aboutsummaryrefslogtreecommitdiff
diff options
context:
space:
mode:
authorBoris Ostrovsky <boris.ostrovsky@oracle.com>2014-05-09 11:11:27 -0400
committerH. Peter Anvin <hpa@zytor.com>2014-05-09 08:45:52 -0700
commit28b92e09e25bdc0ae864b22eacf195a74f861389 (patch)
tree2483505e3c98fd83565a1576af11daf629f8efdf
parentc45f77364ba060395b7eff1bf45e6c537f913380 (diff)
downloadlinux-stericsson-28b92e09e25bdc0ae864b22eacf195a74f861389.tar.gz
x86, vdso, time: Cast tv_nsec to u64 for proper shifting in update_vsyscall()
With tk->wall_to_monotonic.tv_nsec being a 32-bit value on 32-bit systems, (tk->wall_to_monotonic.tv_nsec << tk->shift) in update_vsyscall() may lose upper bits or, worse, add them since compiler will do this: (u64)(tk->wall_to_monotonic.tv_nsec << tk->shift) instead of ((u64)tk->wall_to_monotonic.tv_nsec << tk->shift) So if, for example, tv_nsec is 0x800000 and shift is 8 we will end up with 0xffffffff80000000 instead of 0x80000000. And then we are stuck in the subsequent 'while' loop. We need an explicit cast. Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> Link: http://lkml.kernel.org/r/1399648287-15178-1-git-send-email-boris.ostrovsky@oracle.com Acked-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: <stable@vger.kernel.org> # v3.14 Signed-off-by: H. Peter Anvin <hpa@zytor.com>
-rw-r--r--arch/x86/kernel/vsyscall_gtod.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/x86/kernel/vsyscall_gtod.c b/arch/x86/kernel/vsyscall_gtod.c
index f9c6e56e14b5..9531fbb123ba 100644
--- a/arch/x86/kernel/vsyscall_gtod.c
+++ b/arch/x86/kernel/vsyscall_gtod.c
@@ -43,7 +43,7 @@ void update_vsyscall(struct timekeeper *tk)
vdata->monotonic_time_sec = tk->xtime_sec
+ tk->wall_to_monotonic.tv_sec;
vdata->monotonic_time_snsec = tk->xtime_nsec
- + (tk->wall_to_monotonic.tv_nsec
+ + ((u64)tk->wall_to_monotonic.tv_nsec
<< tk->shift);
while (vdata->monotonic_time_snsec >=
(((u64)NSEC_PER_SEC) << tk->shift)) {