linux-kernel - Re: [PATCH 2/2] tty: serial: samsung_tty: Fix a memory leak in s3c24xx_serial

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Date:   Sat, 10 Jun 2023 12:45:53 +0200
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To:     Andi Shyti <andi.shyti@...nel.org>,
        Christophe JAILLET <christophe.jaillet@...adoo.fr>
Cc:     Alim Akhtar <alim.akhtar@...sung.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jirislaby@...nel.org>,
        Thomas Abraham <thomas.abraham@...aro.org>,
        Kukjin Kim <kgene.kim@...sung.com>,
        linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-samsung-soc@...r.kernel.org, linux-serial@...r.kernel.org
Subject: Re: [PATCH 2/2] tty: serial: samsung_tty: Fix a memory leak in
 s3c24xx_serial_getclk() when iterating clk

On 10/06/2023 12:39, Andi Shyti wrote:
> Hi Christophe,
> 
> On Fri, Jun 09, 2023 at 06:45:39AM +0200, Christophe JAILLET wrote:
>> When the best clk is searched, we iterate over all possible clk.
>>
>> If we find a better match, the previous one, if any, needs to be freed.
>> If a better match has already been found, we still need to free the new
>> one, otherwise it leaks.
>>
>> Fixes: 5f5a7a5578c5 ("serial: samsung: switch to clkdev based clock lookup")
>> Signed-off-by: Christophe JAILLET <christophe.jaillet@...adoo.fr>
>> ---
>> This patch is speculative. Review with care.
>>
>> I think that some clk_put() are also missing somewhere else in the driver
>> but won't be able to investigate further.
>> ---
>>  drivers/tty/serial/samsung_tty.c | 8 ++++++++
>>  1 file changed, 8 insertions(+)
>>
>> diff --git a/drivers/tty/serial/samsung_tty.c b/drivers/tty/serial/samsung_tty.c
>> index dd751e7010e3..c07877dd25fa 100644
>> --- a/drivers/tty/serial/samsung_tty.c
>> +++ b/drivers/tty/serial/samsung_tty.c
>> @@ -1488,10 +1488,18 @@ static unsigned int s3c24xx_serial_getclk(struct s3c24xx_uart_port *ourport,
>>  			calc_deviation = -calc_deviation;
>>  
>>  		if (calc_deviation < deviation) {
>> +			/*
>> +			 * If we find a better clk, release the previous one, if
>> +			 * any.
>> +			 */
>> +			if (!IS_ERR(*best_clk))
> 
> what is the case when *best_clk has an error in it?

The initial one? Open the place where the function is being called.

Best regards,
Krzysztof