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authorPawan Gupta <pawan.kumar.gupta@linux.intel.com>2024-01-23 19:55:21 -0800
committerDave Hansen <dave.hansen@linux.intel.com>2024-10-21 15:05:43 -0700
commit3267cb6d3a174ff83d6287dcd5b0047bbd912452 (patch)
tree3012a2225e382fbad6c7bfe628288acde710f9d8 /arch
parentffd95846c6ec6cf1f93da411ea10d504036cab42 (diff)
x86/lam: Disable ADDRESS_MASKING in most cases
Linear Address Masking (LAM) has a weakness related to transient execution as described in the SLAM paper[1]. Unless Linear Address Space Separation (LASS) is enabled this weakness may be exploitable. Until kernel adds support for LASS[2], only allow LAM for COMPILE_TEST, or when speculation mitigations have been disabled at compile time, otherwise keep LAM disabled. There are no processors in market that support LAM yet, so currently nobody is affected by this issue. [1] SLAM: https://download.vusec.net/papers/slam_sp24.pdf [2] LASS: https://lore.kernel.org/lkml/20230609183632.48706-1-alexander.shishkin@linux.intel.com/ [ dhansen: update SPECULATION_MITIGATIONS -> CPU_MITIGATIONS ] Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Reviewed-by: Sohil Mehta <sohil.mehta@intel.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc:stable@vger.kernel.org Link: https://lore.kernel.org/all/5373262886f2783f054256babdf5a98545dc986b.1706068222.git.pawan.kumar.gupta%40linux.intel.com
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/Kconfig1
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 2852fcd82cbd..16354dfa6d96 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -2257,6 +2257,7 @@ config RANDOMIZE_MEMORY_PHYSICAL_PADDING
config ADDRESS_MASKING
bool "Linear Address Masking support"
depends on X86_64
+ depends on COMPILE_TEST || !CPU_MITIGATIONS # wait for LASS
help
Linear Address Masking (LAM) modifies the checking that is applied
to 64-bit linear addresses, allowing software to use of the