CVE-2024-40974

CVE-2024-40974 is a high-severity vulnerability in Linux Linux Kernel with a CVSS 3.x base score of 7.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-787.

Key facts

Description

In the Linux kernel, the following vulnerability has been resolved: powerpc/pseries: Enforce hcall result buffer validity and size plpar_hcall(), plpar_hcall9(), and related functions expect callers to provide valid result buffers of certain minimum size. Currently this is communicated only through comments in the code and the compiler has no idea. For example, if I write a bug like this: long retbuf[PLPAR_HCALL_BUFSIZE]; // should be PLPAR_HCALL9_BUFSIZE plpar_hcall9(H_ALLOCATE_VAS_WINDOW, retbuf, ...); This compiles with no diagnostics emitted, but likely results in stack corruption at runtime when plpar_hcall9() stores results past the end of the array. (To be clear this is a contrived example and I have not found a real instance yet.) To make this class of error less likely, we can use explicitly-sized array parameters instead of pointers in the declarations for the hcall APIs. When compiled with -Warray-bounds[1], the code above now provokes a diagnostic like this: error: array argument is too small; is of size 32, callee requires at least 72 [-Werror,-Warray-bounds] 60 | plpar_hcall9(H_ALLOCATE_VAS_WINDOW, retbuf, | ^ ~~~~~~ [1] Enabled for LLVM builds but not GCC for now. See commit 0da6e5fd6c37 ("gcc: disable '-Warray-bounds' for gcc-13 too") and related changes.

Frequently asked questions

What is CVE-2024-40974?
In the Linux kernel, the following vulnerability has been resolved: powerpc/pseries: Enforce hcall result buffer validity and size plpar_hcall(), plpar_hcall9(), and related functions expect callers to provide valid result buffers of certain minimum size. Currently this is communicated only through comments in the code and the compiler has no idea. For example, if I write a bug like this: long retbuf[PLPAR_HCALL_BUFSIZE]; // should be PLPAR_HCALL9_BUFSIZE plpar_hcall9(H_ALLOCATE_VAS_WINDOW, retbuf, ...); This compiles with no diagnostics emitted, but likely results in stack corruption at runtime when plpar_hcall9() stores results past the end of the array. (To be clear this is a contrived example and I have not found a real instance yet.) To make this class of error less likely, we can use explicitly-sized array parameters instead of pointers in the declarations for the hcall APIs. When compiled with -Warray-bounds[1], the code above now provokes a diagnostic like this: error: array argument is too small; is of size 32, callee requires at least 72 [-Werror,-Warray-bounds] 60 | plpar_hcall9(H_ALLOCATE_VAS_WINDOW, retbuf, | ^ ~~~~~~ [1] Enabled for LLVM builds but not GCC for now. See commit 0da6e5fd6c37 ("gcc: disable '-Warray-bounds' for gcc-13 too") and related changes.
How severe is CVE-2024-40974?
CVE-2024-40974 has a CVSS 3.x base score of 7.8, rated high severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2024-40974 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (22nd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2024-40974?
CVE-2024-40974 affects Linux Linux Kernel. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2024-40974?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2024-40974 have an EU (EUVD) identifier?
Yes. CVE-2024-40974 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2024-38771.
When was CVE-2024-40974 published?
CVE-2024-40974 was published on 2024-07-12 and last updated on 2026-06-17.

References

Affected products (1)

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