[ 106/147] lib/gcd.c: prevent possible div by 0

From: Ben Hutchings
Date: Sun Oct 14 2012 - 11:05:48 EST


3.2-stable review patch. If anyone has any objections, please let me know.

------------------

From: Davidlohr Bueso <dave@xxxxxxx>

commit e96875677fb2b7cb739c5d7769824dff7260d31d upstream.

Account for all properties when a and/or b are 0:
gcd(0, 0) = 0
gcd(a, 0) = a
gcd(0, b) = b

Fixes no known problems in current kernels.

Signed-off-by: Davidlohr Bueso <dave@xxxxxxx>
Cc: Eric Dumazet <eric.dumazet@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
lib/gcd.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/lib/gcd.c b/lib/gcd.c
index cce4f3c..3657f12 100644
--- a/lib/gcd.c
+++ b/lib/gcd.c
@@ -9,6 +9,9 @@ unsigned long gcd(unsigned long a, unsigned long b)

if (a < b)
swap(a, b);
+
+ if (!b)
+ return a;
while ((r = a % b) != 0) {
a = b;
b = r;


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