From 96c06cda5b4bdc6a3a9a8f8adc46c86077a70ee0 Mon Sep 17 00:00:00 2001 From: speck for Pawan Gupta Date: Mon, 6 May 2019 12:23:50 -0700 Subject: x86/mds: Add MDSUM variant to the MDS documentation 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 Signed-off-by: Thomas Gleixner Reviewed-by: Tyler Hicks Reviewed-by: Jon Masters [bwh: Backported to 4.9: adjust filename] Signed-off-by: Ben Hutchings Signed-off-by: Greg Kroah-Hartman --- Documentation/hw-vuln/mds.rst | 5 +++-- Documentation/x86/mds.rst | 5 +++++ 2 files changed, 8 insertions(+), 2 deletions(-) (limited to 'Documentation') diff --git a/Documentation/hw-vuln/mds.rst b/Documentation/hw-vuln/mds.rst index aec9e49256b5..5e92eca5c0a7 100644 --- 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 ------- diff --git a/Documentation/x86/mds.rst b/Documentation/x86/mds.rst index 3d6f943f1afb..979945be257a 100644 --- a/Documentation/x86/mds.rst +++ b/Documentation/x86/mds.rst @@ -12,6 +12,7 @@ on internal buffers in Intel CPUs. The variants are: - 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 certain conditions, which again can be 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 -------------------- -- cgit v1.2.3