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

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Message-Id: <93bf8f574310256fcea50e5c5a62b5c37e20bb14.1686285892.git.christophe.jaillet@wanadoo.fr>
Date:   Fri,  9 Jun 2023 06:45:39 +0200
From:   Christophe JAILLET <christophe.jaillet@...adoo.fr>
To:     Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
        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>
Cc:     linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org,
        Christophe JAILLET <christophe.jaillet@...adoo.fr>,
        linux-arm-kernel@...ts.infradead.org,
        linux-samsung-soc@...r.kernel.org, linux-serial@...r.kernel.org
Subject: [PATCH 2/2] tty: serial: samsung_tty: Fix a memory leak in s3c24xx_serial_getclk() when iterating clk

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))
+				clk_put(*best_clk);
 			*best_clk = clk;
 			best_quot = quot;
 			*clk_num = cnt;
 			deviation = calc_deviation;
+		} else {
+			clk_put(clk);
 		}
 	}
 
-- 
2.34.1