From: "Luis R. Rodriguez" <mcg...@suse.com>

Commit f2411da746985 ("driver-core: add driver module
asynchronous probe support") added async probe support,
in two forms:

  * in-kernel driver specification annotation
  * generic async_probe module parameter (modprobe foo async_probe)

To support the generic kernel parameter parse_args() was
extended via commit ecc8617053e0 ("module: add extra
argument for parse_params() callback") however commit
failed to f2411da746985 failed to add the required argument.

This causes a crash then whenever async_probe generic
module parameter is used. This was overlooked when the
form in which in-kernel async probe support was reworked
a bit... Fix this as originally intended.

Cc: Hannes Reinecke <h...@suse.de>
Cc: Dmitry Torokhov <dmitry.torok...@gmail.com>
Cc: sta...@vger.kernel.org (4.2+)
Signed-off-by: Luis R. Rodriguez <mcg...@suse.com>
---
 kernel/module.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/kernel/module.c b/kernel/module.c
index 8f051a106676..88100ea77c55 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -3402,16 +3402,22 @@ out:
 static int unknown_module_param_cb(char *param, char *val, const char *modname,
                                   void *arg)
 {
-       struct module *mod = arg;
+       struct module *mod;
        int ret;
 
        if (strcmp(param, "async_probe") == 0) {
+               mod = arg;
+               if (!mod) {
+                       ret = -ENOENT;
+                       goto out;
+               }
                mod->async_probe_requested = true;
                return 0;
        }
 
        /* Check for magic 'dyndbg' arg */
        ret = ddebug_dyndbg_module_param_cb(param, val, modname);
+out:
        if (ret != 0)
                pr_warn("%s: unknown parameter '%s' ignored\n", modname, param);
        return 0;
@@ -3515,7 +3521,7 @@ static int load_module(struct load_info *info, const char 
__user *uargs,
 
        /* Module is ready to execute: parsing args may do that. */
        after_dashes = parse_args(mod->name, mod->args, mod->kp, mod->num_kp,
-                                 -32768, 32767, NULL,
+                                 -32768, 32767, mod,
                                  unknown_module_param_cb);
        if (IS_ERR(after_dashes)) {
                err = PTR_ERR(after_dashes);
-- 
2.6.2

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