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 12:57:10 +0200
From:   Andi Shyti <andi.shyti@...nel.org>
To:     Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
Cc:     Christophe JAILLET <christophe.jaillet@...adoo.fr>,
        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

Hi Krzysztof,

> On Sat, Jun 10, 2023 at 12:45:53PM +0200, Krzysztof Kozlowski wrote:
> 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.

Right!

Reviewed-by: Andi Shyti <andi.shyti@...nel.org> 

Andi

> 
> Best regards,
> Krzysztof
>