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| author | Jiri Bohac <jbohac@suse.cz> | 2014-04-18 17:23:11 +0200 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2014-04-30 13:46:17 +0200 |
| commit | 98a01e779f3c66b0b11cd7e64d531c0e41c95762 (patch) | |
| tree | 318f0b56031e4ee8789002f465ccaa30ffedc249 | |
| parent | 012a45e3f4af68e86d85cce060c6c2fed56498b2 (diff) | |
| download | lwn-98a01e779f3c66b0b11cd7e64d531c0e41c95762.tar.gz lwn-98a01e779f3c66b0b11cd7e64d531c0e41c95762.zip | |
timer: Prevent overflow in apply_slack
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@us.ibm.com>
Signed-off-by: Jiri Bohac <jbohac@suse.cz>
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/20140418152310.GA13654@midget.suse.cz
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
| -rw-r--r-- | kernel/timer.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/timer.c b/kernel/timer.c index 87bd529879c2..3bb01a323b2a 100644 --- a/kernel/timer.c +++ b/kernel/timer.c @@ -838,7 +838,7 @@ unsigned long apply_slack(struct timer_list *timer, unsigned long expires) bit = find_last_bit(&mask, BITS_PER_LONG); - mask = (1 << bit) - 1; + mask = (1UL << bit) - 1; expires_limit = expires_limit & ~(mask); |