[PATCH v2] mtd: rawnand: meson: initialize struct with zeroes

[PATCH v2] mtd: rawnand: meson: initialize struct with zeroes

[Arseniy Krasnov]

This structure must be zeroed, because it's field 'hw->core' is used as
'parent' in 'clk_core_fill_parent_index()', but it will be uninitialized.
This happens, because when this struct is not zeroed, pointer 'hw' is
"initialized" by garbage, which is valid pointer, but points to some
garbage. So 'hw' will be dereferenced, but 'core' contains some random
data which will be interpreted as pointer. The following backtrace is
result of dereference of such pointer:

[    1.081319]  __clk_register+0x414/0x820
[    1.085113]  devm_clk_register+0x64/0xd0
[    1.088995]  meson_nfc_probe+0x258/0x6ec
[    1.092875]  platform_probe+0x70/0xf0
[    1.096498]  really_probe+0xc8/0x3e0
[    1.100034]  __driver_probe_device+0x84/0x190
[    1.104346]  driver_probe_device+0x44/0x120
[    1.108487]  __driver_attach+0xb4/0x220
[    1.112282]  bus_for_each_dev+0x78/0xd0
[    1.116077]  driver_attach+0x2c/0x40
[    1.119613]  bus_add_driver+0x184/0x240
[    1.123408]  driver_register+0x80/0x140
[    1.127203]  __platform_driver_register+0x30/0x40
[    1.131860]  meson_nfc_driver_init+0x24/0x30

Fixes: 1e4d3ba66888 ("mtd: rawnand: meson: fix the clock")
Signed-off-by: Arseniy Krasnov <AVKrasnov@sberdevices.ru>
---
 drivers/mtd/nand/raw/meson_nand.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/mtd/nand/raw/meson_nand.c b/drivers/mtd/nand/raw/meson_nand.c
index 5ee01231ac4c..30e326adabfc 100644
--- a/drivers/mtd/nand/raw/meson_nand.c
+++ b/drivers/mtd/nand/raw/meson_nand.c
@@ -991,7 +991,7 @@ static const struct mtd_ooblayout_ops meson_ooblayout_ops = {
 
 static int meson_nfc_clk_init(struct meson_nfc *nfc)
 {
-	struct clk_parent_data nfc_divider_parent_data[1];
+	struct clk_parent_data nfc_divider_parent_data[1] = {0};
 	struct clk_init_data init = {0};
 	int ret;
 
-- 
2.35.0
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Re: [PATCH v2] mtd: rawnand: meson: initialize struct with zeroes

[Martin Blumenstingl]

Hello Arseniy,

On Tue, Feb 21, 2023 at 11:07 AM Arseniy Krasnov
<AVKrasnov@sberdevices.ru> wrote:
>
> This structure must be zeroed, because it's field 'hw->core' is used as
> 'parent' in 'clk_core_fill_parent_index()', but it will be uninitialized.
> This happens, because when this struct is not zeroed, pointer 'hw' is
> "initialized" by garbage, which is valid pointer, but points to some
> garbage. So 'hw' will be dereferenced, but 'core' contains some random
> data which will be interpreted as pointer.
I think this should be written as "interpreted as a pointer". I'm not
a native English speaker though, so I'm hoping that someone else can
provide feedback as well.

[...]
> Fixes: 1e4d3ba66888 ("mtd: rawnand: meson: fix the clock")
> Signed-off-by: Arseniy Krasnov <AVKrasnov@sberdevices.ru>
Regardless of my comment above:
Acked-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>


Best regards,
Martin

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