CVE-2026-64512

ACPI: CPPC: Suppress UBSAN warning caused by field misuse

State: Published
Severity: Not scored
Published: Jul 25, 2026
Updated: Aug 17, 2026
Reserved: Jul 19, 2026

Description

In the Linux kernel, the following vulnerability has been resolved:

ACPI: CPPC: Suppress UBSAN warning caused by field misuse

The definition of reg->access_width changes depending on the reg->space_id type. Type ACPI_ADR_SPACE_PLATFORM_COMM uses access_width to indicate the PCC region, which can result in a UBSAN if the value is greater than 4.

For example:

UBSAN: shift-out-of-bounds in drivers/acpi/cppc_acpi.c:1090:9 shift exponent 32 is too large for 32-bit type 'int' CPU: 61 UID: 0 PID: 1220 Comm: (udev-worker) Not tainted 7.0.10-201.fc44.aarch64 #1 PREEMPT(lazy) Hardware name: To be filled by O.E.M. Call trace: ...(trimming) ubsan_epilogue+0x10/0x48 __ubsan_handle_shift_out_of_bounds+0xdc/0x1e0 cpc_write+0x4d0/0x670 cppc_set_perf+0x18c/0x490 cppc_cpufreq_cpu_init+0x1c8/0x380 [cppc_cpufreq] ... (trimming)

Lets fix this by validating the region type, as well as whether access_width has a value. Then since we are returning bit_width directly for ACPI_ADR_SPACE_PLATFORM_COMM, drop the code correcting the size.

Scores

The record has no CVSS score.

Weaknesses

The record names no weakness.

Affected Products

Product	Versions
LinuxLinux	4949affd5288b867cdf115f5b08d6166b2027f87 to before b54c4632946ae42f2b39ed38abd909bbf78cbcc2Affected 01fc53be672acae37e611c80cc0b4f3939584de3 to before e904596ba6dd108534ffa15e3e46b2fe245145e2Affected 1b890ae474d19800a6be1696df7fb4d9a41676e4 to before 2fb80e962029000959f651665baa4838cc92eb99Affected 2f4a4d63a193be6fd530d180bb13c3592052904c to before 37f28bf8f14672dfa395994e41fd778a63f0bf5cAffected 2f4a4d63a193be6fd530d180bb13c3592052904c to before f29dc6132d4968e39d8fa575d1a12e2c718ce57bAffected 2f4a4d63a193be6fd530d180bb13c3592052904c to before dc066bd13c860bb27d6ace511210e18b8064c1d9Affected 2f4a4d63a193be6fd530d180bb13c3592052904c to before 1b1acf2dada0cc3931bb2cb9ff8832edfbee46a1Affected 6cb6b12b78dcd8867a3fdbb1b6d0ed1df2b208d1Affected 5.15.154 to before 5.15.155Affected 6.1.90 to before 6.1.178Affected 6.6.30 to before 6.6.145Affected 6.8.9 to before 6.9Affected
LinuxLinux	6.9Affected before 6.9Not affected 5.15.155 through 5.15.Not affected 6.1.178 through 6.1.Not affected 6.6.145 through 6.6.Not affected 6.12.96 through 6.12.Not affected 6.18.39 through 6.18.Not affected 7.1.4 through 7.1.Not affected 7.2 and laterNot affected

Product

Versions

LinuxLinux

4949affd5288b867cdf115f5b08d6166b2027f87 to before b54c4632946ae42f2b39ed38abd909bbf78cbcc2Affected
01fc53be672acae37e611c80cc0b4f3939584de3 to before e904596ba6dd108534ffa15e3e46b2fe245145e2Affected
1b890ae474d19800a6be1696df7fb4d9a41676e4 to before 2fb80e962029000959f651665baa4838cc92eb99Affected
2f4a4d63a193be6fd530d180bb13c3592052904c to before 37f28bf8f14672dfa395994e41fd778a63f0bf5cAffected
2f4a4d63a193be6fd530d180bb13c3592052904c to before f29dc6132d4968e39d8fa575d1a12e2c718ce57bAffected
2f4a4d63a193be6fd530d180bb13c3592052904c to before dc066bd13c860bb27d6ace511210e18b8064c1d9Affected
2f4a4d63a193be6fd530d180bb13c3592052904c to before 1b1acf2dada0cc3931bb2cb9ff8832edfbee46a1Affected
6cb6b12b78dcd8867a3fdbb1b6d0ed1df2b208d1Affected
5.15.154 to before 5.15.155Affected
6.1.90 to before 6.1.178Affected
6.6.30 to before 6.6.145Affected
6.8.9 to before 6.9Affected

LinuxLinux

6.9Affected
before 6.9Not affected
5.15.155 through 5.15.*Not affected
6.1.178 through 6.1.*Not affected
6.6.145 through 6.6.*Not affected
6.12.96 through 6.12.*Not affected
6.18.39 through 6.18.*Not affected
7.1.4 through 7.1.*Not affected
7.2 and laterNot affected

References

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