Re: [PATCH v3 1/3] pinctrl: renesas: rzg2l: Fix NULL pointer dereference in rzg2l_dt_subnode_to_map()

[Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>]

Hi Biju,

On Tue, Aug 15, 2023 at 3:16 PM Biju Das <biju.das.jz@xxxxxxxxxxxxxx> wrote:
> Fix the below random NULL pointer crash during boot by serializing
> pinctrl group and function creation/remove calls in
> rzg2l_dt_subnode_to_map() with mutex lock.
>
> Crash logs:
>  pc : __pi_strcmp+0x20/0x140
>  lr : pinmux_func_name_to_selector+0x68/0xa4
>  Call trace:
>  __pi_strcmp+0x20/0x140
>  pinmux_generic_add_function+0x34/0xcc
>  rzg2l_dt_subnode_to_map+0x314/0x44c
>  rzg2l_dt_node_to_map+0x164/0x194
>  pinctrl_dt_to_map+0x218/0x37c
>  create_pinctrl+0x70/0x3d8
>
> While at it, add comments for bitmap_lock and lock.
>
> Fixes: c4c4637eb57f ("pinctrl: renesas: Add RZ/G2L pin and gpio controller driver")
> Cc: stable@xxxxxxxxxx
> Tested-by: Chris Paterson <Chris.Paterson2@xxxxxxxxxxx>
> Signed-off-by: Biju Das <biju.das.jz@xxxxxxxxxxxxxx>
> ---
> v2->v3:
>  * Added comment for bitmap_lock and lock.
>  * Moved map allocation down to reduce lock section.
>  * Added locks for maps and pinctrl group and function creation/remove
>    calls
>  * Added unlock_and_done label for lock error path.

Thanks for the update!

Upon closer look, I noticed that I had missed that the map allocation
is not global, but local to a specific DT node, so it does not
need protection by a lock.  If no one objects, I will back out that
change myself, queue this patch in renesas-pinctrl-for-v6.6, and send
a PR tomorrow.

Thanks!

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx

In personal conversations with technical people, I call myself a hacker. But
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                                -- Linus Torvalds