Processor vulnerability
CVE-2022-21166
A write smaller than a device register can copy extra bytes of stale data from the writing core's fill buffers into the register.
- Name
- Device Register Partial Write
- Also known as
- DRPW
- Vulnerability
- Processor MMIO Stale Data
- Kind
- Data sampling
- CVE published
- 2022-06-15 CVE record
- Advisories
- INTEL-SA-00615
- Linux reports it in
mmio_stale_data
Some device registers mishandle writes narrower than themselves:
instead of taking only the bytes written, they take more, filled
from the fill buffers of the core that wrote. Stale data from that
core can so end up in a register that another party, such as the
guest that owns the device, can read.What the sources say of each microarchitecture. Intel’s list gives each CPUID family, model and stepping it covers, with Intel’s mitigation for it (Software, MCU for a microcode update, or Hardware).
Affected processors
14 of the 28 microarchitectures listed are affected in all or some of their models.
| Microarchitecture | Status | Detail | Source |
|---|---|---|---|
| Haswell | Affected | 06_3FH stepping 2 (Haswell Server EP/EP4S): MCU+Software 06_3FH stepping 4 (Haswell Server EX): MCU+Software | Intel’s list |
| Broadwell | Affected | 06_4FH stepping 1 (1. Broadwell Server E/EP/EP4S - 2. Broadwell Server EX): MCU+Software 06_56H stepping 3 (Broadwell DE V2 - V3): MCU+Software 06_56H stepping 4 (Broadwell DE Y0): MCU+Software 06_56H stepping 5 (Hewitt Lake (Broadwell DE)): MCU+Software | Intel’s list |
| Skylake | Affected | 06_5EH stepping 3 (1. Skylake Xeon E3 - 2. Skylake H - 3. Skylake S): MCU+Software | Intel’s list |
| Kaby Lake | Affected | 06_8EH stepping 9 (1. Amber Lake-Y - 2. Kaby Lake U - 3. Kaby Lake U23e - 4. Kaby Lake Y): MCU+Software 06_8EH stepping C (1. Whiskey Lake V - 2. Comet Lake U42 - 3. Amber Lake Y): MCU+Software 06_9EH stepping 9 (1. Kaby Lake S - 2. Kaby Lake Xeon E3): MCU+Software | Intel’s list |
| Coffee Lake | Affected | 06_8EH stepping A (1. Coffee Lake U43e - 2. Whiskey Lake): MCU+Software 06_8EH stepping B (Whiskey Lake U): MCU+Software 06_8EH stepping C (1. Whiskey Lake V - 2. Comet Lake U42 - 3. Amber Lake Y): MCU+Software 06_9EH stepping A (Coffee Lake H): MCU+Software 06_9EH stepping C (Coffee Lake S): MCU+Software 06_9EH stepping D (1. Coffee Lake H - 2. Coffee Lake Xeon E - 3. Coffee Lake S): MCU+Software | Intel’s list |
| Comet Lake | Affected | 06_8EH stepping C (1. Whiskey Lake V - 2. Comet Lake U42 - 3. Amber Lake Y): MCU+Software 06_A5H stepping 2 (Comet Lake H): MCU+Software 06_A5H stepping 3 (Comet Lake-S): MCU+Software 06_A5H stepping 5 (Comet Lake-S): MCU+Software 06_A6H stepping 0 (Comet Lake U62): MCU+Software 06_A6H stepping 1 (Comet Lake U62): MCU+Software | Intel’s list |
| Ice Lake (client) | Affected | 06_7EH stepping 5 (Ice Lake U - Ice Lake Y): MCU+Software | Intel’s list |
| Rocket Lake | Affected | 06_A7H stepping 1 (Rocket Lake): MCU+Software | Intel’s list |
| Skylake-SP | Affected | 06_55H stepping 3 (Skylake Server): MCU+Software 06_55H stepping 4 (1. Skylake Server - 2. Skylake D/Bakerville): MCU+Software | Intel’s list |
| Cascade Lake | Affected | Linux 7.3 lists INTEL_SKYLAKE_X steppings 5 to 7 in cpu_vuln_blacklist with MMIO | Linux 7.3 |
| Cooper Lake | Affected | 06_55H stepping B (Cooper Lake): MCU+Software | Intel’s list |
| Ice Lake (server) | Affected | 06_6AH stepping 6 (Ice Lake Xeon-SP): MCU+Software 06_6CH stepping All (Ice Lake Xeon D (Idaville)): MCU+Software | Intel’s list |
| Tremont | Affected | 06_86H stepping 5 (Snow Ridge BTS (Tremont)): MCU+Software 06_86H stepping 7 (Parker Ridge / Snow Ridge NS/NX/BTS): MCU+Software 06_96H stepping All (Elkhart Lake (Tremont)): MCU+Software 06_9CH stepping All (Jasper Lake (Tremont)): MCU+Software | Intel’s list |
