From: speck for Pawan Gupta speck@linutronix.de
commit e672f8bf71c66253197e503f75c771dd28ada4a0 upstream.
Updated the documentation for a new CVE-2019-11091 Microarchitectural Data Sampling Uncacheable Memory (MDSUM) which is a variant of Microarchitectural Data Sampling (MDS). MDS is a family of side channel attacks on internal buffers in Intel CPUs.
MDSUM is a special case of MSBDS, MFBDS and MLPDS. An uncacheable load from memory that takes a fault or assist can leave data in a microarchitectural structure that may later be observed using one of the same methods used by MSBDS, MFBDS or MLPDS. There are no new code changes expected for MDSUM. The existing mitigation for MDS applies to MDSUM as well.
Signed-off-by: Pawan Gupta pawan.kumar.gupta@linux.intel.com Signed-off-by: Thomas Gleixner tglx@linutronix.de Reviewed-by: Tyler Hicks tyhicks@canonical.com Reviewed-by: Jon Masters jcm@redhat.com [bwh: Backported to 4.4: adjust filename] Signed-off-by: Ben Hutchings ben@decadent.org.uk Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- Documentation/hw-vuln/mds.rst | 5 +++-- Documentation/x86/mds.rst | 5 +++++ 2 files changed, 8 insertions(+), 2 deletions(-)
--- a/Documentation/hw-vuln/mds.rst +++ b/Documentation/hw-vuln/mds.rst @@ -32,11 +32,12 @@ Related CVEs
The following CVE entries are related to the MDS vulnerability:
- ============== ===== ============================================== + ============== ===== =================================================== CVE-2018-12126 MSBDS Microarchitectural Store Buffer Data Sampling CVE-2018-12130 MFBDS Microarchitectural Fill Buffer Data Sampling CVE-2018-12127 MLPDS Microarchitectural Load Port Data Sampling - ============== ===== ============================================== + CVE-2019-11091 MDSUM Microarchitectural Data Sampling Uncacheable Memory + ============== ===== ===================================================
Problem ------- --- a/Documentation/x86/mds.rst +++ b/Documentation/x86/mds.rst @@ -12,6 +12,7 @@ on internal buffers in Intel CPUs. The v - Microarchitectural Store Buffer Data Sampling (MSBDS) (CVE-2018-12126) - Microarchitectural Fill Buffer Data Sampling (MFBDS) (CVE-2018-12130) - Microarchitectural Load Port Data Sampling (MLPDS) (CVE-2018-12127) + - Microarchitectural Data Sampling Uncacheable Memory (MDSUM) (CVE-2019-11091)
MSBDS leaks Store Buffer Entries which can be speculatively forwarded to a dependent load (store-to-load forwarding) as an optimization. The forward @@ -38,6 +39,10 @@ faulting or assisting loads under certai exploited eventually. Load ports are shared between Hyper-Threads so cross thread leakage is possible.
+MDSUM is a special case of MSBDS, MFBDS and MLPDS. An uncacheable load from +memory that takes a fault or assist can leave data in a microarchitectural +structure that may later be observed using one of the same methods used by +MSBDS, MFBDS or MLPDS.
Exposure assumptions --------------------