linux-kernel - Re: [PATCH] clk: Fix referring to wrong pointer in devm_clk

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Message-ID: <3896b73a-d8fe-6b92-168a-f30d0a60bbbe@socionext.com>
Date:   Fri, 24 Jun 2022 00:37:23 +0900
From:   Kunihiko Hayashi <hayashi.kunihiko@...ionext.com>
To:     Uwe Kleine-König <u.kleine-koenig@...gutronix.de>
Cc:     Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>, linux-clk@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] clk: Fix referring to wrong pointer in devm_clk_release()

Hi Uwe,

Thank you for pointing out.

On 2022/06/23 16:06, Uwe Kleine-König wrote:
> Hello,
> 
> On Thu, Jun 23, 2022 at 10:02:22AM +0900, Kunihiko Hayashi wrote:
>> At bind phase, __devm_clk_get() calls devres_alloc() to allocate devres,
>> and dr->data is treated as a variable "state".
>>
>> At unbind phase, release_nodes() calls devm_clk_release() specified by
>> devres_alloc().
>>
>> The argument "res" of devm_clk_release() is dr->data, and this entity is
>> "state", however in devm_clk_release(), "*res" is treated as "state",
>> resulting in pointer inconsistency.
>>
>> Unbinding a driver caused a panic.
>>
>>      Unable to handle kernel execute from non-executable memory
>>      at virtual address ffff000100236810
>>      ...
>>      pc : 0xffff000100236810
>>      lr : devm_clk_release+0x6c/0x9c
>>      ...
>>      Call trace:
>>       0xffff000100236810
>>       release_nodes+0xb0/0x150
>>       devres_release_all+0x94/0xf8
>>       device_unbind_cleanup+0x20/0x70
>>       device_release_driver_internal+0x114/0x1a0
>>       device_driver_detach+0x20/0x30
>>
>> Cc: Uwe Kleine-König <u.kleine-koenig@...gutronix.de>
>> Fixes: abae8e57e49a ("clk: generalize devm_clk_get() a bit")
>> Signed-off-by: Kunihiko Hayashi <hayashi.kunihiko@...ionext.com>
> 
> This is already fixed in clk-next:
> 
> 	https://git.kernel.org/pub/scm/linux/kernel/git/clk/linux.git/commit/?h=clk-next&id=8b3d743fc9e2542822826890b482afabf0e7522a

Sorry for not finding the fix patch and duplicating it.
I'm waiting for it to be merged.

Thank you,

---
Best Regards
Kunihiko Hayashi