From: Jiri Bohac Date: Fri, 18 Apr 2014 15:23:11 +0000 (+0200) Subject: timer: Prevent overflow in apply_slack X-Git-Tag: v3.12.22~121 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=da2eadf4eedb2658cb029ba98b22490c6dcc88a0;p=platform%2Fkernel%2Flinux-stable.git timer: Prevent overflow in apply_slack 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 Signed-off-by: Jiri Bohac Link: http://lkml.kernel.org/r/20140418152310.GA13654@midget.suse.cz Signed-off-by: Thomas Gleixner Signed-off-by: Jiri Slaby --- diff --git a/kernel/timer.c b/kernel/timer.c index 4296d13db3d1..4addfa27f67d 100644 --- a/kernel/timer.c +++ b/kernel/timer.c @@ -822,7 +822,7 @@ 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);