This is a note to let you know that I've just added the patch titled
ntp: Fixup adjtimex freq validation on 32-bit systems
to the 3.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
ntp-fixup-adjtimex-freq-validation-on-32-bit-systems.patch
and it can be found in the queue-3.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 29183a70b0b828500816bd794b3fe192fce89f73 Mon Sep 17 00:00:00 2001
From: John Stultz <john.stultz@xxxxxxxxxx>
Date: Mon, 9 Feb 2015 23:30:36 -0800
Subject: ntp: Fixup adjtimex freq validation on 32-bit systems
From: John Stultz <john.stultz@xxxxxxxxxx>
commit 29183a70b0b828500816bd794b3fe192fce89f73 upstream.
Additional validation of adjtimex freq values to avoid
potential multiplication overflows were added in commit
5e5aeb4367b (time: adjtimex: Validate the ADJ_FREQUENCY values)
Unfortunately the patch used LONG_MAX/MIN instead of
LLONG_MAX/MIN, which was fine on 64-bit systems, but being
much smaller on 32-bit systems caused false positives
resulting in most direct frequency adjustments to fail w/
EINVAL.
ntpd only does direct frequency adjustments at startup, so
the issue was not as easily observed there, but other time
sync applications like ptpd and chrony were more effected by
the bug.
See bugs:
https://bugzilla.kernel.org/show_bug.cgi?id=92481
https://bugzilla.redhat.com/show_bug.cgi?id=1188074
This patch changes the checks to use LLONG_MAX for
clarity, and additionally the checks are disabled
on 32-bit systems since LLONG_MAX/PPM_SCALE is always
larger then the 32-bit long freq value, so multiplication
overflows aren't possible there.
Reported-by: Josh Boyer <jwboyer@xxxxxxxxxxxxxxxxx>
Reported-by: George Joseph <george.joseph@xxxxxxxxxxxxx>
Tested-by: George Joseph <george.joseph@xxxxxxxxxxxxx>
Signed-off-by: John Stultz <john.stultz@xxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Sasha Levin <sasha.levin@xxxxxxxxxx>
Link: http://lkml.kernel.org/r/1423553436-29747-1-git-send-email-john.stultz@xxxxxxxxxx
[ Prettified the changelog and the comments a bit. ]
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
kernel/time/ntp.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)
--- a/kernel/time/ntp.c
+++ b/kernel/time/ntp.c
@@ -631,10 +631,14 @@ int ntp_validate_timex(struct timex *txc
if ((txc->modes & ADJ_SETOFFSET) && (!capable(CAP_SYS_TIME)))
return -EPERM;
- if (txc->modes & ADJ_FREQUENCY) {
- if (LONG_MIN / PPM_SCALE > txc->freq)
+ /*
+ * Check for potential multiplication overflows that can
+ * only happen on 64-bit systems:
+ */
+ if ((txc->modes & ADJ_FREQUENCY) && (BITS_PER_LONG == 64)) {
+ if (LLONG_MIN / PPM_SCALE > txc->freq)
return -EINVAL;
- if (LONG_MAX / PPM_SCALE < txc->freq)
+ if (LLONG_MAX / PPM_SCALE < txc->freq)
return -EINVAL;
}
Patches currently in stable-queue which might be from john.stultz@xxxxxxxxxx are
queue-3.14/ntp-fixup-adjtimex-freq-validation-on-32-bit-systems.patch
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