linux-kernel - [PATCH 5.15 672/917] clk: at91: clk-master: check if div or pres is zero

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Date:   Mon, 15 Nov 2021 18:02:47 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Claudiu Beznea <claudiu.beznea@...rochip.com>,
        Nicolas Ferre <nicolas.ferre@...rochip.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.15 672/917] clk: at91: clk-master: check if div or pres is zero

From: Claudiu Beznea <claudiu.beznea@...rochip.com>

[ Upstream commit c2910c00fee4cbb7b222d6e02846adef9ae4135a ]

Check if div or pres is zero before using it as argument for ffs().
In case div is zero ffs() will return 0 and thus substracting from
zero will lead to invalid values to be setup in registers.

Fixes: 7a110b9107ed8 ("clk: at91: clk-master: re-factor master clock")
Fixes: 75c88143f3b87 ("clk: at91: clk-master: add master clock support for SAMA7G5")
Signed-off-by: Claudiu Beznea <claudiu.beznea@...rochip.com>
Link: https://lore.kernel.org/r/20211011112719.3951784-9-claudiu.beznea@microchip.com
Acked-by: Nicolas Ferre <nicolas.ferre@...rochip.com>
Signed-off-by: Stephen Boyd <sboyd@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/clk/at91/clk-master.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/clk/at91/clk-master.c b/drivers/clk/at91/clk-master.c
index a80427980bf73..2e410815a3405 100644
--- a/drivers/clk/at91/clk-master.c
+++ b/drivers/clk/at91/clk-master.c
@@ -280,7 +280,7 @@ static int clk_master_pres_set_rate(struct clk_hw *hw, unsigned long rate,
 
 	else if (pres == 3)
 		pres = MASTER_PRES_MAX;
-	else
+	else if (pres)
 		pres = ffs(pres) - 1;
 
 	spin_lock_irqsave(master->lock, flags);
@@ -610,7 +610,7 @@ static int clk_sama7g5_master_set_rate(struct clk_hw *hw, unsigned long rate,
 
 	if (div == 3)
 		div = MASTER_PRES_MAX;
-	else
+	else if (div)
 		div = ffs(div) - 1;
 
 	spin_lock_irqsave(master->lock, flags);
-- 
2.33.0