Bug 8504 - The private field 'System.DateTime.to_local_time_span_object' isn't updated under certain conditions
Summary: The private field 'System.DateTime.to_local_time_span_object' isn't updated u...
Status: RESOLVED FIXED
Alias: None
Product: Class Libraries
Classification: Mono
Component: System ()
Version: 2.10.x
Hardware: PC Linux
: --- normal
Target Milestone: Untriaged
Assignee: Bugzilla
URL:
Depends on:
Blocks:
 
Reported: 2012-11-19 10:33 UTC by Greg
Modified: 2013-01-11 11:26 UTC (History)
2 users (show)

Tags:
Is this bug a regression?: ---
Last known good build:

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Status:
RESOLVED FIXED

Description Greg 2012-11-19 10:33:02 UTC
The following condition in the property 'System.DateTime.Now':

    if ((now - last_now) > TimeSpan.TicksPerMinute){

Should be 

    if (Math.abs(now - last_now) > TimeSpan.TicksPerMinute){

The system time may be changed back in time, in this case the static variable 'DateTime.to_local_time_span_object' will never be updated. I think it's a serious issue.

Github Code reference: https://github.com/mono/mono/blob/2.10.8/mcs/class/corlib/System/DateTime.cs#L460

I guess the same issue occurs here: https://github.com/mono/mono/blob/2.10.8/mcs/class/corlib/System/TimeZone.cs#L75

The only workaround I found instead of using 'DateTime.Now' is: 'TimeZone.CurrentTimeZone.ToLocalTime(DateTime.UtcNow)'.
Comment 1 Rodrigo Kumpera 2013-01-11 11:26:24 UTC
Fixed on master.