linux-kernel - [PATCH] ssb-main: Fix division by zero in ssb_calc_clock

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Date:   Wed, 30 Aug 2023 11:27:59 +0300
From:   Rand Deeb <deeb.rand@...fident.ru>
To:     Michael Buesch <m@...s.ch>, linux-wireless@...r.kernel.org,
        linux-kernel@...r.kernel.org
Cc:     lvc-project@...uxtesting.org, voskresenski.stanislav@...fident.ru,
        Rand Deeb <deeb.rand@...fident.ru>
Subject: [PATCH] ssb-main: Fix division by zero in ssb_calc_clock_rate()

In ssb_calc_clock_rate(), the value of m1 may be zero because it is
initialized using clkfactor_f6_resolv(). This function could return
zero, so there is a possibility of dividing by zero, we fixed it by
checking the values before dividing.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Signed-off-by: Rand Deeb <deeb.rand@...fident.ru>
---
 drivers/ssb/main.c | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/drivers/ssb/main.c b/drivers/ssb/main.c
index 0a26984acb2c..e0776a16d04d 100644
--- a/drivers/ssb/main.c
+++ b/drivers/ssb/main.c
@@ -903,13 +903,21 @@ u32 ssb_calc_clock_rate(u32 plltype, u32 n, u32 m)
 		case SSB_CHIPCO_CLK_MC_BYPASS:
 			return clock;
 		case SSB_CHIPCO_CLK_MC_M1:
-			return (clock / m1);
+			if (m1 != 0)
+				return (clock / m1);
+			break;
 		case SSB_CHIPCO_CLK_MC_M1M2:
-			return (clock / (m1 * m2));
+			if ((m1 * m2) != 0)
+				return (clock / (m1 * m2));
+			break;
 		case SSB_CHIPCO_CLK_MC_M1M2M3:
-			return (clock / (m1 * m2 * m3));
+			if ((m1 * m2 * m3) != 0)
+				return (clock / (m1 * m2 * m3));
+			break;
 		case SSB_CHIPCO_CLK_MC_M1M3:
-			return (clock / (m1 * m3));
+			if ((m1 * m3) != 0)
+				return (clock / (m1 * m3));
+			break;
 		}
 		return 0;
 	case SSB_PLLTYPE_2:
-- 
2.34.1