x86: Fix jump label with RO/NX module protection crash

If we use jump table in module init, there are marked
as removed in __jump_table section after init is done.

But we already applied ro permissions on the module, so
we can't modify a read only section (crash in
remove_jump_label_module_init).

Make the __jump_table section rw.

Signed-off-by: Matthieu CASTET <castet.matthieu@free.fr>
Cc: Xiaotian Feng <xtfeng@gmail.com>
Cc: Jason Baron <jbaron@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Siarhei Liakh <sliakh.lkml@gmail.com>
Cc: Xuxian Jiang <jiang@cs.ncsu.edu>
Cc: James Morris <jmorris@namei.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Dave Jones <davej@redhat.com>
Cc: Kees Cook <kees.cook@canonical.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
LKML-Reference: <4D3C3F20.7030203@free.fr>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/arch/x86/include/asm/jump_label.h b/arch/x86/include/asm/jump_label.h
index f52d42e805853ea09532a86aca6290410bb2d83b..574dbc22893a9301914def19c5004b9ec1b851fe 100644 (file)
--- a/arch/x86/include/asm/jump_label.h
+++ b/arch/x86/include/asm/jump_label.h
@@ -14,7 +14,7 @@
        do {                                                    \
                asm goto("1:"                                   \
                        JUMP_LABEL_INITIAL_NOP                  \
-                       ".pushsection __jump_table,  \"a\" \n\t"\
+                       ".pushsection __jump_table,  \"aw\" \n\t"\
                        _ASM_PTR "1b, %l[" #label "], %c0 \n\t" \
                        ".popsection \n\t"                      \
                        : :  "i" (key) :  : label);             \