netdev - [PATCH] net: ethernet: ti: Prevent divide-by-zero in cpts_calc_mult

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Message-Id: <20250828092224.46761-1-linmq006@gmail.com>
Date: Thu, 28 Aug 2025 17:22:23 +0800
From: Miaoqian Lin <linmq006@...il.com>
To: Andrew Lunn <andrew+netdev@...n.ch>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>,
	Paolo Abeni <pabeni@...hat.com>,
	Matthias Brugger <matthias.bgg@...il.com>,
	AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Grygorii Strashko <grygorii.strashko@...com>,
	netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	linux-mediatek@...ts.infradead.org
Cc: linmq006@...il.com
Subject: [PATCH] net: ethernet: ti: Prevent divide-by-zero in cpts_calc_mult_shift()

cpts_calc_mult_shift() has a potential divide-by-zero in this line:

        do_div(maxsec, freq);

due to the fact that clk_get_rate() can return zero in certain error
conditions.
Add an explicit check to fix this.

Fixes: 88f0f0b0bebf ("net: ethernet: ti: cpts: calc mult and shift from refclk freq")
Signed-off-by: Miaoqian Lin <linmq006@...il.com>
---
This follows the same pattern as the fix in commit 7ca59947b5fc
("pwm: mediatek: Prevent divide-by-zero in pwm_mediatek_config()").
---
 drivers/net/ethernet/ti/cpts.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/net/ethernet/ti/cpts.c b/drivers/net/ethernet/ti/cpts.c
index 2ba4c8795d60..e4e3409e7648 100644
--- a/drivers/net/ethernet/ti/cpts.c
+++ b/drivers/net/ethernet/ti/cpts.c
@@ -607,6 +607,8 @@ static void cpts_calc_mult_shift(struct cpts *cpts)
 	u32 freq;
 
 	freq = clk_get_rate(cpts->refclk);
+	if (!freq)
+		return;
 
 	/* Calc the maximum number of seconds which we can run before
 	 * wrapping around.
-- 
2.39.5 (Apple Git-154)