linux-kernel - [tip:timers/core] ntp: Fix integer overflow when setting time

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Date:	Thu, 15 Mar 2012 14:53:32 -0700
From:	tip-bot for Sasha Levin <levinsasha928@...il.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, levinsasha928@...il.com,
	hpa@...or.com, mingo@...hat.com, tglx@...utronix.de
Subject: [tip:timers/core] ntp: Fix integer overflow when setting time

Commit-ID:  a078c6d0e6288fad6d83fb6d5edd91ddb7b6ab33
Gitweb:     http://git.kernel.org/tip/a078c6d0e6288fad6d83fb6d5edd91ddb7b6ab33
Author:     Sasha Levin <levinsasha928@...il.com>
AuthorDate: Thu, 15 Mar 2012 12:36:14 -0400
Committer:  Thomas Gleixner <tglx@...utronix.de>
CommitDate: Thu, 15 Mar 2012 21:41:34 +0100

ntp: Fix integer overflow when setting time

'long secs' is passed as divisor to div_s64, which accepts a 32bit
divisor. On 64bit machines that value is trimmed back from 8 bytes
back to 4, causing a divide by zero when the number is bigger than
(1 << 32) - 1 and all 32 lower bits are 0.

Use div64_long() instead.

Signed-off-by: Sasha Levin <levinsasha928@...il.com>
Cc: johnstul@...ibm.com
Link: http://lkml.kernel.org/r/1331829374-31543-2-git-send-email-levinsasha928@gmail.com
Cc: stable@...r.kernel.org
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
---
 kernel/time/ntp.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/kernel/time/ntp.c b/kernel/time/ntp.c
index 17fb1b9..6e039b1 100644
--- a/kernel/time/ntp.c
+++ b/kernel/time/ntp.c
@@ -289,7 +289,7 @@ static inline s64 ntp_update_offset_fll(s64 offset64, long secs)
 
 	time_status |= STA_MODE;
 
-	return div_s64(offset64 << (NTP_SCALE_SHIFT - SHIFT_FLL), secs);
+	return div64_long(offset64 << (NTP_SCALE_SHIFT - SHIFT_FLL), secs);
 }
 
 static void ntp_update_offset(long offset)
--
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