From 99190ec061fb0863b4e0e245e5d8a807f938818c Mon Sep 17 00:00:00 2001 From: Andy Lutomirski Date: Thu, 29 Jun 2017 08:53:19 -0700 Subject: [PATCH] x86/mm: Disable PCID on 32-bit kernels commit cba4671af7550e008f7a7835f06df0763825bf3e upstream. 32-bit kernels on new hardware will see PCID in CPUID, but PCID can only be used in 64-bit mode. Rather than making all PCID code conditional, just disable the feature on 32-bit builds. Signed-off-by: Andy Lutomirski Reviewed-by: Nadav Amit Reviewed-by: Borislav Petkov Reviewed-by: Thomas Gleixner Cc: Andrew Morton Cc: Arjan van de Ven Cc: Borislav Petkov Cc: Dave Hansen Cc: Linus Torvalds Cc: Mel Gorman Cc: Peter Zijlstra Cc: Rik van Riel Cc: linux-mm@kvack.org Link: http://lkml.kernel.org/r/2e391769192a4d31b808410c383c6bf0734bc6ea.1498751203.git.luto@kernel.org Signed-off-by: Ingo Molnar Cc: Hugh Dickins Signed-off-by: Greg Kroah-Hartman (cherry picked from commit 78043e5b6fb2921d836b31f23e89e52925191153) Orabug: 27333760 CVE: CVE-2017-5754 Signed-off-by: Pavel Tatashin Signed-off-by: Kirtikar Kashyap --- arch/x86/include/asm/disabled-features.h | 4 +++- arch/x86/kernel/cpu/bugs.c | 8 ++++++++ 2 files changed, 11 insertions(+), 1 deletion(-) diff --git a/arch/x86/include/asm/disabled-features.h b/arch/x86/include/asm/disabled-features.h index f226df064660..8b17c2ad1048 100644 --- a/arch/x86/include/asm/disabled-features.h +++ b/arch/x86/include/asm/disabled-features.h @@ -21,11 +21,13 @@ # define DISABLE_K6_MTRR (1<<(X86_FEATURE_K6_MTRR & 31)) # define DISABLE_CYRIX_ARR (1<<(X86_FEATURE_CYRIX_ARR & 31)) # define DISABLE_CENTAUR_MCR (1<<(X86_FEATURE_CENTAUR_MCR & 31)) +# define DISABLE_PCID 0 #else # define DISABLE_VME 0 # define DISABLE_K6_MTRR 0 # define DISABLE_CYRIX_ARR 0 # define DISABLE_CENTAUR_MCR 0 +# define DISABLE_PCID (1<<(X86_FEATURE_PCID & 31)) #endif /* CONFIG_X86_64 */ /* @@ -35,7 +37,7 @@ #define DISABLED_MASK1 0 #define DISABLED_MASK2 0 #define DISABLED_MASK3 (DISABLE_CYRIX_ARR|DISABLE_CENTAUR_MCR|DISABLE_K6_MTRR) -#define DISABLED_MASK4 0 +#define DISABLED_MASK4 (DISABLE_PCID) #define DISABLED_MASK5 0 #define DISABLED_MASK6 0 #define DISABLED_MASK7 0 diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c index 03445346ee0a..4c7dd836304a 100644 --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -65,6 +65,14 @@ static void __init check_fpu(void) void __init check_bugs(void) { +#ifdef CONFIG_X86_32 + /* + * Regardless of whether PCID is enumerated, the SDM says + * that it can't be enabled in 32-bit mode. + */ + setup_clear_cpu_cap(X86_FEATURE_PCID); +#endif + identify_boot_cpu(); #ifndef CONFIG_SMP pr_info("CPU: "); -- 2.50.1