sparc: Fix cleanup crash in bbc_envctrl_cleanup()

If kthread_run() fails or never gets to run we'll have NULL
or a pointer encoded error in kenvctrld_task, rather than
a legitimate task pointer.

So this makes bbc_envctrl_cleanup() crash as it passed this
bogus pointer into kthread_stop().

Reported-by: BERTRAND Joël <joel.bertrand@systella.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 8 insertions, 3 deletions

diff --git a/drivers/sbus/char/bbc_envctrl.c b/drivers/sbus/char/bbc_envctrl.c
index 15dab96d05e3..7c815d3327f7 100644
--- a/drivers/sbus/char/bbc_envctrl.c
+++ b/drivers/sbus/char/bbc_envctrl.c
@@ -537,8 +537,12 @@ int bbc_envctrl_init(struct bbc_i2c_bus *bp)
         }
         if (temp_index != 0 && fan_index != 0) {
                 kenvctrld_task = kthread_run(kenvctrld, NULL, "kenvctrld");
-                if (IS_ERR(kenvctrld_task))
-                        return PTR_ERR(kenvctrld_task);
+                if (IS_ERR(kenvctrld_task)) {
+                        int err = PTR_ERR(kenvctrld_task);
+
+                        kenvctrld_task = NULL;
+                        return err;
+                }
         }
 
         return 0;
@@ -561,7 +565,8 @@ void bbc_envctrl_cleanup(struct bbc_i2c_bus *bp)
         struct bbc_cpu_temperature *tp, *tpos;
         struct bbc_fan_control *fp, *fpos;
 
-        kthread_stop(kenvctrld_task);
+        if (kenvctrld_task)
+                kthread_stop(kenvctrld_task);
 
         list_for_each_entry_safe(tp, tpos, &bp->temps, bp_list) {
                 list_del(&tp->bp_list);