module: Clean up ro/nx after early module load failures

The commit

    4982223e51e8 module: set nx before marking module MODULE_STATE_COMING.

introduced a regression: if a module fails to parse its arguments or
if mod_sysfs_setup fails, then the module's memory will be freed
while still read-only.  Anything that reuses that memory will crash
as soon as it tries to write to it.

Cc: stable@vger.kernel.org # v3.16
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

1 files changed, 5 insertions, 0 deletions

diff --git a/kernel/module.c b/kernel/module.c
index 6f69463f0066..03214bd288e9 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -3304,6 +3304,11 @@ static int load_module(struct load_info *info, const char __user *uargs,
         mutex_lock(&module_mutex);
         module_bug_cleanup(mod);
         mutex_unlock(&module_mutex);
+
+        /* we can't deallocate the module until we clear memory protection */
+        unset_module_init_ro_nx(mod);
+        unset_module_core_ro_nx(mod);
+
  ddebug_cleanup:
         dynamic_debug_remove(info->debug);
         synchronize_sched();