Vulnerability
Microarchitectural Data Sampling
Loads that fault or need microcode assistance pick up stale data from the processor's internal buffers and pass it to later speculative instructions.
- Also known as
- MDS, ZombieLoad, RIDL, Fallout
- Kind
- Data sampling
- CVEs
- 4
- Published
- 2019
- Linux reports it in
mds
Intel processors move data through small buffers between the core
and the caches: the store buffer, the fill buffers that hold lines
coming from memory, and the load ports. A load that faults or needs
a microcode assist can, while it waits, receive whatever one of
these buffers holds, from another program or from the kernel, and
pass it on speculatively. The attacker cannot choose what it
samples, only keep sampling. Intel assigned a CVE to each buffer;
the mitigation is the same for all of them, and Linux reports them
together in its mds file.
CVEs
| CVE | Name | Vendors | Published |
|---|---|---|---|
| CVE-2018-12126 | Microarchitectural Store Buffer Data Sampling (MSBDS, Fallout) | Intel | 2019-05-30 |
| CVE-2018-12127 | Microarchitectural Load Port Data Sampling (MLPDS, RIDL) | Intel | 2019-05-30 |
| CVE-2018-12130 | Microarchitectural Fill Buffer Data Sampling (MFBDS, ZombieLoad, RIDL) | Intel | 2019-05-30 |
| CVE-2019-11091 | Microarchitectural Data Sampling Uncacheable Memory (MDSUM, RIDL) | Intel | 2019-05-30 |
What the vendors say
- AMD: AMD states that its processors are not affected by MDS, based on its analysis and discussions with the researchers. Source.
How to check a machine
On Linux, /sys/devices/system/cpu/vulnerabilities/mds reports it; the kernel’s documentation lists the lines it can hold.