| Tiger Lake | Some models | 06_8CH stepping 1 (Tiger Lake U): Not Affected 06_8CH stepping 1 (Tiger Lake U): MCU_BIOS+BIOS 06_8CH stepping 2 (1. Tiger Lake U Refresh - 2. Tiger Lake H35): Not Affected 06_8DH stepping 1 (Tiger Lake H): Not Affected 06_8DH stepping 1 (Tiger Lake H): MCU_BIOS+BIOS | Intel’s list |
| Alder Lake | Not affected | 06_97H stepping 2 (Alder Lake S (Golden Cove - Gracemont)): Not Affected 06_97H stepping 5 (Alder Lake S (Golden Cove - Gracemont)): Not Affected 06_97H stepping 5 (Catlow (Golden Cove)): Not Affected 06_9AH stepping 3 (1. Alder Lake H (Golden Cove - Gracemont) - 2. Alder Lake P (Golden Cove - Gracemont)): Not Affected 06_9AH stepping 4 (Alder Lake U (Golden Cove - Gracemont)): Not Affected | Intel’s list |
| Raptor Lake | Not affected | 06_B7H stepping 1 (1. Raptor Lake S - 2. Raptor Lake HX (Raptor Cove/Gracemont)): Not Affected 06_B7H stepping 1 (Catlow (Raptor Cove)): Not Affected 06_BAH stepping 2 - 3 - 8 (1. Raptor Lake P - 2. Raptor Lake H + refresh - 3. Raptor Lake U + refresh (Raptor Cove/Gracemont)): Not Affected 06_BFH stepping 2 - 5 (Raptor Lake S (Raptor Cove/Gracemont)): Not Affected | Intel’s list |
| Meteor Lake | Not affected | 06_AAH stepping 4 (Meteor Lake U/H/PS (Redwood Cove - Crestmont)): Not Affected | Intel’s list |
| Arrow Lake | Not affected | 06_B5H stepping 0 (Arrow Lake U (Redwood Cove - Crestmont)): Not Affected 06_C5H stepping 2 (Arrow Lake H (Lion Cove - Skymont)): Not Affected 06_C6H stepping 2 (Arrow Lake H/HX/S/S Plus (Lion Cove - Skymont)): Not Affected | Intel’s list |
| Lunar Lake | Not affected | 06_BDH stepping 1 (Lunar Lake (Lion Cove - Skymont)): Not Affected | Intel’s list |
| Panther Lake | Not affected | 06_CCH stepping 2 - 3 (Panther Lake (Cougar Cove - Darkmont)): Not Affected | Intel’s list |
| Emerald Rapids | Not affected | 06_CFH stepping 2 (Emerald Rapids (Raptor Cove)): Not Affected | Intel’s list |
| Sapphire Rapids | Not affected | 06_8FH stepping 5 - 6 - 7 - 8 (1. Sapphire Rapids - 2. Sapphire Rapids Edge Enhanced (Golden Cove)): Not Affected 06_8FH stepping 5 - 6 - 8 (Sapphire Rapids (Golden Cove) - Sapphire Rapids HBM): Not Affected | Intel’s list |
| Granite Rapids | Not affected | 06_ADH stepping 1 (Granite Rapids (Redwood Cove)): Not Affected 06_ADH stepping 1 (Granite Rapids (Redwood Cove)): Not Affected 06_ADH stepping 1 (Granite Rapids R1S (Redwood Cove)): Not Affected 06_AEH stepping 1 (Granite Rapids D (Redwood Cove)/Kaseyville): Not Affected | Intel’s list |
| Sierra Forest | Not affected | 06_AFH stepping 3 (Sierra Forest (Crestmont)): Not Affected | Intel’s list |
| Clearwater Forest | Not affected | 06_DDH stepping 1 (Clearwater Forest (Darkmont)): Not Affected | Intel’s list |
| Goldmont | Not affected | 06_5CH stepping A (Apollo Lake): Not Affected 06_5FH stepping All (Denverton (Goldmont)): Not Affected | Intel’s list |
| Goldmont Plus | Not affected | 06_7AH stepping 8 (Gemini Lake): Not Affected | Intel’s list |
| Gracemont | Not affected | 06_9AH stepping 4 (Arizona Beach (Gracemont)): Not Affected 06_BEH stepping 0 (Alder Lake N (Gracemont)/Twin Lake): Not Affected | Intel’s list |
Mitigations
- Kernel: With Intel's microcode, VERW also clears the buffers these flaws leave data in; Linux executes it on return to user space where the processor also has MDS or TAA, and before entering a guest that has access to devices. Instructions: VERW. Source.
How to check a machine
On Linux, /sys/devices/system/cpu/vulnerabilities/mmio_stale_data holds one of these lines:
Not affectedVulnerableVulnerable: Clear CPU buffers attempted, no microcodeMitigation: Clear CPU buffers
On an affected processor the line ends with the SMT state. Source.
Related CVEs
- CVE-2022-21123 Shared Buffers Data Read
- CVE-2022-21125 Shared Buffers Data Sampling