4.9-stable review patch. If anyone has any objections, please let me know.
------------------ From: Thomas Gleixner <[email protected]> commit a89f040fa34ec9cd682aed98b8f04e3c47d998bd upstream. Many x86 CPUs leak information to user space due to missing isolation of user space and kernel space page tables. There are many well documented ways to exploit that. The upcoming software migitation of isolating the user and kernel space page tables needs a misfeature flag so code can be made runtime conditional. Add the BUG bits which indicates that the CPU is affected and add a feature bit which indicates that the software migitation is enabled. Assume for now that _ALL_ x86 CPUs are affected by this. Exceptions can be made later. Signed-off-by: Thomas Gleixner <[email protected]> Cc: Andy Lutomirski <[email protected]> Cc: Boris Ostrovsky <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: Brian Gerst <[email protected]> Cc: Dave Hansen <[email protected]> Cc: David Laight <[email protected]> Cc: Denys Vlasenko <[email protected]> Cc: Eduardo Valentin <[email protected]> Cc: Greg KH <[email protected]> Cc: H. Peter Anvin <[email protected]> Cc: Josh Poimboeuf <[email protected]> Cc: Juergen Gross <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Will Deacon <[email protected]> Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] Signed-off-by: Ingo Molnar <[email protected]> Signed-off-by: David Woodhouse <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- arch/x86/include/asm/cpufeatures.h | 1 + arch/x86/kernel/cpu/common.c | 4 ++++ 2 files changed, 5 insertions(+) --- a/arch/x86/include/asm/cpufeatures.h +++ b/arch/x86/include/asm/cpufeatures.h @@ -316,5 +316,6 @@ #define X86_BUG_SWAPGS_FENCE X86_BUG(11) /* SWAPGS without input dep on GS */ #define X86_BUG_MONITOR X86_BUG(12) /* IPI required to wake up remote CPU */ #define X86_BUG_AMD_E400 X86_BUG(13) /* CPU is among the affected by Erratum 400 */ +#define X86_BUG_CPU_INSECURE X86_BUG(14) /* CPU is insecure and needs kernel page table isolation */ #endif /* _ASM_X86_CPUFEATURES_H */ --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -882,6 +882,10 @@ static void __init early_identify_cpu(st } setup_force_cpu_cap(X86_FEATURE_ALWAYS); + + /* Assume for now that ALL x86 CPUs are insecure */ + setup_force_cpu_bug(X86_BUG_CPU_INSECURE); + fpu__init_system(c); }
