clk: check ->determine/round_rate() return value in clk_calc_new_rates

->determine_rate() and ->round_rate() can return the closest rate to the
requested one or an error code.
clk_calc_new_rates is assuming these functions can't return a negative
value, which leads to a undefined behavior when the clk implementation
returns such an error code.
Fix this by returning NULL in case ->determine_rate() or ->round_rate()
returned an error code.

Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Signed-off-by: Michael Turquette <mturquette@linaro.org>

1 files changed, 16 insertions, 7 deletions

diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index fa5a00e5ee41..459ce9da13e0 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -1618,6 +1618,7 @@ static struct clk_core *clk_calc_new_rates(struct clk_core *clk,
         unsigned long min_rate;
         unsigned long max_rate;
         int p_index = 0;
+        long ret;
 
         /* sanity */
         if (IS_ERR_OR_NULL(clk))
@@ -1633,15 +1634,23 @@ static struct clk_core *clk_calc_new_rates(struct clk_core *clk,
         /* find the closest rate and parent clk/rate */
         if (clk->ops->determine_rate) {
                 parent_hw = parent ? parent->hw : NULL;
-                new_rate = clk->ops->determine_rate(clk->hw, rate,
-                                                    min_rate,
-                                                    max_rate,
-                                                    &best_parent_rate,
-                                                    &parent_hw);
+                ret = clk->ops->determine_rate(clk->hw, rate,
+                                               min_rate,
+                                               max_rate,
+                                               &best_parent_rate,
+                                               &parent_hw);
+                if (ret < 0)
+                        return NULL;
+
+                new_rate = ret;
                 parent = parent_hw ? parent_hw->core : NULL;
         } else if (clk->ops->round_rate) {
-                new_rate = clk->ops->round_rate(clk->hw, rate,
-                                                &best_parent_rate);
+                ret = clk->ops->round_rate(clk->hw, rate,
+                                           &best_parent_rate);
+                if (ret < 0)
+                        return NULL;
+
+                new_rate = ret;
                 if (new_rate < min_rate || new_rate > max_rate)
                         return NULL;
         } else if (!parent || !(clk->flags & CLK_SET_RATE_PARENT)) {