netdev - [PATCH] maketable: Add check for ZERO for variable sigma2

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Date: Sun,  7 Jan 2024 00:14:22 +0300
From: Maks Mishin <maks.mishinfz@...il.com>
To: Stephen Hemminger <stephen@...workplumber.org>
Cc: Maks Mishin <maks.mishinFZ@...il.com>,
	netdev@...r.kernel.org
Subject: [PATCH] maketable: Add check for ZERO for variable sigma2

If variable `limit` == 1, then `n` == 1 and then second for-loop will
not do because of variable `sigma2` maybe ZERO.
Added check for ZERO for `sigma2` before it is used as denominator.

Signed-off-by: Maks Mishin <maks.mishinFZ@...il.com>
---
 netem/maketable.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/netem/maketable.c b/netem/maketable.c
index ad8620a4..56b1d0bb 100644
--- a/netem/maketable.c
+++ b/netem/maketable.c
@@ -68,6 +68,10 @@ arraystats(double *x, int limit, double *mu, double *sigma, double *rho)
 		sigma2 += ((double)x[i-1] - *mu)*((double)x[i-1] - *mu);
 
 	}
+	if (sigma2 == 0) {
+		perror("Division by zero in top/sigma2");
+		exit(3);
+	}
 	*rho = top/sigma2;
 }
 
-- 
2.34.1