[PATCH] clk: eswin: Zero-initialize stack-allocated clk_init_data

[kdamaski <kostas.damaskinakis@gmail.com>]

From: Kostas Damaskinakis <kostas.damaskinakis@gmail.com>

eswin_clk_register_pll() and eswin_register_clkdiv() declare a struct
clk_init_data on the stack and only initialize some of its fields
(parent_data respectively parent_hws). clk_core_populate_parent_map()
checks parent_names first and parent_data second before falling back
to parent_hws, so leftover stack garbage in the uninitialized fields
hijacks parent resolution and the clk core dereferences a bogus
pointer:

  Unable to handle kernel NULL pointer dereference at virtual address 000000000000000c
  Oops [#1]
  epc : __clk_register+0x31a/0x7f0
  [<ffffffff805dc774>] __clk_register+0x31a/0x7f0
  [<ffffffff805dcd76>] devm_clk_hw_register+0x2a/0x94
  [<ffffffff805e319a>] eswin_register_clkdiv+0x80/0xd0
  [<ffffffff805e34a0>] eswin_clk_register_clks+0x162/0x1a0
  [<ffffffff805e3736>] eic7700_clk_probe+0x146/0x180
  [<ffffffff8065d23c>] platform_probe+0x3c/0x7a

Observed on EIC7700 hardware (with the driver backported to a 6.17
tree); whether the bug triggers depends entirely on what the stack
happens to contain when the registration helpers run.

Zero-initialize both structures.

Fixes: cd44f127c1d4 ("clk: eswin: Add eic7700 clock driver")
Signed-off-by: Kostas Damaskinakis <kostas.damaskinakis@gmail.com>
---
 drivers/clk/eswin/clk.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/clk/eswin/clk.c b/drivers/clk/eswin/clk.c
index e09a52cc3..79d1e4c5e 100644
--- a/drivers/clk/eswin/clk.c
+++ b/drivers/clk/eswin/clk.c
@@ -204,7 +204,7 @@ int eswin_clk_register_pll(struct device *dev, struct eswin_pll_clock *clks,
 			   int nums, struct eswin_clock_data *data)
 {
 	struct eswin_clk_pll *p_clk = NULL;
-	struct clk_init_data init;
+	struct clk_init_data init = {};
 	struct clk_hw *clk_hw;
 	int i, ret;
 
@@ -419,7 +419,7 @@ struct clk_hw *eswin_register_clkdiv(struct device *dev, unsigned int id,
 				     unsigned long priv_flag, spinlock_t *lock)
 {
 	struct eswin_divider_clock *dclk;
-	struct clk_init_data init;
+	struct clk_init_data init = {};
 	struct clk_hw *clk_hw;
 	int ret;
 
-- 
2.34.1