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authorH. Peter Anvin <hpa@linux.intel.com>2014-02-13 07:46:04 -0800
committerH. Peter Anvin <hpa@linux.intel.com>2014-02-13 08:40:52 -0800
commit4640c7ee9b8953237d05a61ea3ea93981d1bc961 (patch)
tree580aa78183348a9cfcea51a50b1cc4e8ef5a309f /arch
parent03bbd596ac04fef47ce93a730b8f086d797c3021 (diff)
downloadlinux-stericsson-4640c7ee9b8953237d05a61ea3ea93981d1bc961.tar.gz
x86, smap: smap_violation() is bogus if CONFIG_X86_SMAP is off
If CONFIG_X86_SMAP is disabled, smap_violation() tests for conditions which are incorrect (as the AC flag doesn't matter), causing spurious faults. The dynamic disabling of SMAP (nosmap on the command line) is fine because it disables X86_FEATURE_SMAP, therefore causing the static_cpu_has() to return false. Found by Fengguang Wu's test system. [ v3: move all predicates into smap_violation() ] [ v2: use IS_ENABLED() instead of #ifdef ] Reported-by: Fengguang Wu <fengguang.wu@intel.com> Link: http://lkml.kernel.org/r/20140213124550.GA30497@localhost Signed-off-by: H. Peter Anvin <hpa@linux.intel.com> Cc: <stable@vger.kernel.org> # v3.7+
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/mm/fault.c14
1 files changed, 9 insertions, 5 deletions
diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index 9d591c895803..6dea040cc3a1 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -1001,6 +1001,12 @@ static int fault_in_kernel_space(unsigned long address)
static inline bool smap_violation(int error_code, struct pt_regs *regs)
{
+ if (!IS_ENABLED(CONFIG_X86_SMAP))
+ return false;
+
+ if (!static_cpu_has(X86_FEATURE_SMAP))
+ return false;
+
if (error_code & PF_USER)
return false;
@@ -1087,11 +1093,9 @@ __do_page_fault(struct pt_regs *regs, unsigned long error_code)
if (unlikely(error_code & PF_RSVD))
pgtable_bad(regs, error_code, address);
- if (static_cpu_has(X86_FEATURE_SMAP)) {
- if (unlikely(smap_violation(error_code, regs))) {
- bad_area_nosemaphore(regs, error_code, address);
- return;
- }
+ if (unlikely(smap_violation(error_code, regs))) {
+ bad_area_nosemaphore(regs, error_code, address);
+ return;
}
/*