Processor vulnerability
CVE-2018-12130
A load that faults or needs a microcode assist picks up stale data from the fill buffers, left there by other code, and leaks it through the cache.
- Name
- Microarchitectural Fill Buffer Data Sampling
- Also known as
- MFBDS, ZombieLoad, RIDL
- Vulnerability
- Microarchitectural Data Sampling
- Kind
- Data sampling
- CVE published
- 2019-05-30 CVE record
- Advisories
- INTEL-SA-00233
- Linux reports it in
mds
This variant of MDS samples the fill buffers, which hold cache lines on their way between memory and the L1 cache. A load that faults or needs a microcode assist can receive data that is still in it from code that ran before, on the same thread or, with SMT, on the sibling thread, and pass it to later instructions that leave a trace in the cache.
Linux reports all variants in one file; on Silvermont, Airmont and Xeon Phi processors it reports only the store buffer variant.
Affected processors
14 of the 57 microarchitectures listed are affected in all or some of their models.
| Microarchitecture | Status | Detail | Source |
|---|---|---|---|
| NetBurst (Prescott, Nocona) | Affected | Linux 7.3 sets the bug on INTEL_P4_CEDARMILL, INTEL_P4_PRESCOTT, INTEL_P4_PRESCOTT_2M: cpu_vuln_whitelist does not list them with NO_SPECULATION or NO_MDS or MSBDS_ONLY; and a processor released before 2018 does not report MDS_NO | Linux 7.3 |
| Core (Merom, Conroe) | Affected | Linux 7.3 sets the bug on INTEL_CORE2_MEROM, INTEL_CORE2_MEROM_L: cpu_vuln_whitelist does not list them with NO_SPECULATION or NO_MDS or MSBDS_ONLY; and a processor released before 2018 does not report MDS_NO | Linux 7.3 |
| Penryn | Affected | Linux 7.3 sets the bug on INTEL_CORE2_DUNNINGTON, INTEL_CORE2_PENRYN: cpu_vuln_whitelist does not list them with NO_SPECULATION or NO_MDS or MSBDS_ONLY; and a processor released before 2018 does not report MDS_NO | Linux 7.3 |
| Nehalem | Affected | Linux 7.3 sets the bug on INTEL_NEHALEM, INTEL_NEHALEM_EP, INTEL_NEHALEM_EX, INTEL_NEHALEM_G: cpu_vuln_whitelist does not list them with NO_SPECULATION or NO_MDS or MSBDS_ONLY; and a processor released before 2018 does not report MDS_NO | Linux 7.3 |
| Westmere | Affected | Linux 7.3 sets the bug on INTEL_WESTMERE, INTEL_WESTMERE_EP, INTEL_WESTMERE_EX: cpu_vuln_whitelist does not list them with NO_SPECULATION or NO_MDS or MSBDS_ONLY; and a processor released before 2018 does not report MDS_NO | Linux 7.3 |
| Sandy Bridge | Affected | Linux 7.3 sets the bug on INTEL_SANDYBRIDGE, INTEL_SANDYBRIDGE_X: cpu_vuln_whitelist does not list them with NO_SPECULATION or NO_MDS or MSBDS_ONLY; and a processor released before 2018 does not report MDS_NO | Linux 7.3 |
| Ivy Bridge | Affected | Linux 7.3 sets the bug on INTEL_IVYBRIDGE, INTEL_IVYBRIDGE_X: cpu_vuln_whitelist does not list them with NO_SPECULATION or NO_MDS or MSBDS_ONLY; and a processor released before 2018 does not report MDS_NO | Linux 7.3 |
| 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 |
| 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 |
| Kaby Lake | Some models | 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): Not Affected 06_9EH stepping 9 (1. Kaby Lake S - 2. Kaby Lake Xeon E3): MCU+Software | Intel’s list |
| Coffee Lake | Some models | 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): Not Affected 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): Not Affected | Intel’s list |
| Airmont | Some models | Linux 7.3 sets the bug on INTEL_ATOM_AIRMONT, INTEL_ATOM_AIRMONT_NP: cpu_vuln_whitelist does not list them with NO_SPECULATION or NO_MDS or MSBDS_ONLY; and a processor released before 2018 does not report MDS_NO | Linux 7.3 |
| Comet Lake | Not affected | 06_8EH stepping C (1. Whiskey Lake V - 2. Comet Lake U42 - 3. Amber Lake Y): Not Affected 06_A5H stepping 2 (Comet Lake H): Not Affected 06_A5H stepping 3 (Comet Lake-S): Not Affected 06_A5H stepping 5 (Comet Lake-S): Not Affected 06_A6H stepping 0 (Comet Lake U62): Not Affected 06_A6H stepping 1 (Comet Lake U62): Not Affected | Intel’s list |
| Ice Lake (client) | Not affected | 06_7EH stepping 5 (Ice Lake U - Ice Lake Y): Not Affected | Intel’s list |
| Tiger Lake | Not affected | 06_8CH stepping 1 (Tiger Lake U): Not Affected 06_8CH stepping 1 (Tiger Lake U): Not Affected 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): Not Affected | 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 |
