linux-kernel - [ 014/133] lib/gcd.c: prevent possible div by 0

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Date:	Thu, 11 Oct 2012 07:50:40 +0900
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	alan@...rguk.ukuu.org.uk, Davidlohr Bueso <dave@....org>,
	Eric Dumazet <eric.dumazet@...il.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>
Subject: [ 014/133] lib/gcd.c: prevent possible div by 0

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

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

From: Davidlohr Bueso <dave@....org>

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@....org>
Cc: Eric Dumazet <eric.dumazet@...il.com>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 lib/gcd.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/lib/gcd.c
+++ b/lib/gcd.c
@@ -9,6 +9,9 @@ unsigned long gcd(unsigned long a, unsig
 
 	if (a < b)
 		swap(a, b);
+
+	if (!b)
+		return a;
 	while ((r = a % b) != 0) {
 		a = b;
 		b = r;


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