Commit-ID: 52d189f1b38810b1b483d5bac2e4fa90b9afd372
Gitweb: http://git.kernel.org/tip/52d189f1b38810b1b483d5bac2e4fa90b9afd372
Author: Sasha Levin <sasha.levin@xxxxxxxxxx>
AuthorDate: Thu, 3 Dec 2015 15:46:48 -0500
Committer: John Stultz <john.stultz@xxxxxxxxxx>
CommitDate: Thu, 10 Dec 2015 22:41:05 -0800
ntp: Verify offset doesn't overflow in ntp_update_offset
We need to make sure that the offset is valid before manipulating it,
otherwise it might overflow on the multiplication.
Cc: Sasha Levin <sasha.levin@xxxxxxxxxx>
Cc: Richard Cochran <richardcochran@xxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sasha.levin@xxxxxxxxxx>
[jstultz: Reworked one of the checks so it makes more sense]
Signed-off-by: John Stultz <john.stultz@xxxxxxxxxx>
---
kernel/time/ntp.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)
diff --git a/kernel/time/ntp.c b/kernel/time/ntp.c
index 149cc80..125fc03 100644
--- a/kernel/time/ntp.c
+++ b/kernel/time/ntp.c
@@ -297,15 +297,17 @@ static void ntp_update_offset(long offset)
if (!(time_status & STA_PLL))
return;
- if (!(time_status & STA_NANO))
+ if (!(time_status & STA_NANO)) {
+ /* Make sure the multiplication below won't overflow */
+ offset = clamp(offset, -USEC_PER_SEC, USEC_PER_SEC);
offset *= NSEC_PER_USEC;
+ }
/*
* Scale the phase adjustment and
* clamp to the operating range.
*/
- offset = min(offset, MAXPHASE);
- offset = max(offset, -MAXPHASE);
+ offset = clamp(offset, -MAXPHASE, MAXPHASE);
/*
* Select how the frequency is to be controlled
--
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