Change-Id: I7c9d49079d4e18390c2d520513a4afd55e6eaa3e

arch/x86/Kconfig

@@ -82,7 +82,8 @@ config X86
 	select CLKEVT_I8253
 	select ARCH_HAVE_NMI_SAFE_CMPXCHG
 	select GENERIC_IOMAP
-	select DCACHE_WORD_ACCESS
+	select DCACHE_WORD_ACCESS if !DEBUG_PAGEALLOC
+	select HAVE_ARCH_SECCOMP_FILTER
 
 config INSTRUCTION_DECODER
 	def_bool (KPROBES || PERF_EVENTS)

arch/x86/kernel/ptrace.c

@@ -1480,7 +1480,11 @@ long syscall_trace_enter(struct pt_regs *regs)
 		regs->flags |= X86_EFLAGS_TF;
 
 	/* do the secure computing check first */
-	secure_computing(regs->orig_ax);
+	if (secure_computing(regs->orig_ax)) {
+		/* seccomp failures shouldn't expose any additional code. */
+		ret = -1L;
+		goto out;
+	}
 
 	if (unlikely(test_thread_flag(TIF_SYSCALL_EMU)))
 		ret = -1L;
@@ -1505,6 +1509,7 @@ long syscall_trace_enter(struct pt_regs *regs)
 				    regs->dx, regs->r10);
 #endif
 
+out:
 	return ret ?: regs->orig_ax;
 }