Published 2024-12-28
Fix available
A fix is available. Upgrade to 5.15.174 / 6.1.120 or later.
See remediation →
80/100
Remediation priority · High
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: powerpc/mm/fault: Fix kfence page fault reporting copy_from_kernel_nofault() can be called when doing read of /proc/kcore. /proc/kcore can have some unmapped kfence objects which when read via copy_from_kernel_nofault() can cause page faults. Since *_nofault() functions define their own fixup table for handling fault, use that instead of asking kfence to handle such faults. Hence we search the exception tables for the nip which generated the fault. If there is an entry then we let the fixup table handler handle the page fault by returning an error from within ___do_page_fault(). This can be easily triggered if someone tries to do dd from /proc/kcore. eg. dd if=/proc/kcore of=/dev/null bs=1M Some example false negatives: =============================== BUG: KFENCE: invalid read in copy_from_kernel_nofault+0x9c/0x1a0 Invalid read at 0xc0000000fdff0000: copy_from_kernel_nofault+0x9c/0x1a0 0xc00000000665f950 read_kcore_iter+0x57c/0xa04 proc_reg_read_iter+0xe4/0x16c vfs_read+0x320/0x3ec ksys_read+0x90/0x154 system_call_exception+0x120/0x310 system_call_vectored_common+0x15c/0x2ec BUG: KFENCE: use-after-free read in copy_from_kernel_nofault+0x9c/0x1a0 Use-after-free read at 0xc0000000fe050000 (in kfence-#2): copy_from_kernel_nofault+0x9c/0x1a0 0xc00000000665f950 read_kcore_iter+0x57c/0xa04 proc_reg_read_iter+0xe4/0x16c vfs_read+0x320/0x3ec ksys_read+0x90/0x154 system_call_exception+0x120/0x310 system_call_vectored_common+0x15c/0x2ec

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
How this class of weakness works · CWE-416

Memory is used after it has been freed, so its contents — now potentially attacker-controlled — drive the program's behaviour. With careful heap grooming this becomes code execution. The fix requires disciplined ownership of memory and often a targeted rework of the object lifecycle.

General guidance for the use after free class — the official description and references above are authoritative for this specific CVE. Want a bespoke review and a reviewed fix? Ask our team →

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:>= 5.13, < 5.15.174>= 5.16, < 6.1.120>= 6.2, < 6.6.64>= 6.7, < 6.11.11>= 6.12, < 6.12.2

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
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/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 5.15.174 / 6.1.120 / 6.6.64 or later
Fixed in 5.15.1746.1.1206.6.64
Vendor patch git.kernel.org →
Recommended fix High confidence

Upgrade to kernel 5.15.174 (if on 5.13-5.15.x), 6.1.120 (if on 5.16-6.1.x), 6.6.64 (if on 6.2-6.6.x), or 6.11.11 (if on 6.7-6.11.x)

  1. Identify the currently running kernel version using `uname -r`
  2. Check which version range your current kernel falls into (>= 5.13 and < 5.15.174, >= 5.16 and < 6.1.120, >= 6.2 and < 6.6.64, or >= 6.7 and < 6.11.11)
  3. Obtain the fixed kernel package for your distribution that corresponds to the next stable release: 5.15.174, 6.1.120, 6.6.64, or 6.11.11 depending on your current branch
  4. Install the updated kernel package using your distribution's package manager (e.g., `apt-get update && apt-get install linux-image-<version>` for Debian/Ubuntu, or `yum update kernel` for RHEL/CentOS)
  5. Reboot the system to load the patched kernel
  6. Verify the new kernel version is running with `uname -r` and confirm it is at or above the fixed release for your branch
  7. If using KFENCE for debugging, test reading from /proc/kcore to confirm the fix is effective (e.g., `dd if=/proc/kcore of=/dev/null bs=1M count=1` should no longer trigger KFENCE errors)
Caveat Kernel upgrade requires system reboot and may require rebuilding out-of-tree kernel modules; ensure compatibility of critical software with the new kernel version before production deployment

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 $3,200. 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-2024-56678 in production — separate from our analysis above.

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What this is

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