From 74a5fef7cb0839c6b595f90c7914a62ac9d0bcf9 Mon Sep 17 00:00:00 2001
From: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Date: Wed, 10 Dec 2014 15:51:27 -0800
Subject: [PATCH] lib/lcm.c: ensure correct result whenever it fits
Ensure that lcm(a,b) returns the mathematically correct result, provided
it fits in an unsigned long. The current version returns garbage if a*b
overflows, even if the final result would fit.
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
lib/lcm.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/lib/lcm.c b/lib/lcm.c
index b9c8de461e9e1..01b3aa922dda3 100644
--- a/lib/lcm.c
+++ b/lib/lcm.c
@@ -7,7 +7,7 @@
unsigned long lcm(unsigned long a, unsigned long b)
{
if (a && b)
- return (a * b) / gcd(a, b);
+ return (a / gcd(a, b)) * b;
else if (b)
return b;
--
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