This is a note to let you know that I've just added the patch titled
timer: Prevent overflow in apply_slack
to the 3.4-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:
timer-prevent-overflow-in-apply_slack.patch
and it can be found in the queue-3.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 98a01e779f3c66b0b11cd7e64d531c0e41c95762 Mon Sep 17 00:00:00 2001
From: Jiri Bohac <jbohac@xxxxxxx>
Date: Fri, 18 Apr 2014 17:23:11 +0200
Subject: timer: Prevent overflow in apply_slack
From: Jiri Bohac <jbohac@xxxxxxx>
commit 98a01e779f3c66b0b11cd7e64d531c0e41c95762 upstream.
On architectures with sizeof(int) < sizeof (long), the
computation of mask inside apply_slack() can be undefined if the
computed bit is > 32.
E.g. with: expires = 0xffffe6f5 and slack = 25, we get:
expires_limit = 0x20000000e
bit = 33
mask = (1 << 33) - 1 /* undefined */
On x86, mask becomes 1 and and the slack is not applied properly.
On s390, mask is -1, expires is set to 0 and the timer fires immediately.
Use 1UL << bit to solve that issue.
Suggested-by: Deborah Townsend <dstownse@xxxxxxxxxx>
Signed-off-by: Jiri Bohac <jbohac@xxxxxxx>
Link: http://lkml.kernel.org/r/20140418152310.GA13654@xxxxxxxxxxxxxx
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
kernel/timer.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/kernel/timer.c
+++ b/kernel/timer.c
@@ -815,7 +815,7 @@ unsigned long apply_slack(struct timer_l
bit = find_last_bit(&mask, BITS_PER_LONG);
- mask = (1 << bit) - 1;
+ mask = (1UL << bit) - 1;
expires_limit = expires_limit & ~(mask);
Patches currently in stable-queue which might be from jbohac@xxxxxxx are
queue-3.4/timer-prevent-overflow-in-apply_slack.patch
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