| Rocket Lake | Not affected | 06_A7H stepping 1 (Rocket Lake): 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 |
| Cooper Lake | Not affected | 06_55H stepping B (Cooper Lake): Not Affected | Intel’s list |
| Ice Lake (server) | Not affected | 06_6AH stepping 6 (Ice Lake Xeon-SP): Not Affected 06_6CH stepping All (Ice Lake Xeon D (Idaville)): 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 |
| Bonnell | Not affected | Linux 7.3 lists INTEL_ATOM_BONNELL, INTEL_ATOM_BONNELL_MID in cpu_vuln_whitelist with NO_SPECULATION | Linux 7.3 |
| Saltwell | Not affected | Linux 7.3 lists INTEL_ATOM_SALTWELL, INTEL_ATOM_SALTWELL_MID, INTEL_ATOM_SALTWELL_TABLET in cpu_vuln_whitelist with NO_SPECULATION | Linux 7.3 |
| Silvermont | Not affected | Linux 7.3 lists INTEL_ATOM_SILVERMONT, INTEL_ATOM_SILVERMONT_D, INTEL_ATOM_SILVERMONT_MID, INTEL_ATOM_SILVERMONT_MID2 in cpu_vuln_whitelist with MSBDS_ONLY | Linux 7.3 |
| 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 |
| Tremont | Not affected | 06_86H stepping 5 (Snow Ridge BTS (Tremont)): Not Affected 06_86H stepping 7 (Parker Ridge / Snow Ridge NS/NX/BTS): Not Affected 06_96H stepping All (Elkhart Lake (Tremont)): Not Affected 06_9CH stepping All (Jasper Lake (Tremont)): 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 |
| Knights Landing | Not affected | Linux 7.3 lists INTEL_XEON_PHI_KNL in cpu_vuln_whitelist with MSBDS_ONLY | Linux 7.3 |
| Knights Mill | Not affected | Linux 7.3 lists INTEL_XEON_PHI_KNM in cpu_vuln_whitelist with MSBDS_ONLY | Linux 7.3 |
| K8 (Hammer) | Not affected | Linux 7.3 lists AMD family Fh in cpu_vuln_whitelist with NO_MDS | Linux 7.3 |
| K10 (Family 10h) | Not affected | Linux 7.3 lists AMD family 10h, AMD family 12h in cpu_vuln_whitelist with NO_MDS | Linux 7.3 |
| Bulldozer | Not affected | Linux 7.3 lists AMD family 15h in cpu_vuln_whitelist with NO_MDS | Linux 7.3 |
| Piledriver | Not affected | Linux 7.3 lists AMD family 15h in cpu_vuln_whitelist with NO_MDS | Linux 7.3 |
| Steamroller | Not affected | Linux 7.3 lists AMD family 15h in cpu_vuln_whitelist with NO_MDS | Linux 7.3 |
| Excavator | Not affected | Linux 7.3 lists AMD family 15h in cpu_vuln_whitelist with NO_MDS | Linux 7.3 |
| Zen | Not affected | Linux 7.3 lists AMD family 17h in cpu_vuln_whitelist with NO_MDS | Linux 7.3 |
| Zen+ | Not affected | Linux 7.3 lists AMD family 17h in cpu_vuln_whitelist with NO_MDS | Linux 7.3 |
| Zen 2 | Not affected | Linux 7.3 lists AMD family 17h in cpu_vuln_whitelist with NO_MDS | Linux 7.3 |
| Zen 3 | Not affected | Linux 7.3 lists AMD family 19h in cpu_vuln_whitelist with NO_MDS | Linux 7.3 |
| Zen 4 | Not affected | Linux 7.3 lists AMD family 19h in cpu_vuln_whitelist with NO_MDS | Linux 7.3 |
| Zen 5 | Not affected | Linux 7.3 lists AMD family 1Ah in cpu_vuln_whitelist with NO_MDS | Linux 7.3 |
| Zen 6 | Not affected | Linux 7.3 lists AMD family 1Ah in cpu_vuln_whitelist with NO_MDS | Linux 7.3 |
| Bobcat | Not affected | Linux 7.3 lists AMD family 14h in cpu_vuln_whitelist with NO_MDS | Linux 7.3 |
| Jaguar | Not affected | Linux 7.3 lists AMD family 16h in cpu_vuln_whitelist with NO_MDS | Linux 7.3 |
| Puma | Not affected | Linux 7.3 lists AMD family 16h in cpu_vuln_whitelist with NO_MDS | Linux 7.3 |
| Dhyana | Not affected | Linux 7.3 lists Hygon family 18h in cpu_vuln_whitelist with NO_MDS | Linux 7.3 |
Mitigations
- Kernel: Microcode makes the old VERW instruction clear the processor's internal buffers; Linux executes it before returning to user space and before entering a guest. On processors with SMT the sibling thread is not protected unless SMT is off. Instructions: VERW. Source.
How to check a machine
On Linux, /sys/devices/system/cpu/vulnerabilities/mds holds one of these lines:
Not affectedVulnerableMitigation: Clear CPU buffersVulnerable: Clear CPU buffers attempted, no microcode
On an affected processor the line ends with the SMT state, such as SMT vulnerable or SMT disabled. Source.
Related CVEs
- CVE-2018-12126 Microarchitectural Store Buffer Data Sampling
- CVE-2018-12127 Microarchitectural Load Port Data Sampling
- CVE-2019-11091 Microarchitectural Data Sampling Uncacheable Memory