clk: check for invalid parent index of orphans in __clk_init()

If a mux clock is initialised (by hardware or firmware) with an
invalid parent, its ->get_parent() can return an out of range
index.  For example, the generic mux clock attempts to return
-EINVAL, which due to the u8 return type ends up a rather large
number.  Using this index with the parent_names[] array results
in an invalid pointer and (usually) a crash in the following
strcmp().

This patch adds a check for the parent index being in range,
ignoring clocks reporting invalid values.

Signed-off-by: Mans Rullgard <mans@mansr.com>
Tested-by: Rhyland Klein <rklein@nvidia.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>

diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index 43e2c3a..0ebcf44 100644 (file)
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -2437,7 +2437,8 @@ static int __clk_init(struct device *dev, struct clk *clk_user)
        hlist_for_each_entry_safe(orphan, tmp2, &clk_orphan_list, child_node) {
                if (orphan->num_parents && orphan->ops->get_parent) {
                        i = orphan->ops->get_parent(orphan->hw);
-                       if (!strcmp(core->name, orphan->parent_names[i]))
+                       if (i >= 0 && i < orphan->num_parents &&
+                           !strcmp(core->name, orphan->parent_names[i]))
                                clk_core_reparent(orphan, core);
                        continue;
                }