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From: Anna-Maria Behnsen <anna-maria@linutronix.de>
To: Frederic Weisbecker <frederic@kernel.org>, Levi Yun <ppbuk5246@gmail.com>
Cc: tglx@linutronix.de, Markus.Elfring@web.de, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3] time/timgr: Fix wrong reference when level 0 group
 allocation failed
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References: <20240505085709.82688-1-ppbuk5246@gmail.com>
 <20240506041059.86877-1-ppbuk5246@gmail.com>
 <ZjisiuqiR9p76YcJ@localhost.localdomain>
Date: Wed, 08 May 2024 08:16:02 +0200
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Frederic Weisbecker <frederic@kernel.org> writes:

> Le Mon, May 06, 2024 at 05:10:59AM +0100, Levi Yun a =C3=A9crit :
>> When tmigr_setup_groups() failed level 0 group allocation,
>> wrong reference happens on local stack array while intializing timer hie=
rarchy.
>>=20
>> To prevent this, Check loop condition first before initializing timer hi=
erarchy.
>>=20
>> Fixes: 7ee988770326 ("timers: Implement the hierarchical pull model")
>> Signed-off-by: Levi Yun <ppbuk5246@gmail.com>
>> ---
>> v3:
>>     - Fix typo.
>>=20
>> v2:
>> 	- Modify commit message.
>>=20
>>  kernel/time/timer_migration.c | 4 ++--
>>  1 file changed, 2 insertions(+), 2 deletions(-)
>>=20
>> diff --git a/kernel/time/timer_migration.c b/kernel/time/timer_migration=
c
>> index ccba875d2234..84413114db5c 100644
>> --- a/kernel/time/timer_migration.c
>> +++ b/kernel/time/timer_migration.c
>> @@ -1596,7 +1596,7 @@ static int tmigr_setup_groups(unsigned int cpu, un=
signed int node)
>>=20
>>  	} while (i < tmigr_hierarchy_levels);
>>=20
>> -	do {
>> +	while (i > 0) {
>>  		group =3D stack[--i];
>>=20
>>  		if (err < 0) {
>> @@ -1645,7 +1645,7 @@ static int tmigr_setup_groups(unsigned int cpu, un=
signed int node)
>>  				tmigr_connect_child_parent(child, group);
>>  			}
>>  		}
>> -	} while (i > 0);
>> +	}
>
> Looks good to me. But let's wait for Anna-Maria's second look. The group =
setup
> is not my favourite area...
>

Thanks for the fix!

Reviewed-by: Anna-Maria Behnsen <anna-maria@linutronix.de>