reset: Fix crash when freeing non-existent optional resets

When obtaining one or more optional resets, non-existent resets are
stored as NULL pointers, and all related error and cleanup paths need to
take this into account.

Currently only reset_control_put() and reset_control_bulk_put()
get this right.  All of __reset_control_bulk_get(),
of_reset_control_array_get(), and reset_control_array_put() lack the
proper checking, causing NULL pointer dereferences on failure or
release.

Fix this by moving the existing check from reset_control_bulk_put() to
__reset_control_put_internal(), so it applies to all callers.
The double check in reset_control_put() doesn't hurt.

Fixes: 17c82e206d2a3cd8 ("reset: Add APIs to manage array of resets")
Fixes: 48d71395896d54ee ("reset: Add reset_control_bulk API")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/2440edae7ca8534628cdbaf559ded288f2998178.1701276806.git.geert+renesas@glider.be
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>

diff --git a/drivers/reset/core.c b/drivers/reset/core.c
index 7ece6a8e9858555d0625ba9a0ff820975389e7b3..4d5a78d3c085bc76cda872cc80379b2fa6135ff2 100644 (file)
--- a/drivers/reset/core.c
+++ b/drivers/reset/core.c
@@ -807,6 +807,9 @@ static void __reset_control_put_internal(struct reset_control *rstc)
 {
        lockdep_assert_held(&reset_list_mutex);
 
+       if (IS_ERR_OR_NULL(rstc))
+               return;
+
        kref_put(&rstc->refcnt, __reset_control_release);
 }
 
@@ -1017,11 +1020,8 @@ EXPORT_SYMBOL_GPL(reset_control_put);
 void reset_control_bulk_put(int num_rstcs, struct reset_control_bulk_data *rstcs)
 {
        mutex_lock(&reset_list_mutex);
-       while (num_rstcs--) {
-               if (IS_ERR_OR_NULL(rstcs[num_rstcs].rstc))
-                       continue;
+       while (num_rstcs--)
                __reset_control_put_internal(rstcs[num_rstcs].rstc);
-       }
        mutex_unlock(&reset_list_mutex);
 }
 EXPORT_SYMBOL_GPL(reset_control_bulk_put);