FAQ Search Today's Posts Mark Forums Read
» Video Reviews

» Linux Archive

Linux-archive is a website aiming to archive linux email lists and to make them easily accessible for linux users/developers.


» Sponsor

» Partners

» Sponsor

Go Back   Linux Archive > Redhat > Fedora Development

 
 
LinkBack Thread Tools
 
Old 11-17-2010, 06:57 AM
Hans de Goede
 
Default Fixing the glibc adobe flash incompatibility

Hi all,

For those who do not know it yet, recent Fedora glibc updates include
an optimized memcpy (which gets used on some processors) which breaks the
64 bit adobe flash plugin.

The problem has been analyzed and is known, as well as a fix for it, see:
https://bugzilla.redhat.com/show_bug.cgi?id=638477

The problem still exists however. The glibc developers say that this is
not a glibc bug, but a flash plugin bug. And technically they are 100%
correct, and the adobe flash plugin is a buggy .... (no surprise there).
To be specific the flash plugin is doing overlapping memcpy-s which is
clearly not how memcpy is supposed to be used. But the way the flash
plugin does overlapping memcpy's happens to work fine as long as one as
the c library does the memcpy-s in forward direction. And the new memcpy
implementation does the memcpy in backward direction.

The glibc developers being technically 100% correct is not helping our
end users in this case though. So we (The Fedora project) need to come up
with a solution to help our end users, many of whom want to use the adobe
flash plugin.

This solution could be reverting the problem causing glibc change, or
maybe changing it to do forward memcpy's while still using the new SSE
instructions, or something more specific to the flash plugin, as long
as it will automatically fix things with a yum upgrade without requiring
any further user intervention.

I would also like to point out that if this were to happen in Ubuntu
which we sometimes look at jealously for getting more attention / users
then us, the glibc change would likely be reverted immediately, as that
is the right thing to do from an end user pov.

I've filed a ticket for FESCo to look into this, as I believe this
makes us look really bad, and the glibc maintainers do not seem to be
willing to fix it without some sort of intervention:
https://fedorahosted.org/fesco/ticket/501

Regards,

Hans
--
devel mailing list
devel@lists.fedoraproject.org
https://admin.fedoraproject.org/mailman/listinfo/devel
 
Old 11-17-2010, 08:17 AM
nodata
 
Default Fixing the glibc adobe flash incompatibility

On 17/11/10 08:57, Hans de Goede wrote:
> Hi all,
>
> For those who do not know it yet, recent Fedora glibc updates include
> an optimized memcpy (which gets used on some processors) which breaks the
> 64 bit adobe flash plugin.
>
> The problem has been analyzed and is known, as well as a fix for it, see:
> https://bugzilla.redhat.com/show_bug.cgi?id=638477
>
> The problem still exists however. The glibc developers say that this is
> not a glibc bug, but a flash plugin bug. And technically they are 100%
> correct, and the adobe flash plugin is a buggy .... (no surprise there).
> To be specific the flash plugin is doing overlapping memcpy-s which is
> clearly not how memcpy is supposed to be used. But the way the flash
> plugin does overlapping memcpy's happens to work fine as long as one as
> the c library does the memcpy-s in forward direction. And the new memcpy
> implementation does the memcpy in backward direction.
>
> The glibc developers being technically 100% correct is not helping our
> end users in this case though. So we (The Fedora project) need to come up
> with a solution to help our end users, many of whom want to use the adobe
> flash plugin.
>
> This solution could be reverting the problem causing glibc change, or
> maybe changing it to do forward memcpy's while still using the new SSE
> instructions, or something more specific to the flash plugin, as long
> as it will automatically fix things with a yum upgrade without requiring
> any further user intervention.
>
> I would also like to point out that if this were to happen in Ubuntu
> which we sometimes look at jealously for getting more attention / users
> then us, the glibc change would likely be reverted immediately, as that
> is the right thing to do from an end user pov.
>
> I've filed a ticket for FESCo to look into this, as I believe this
> makes us look really bad, and the glibc maintainers do not seem to be
> willing to fix it without some sort of intervention:
> https://fedorahosted.org/fesco/ticket/501
>
> Regards,
>
> Hans

Is someone talking to Adobe about this?
--
devel mailing list
devel@lists.fedoraproject.org
https://admin.fedoraproject.org/mailman/listinfo/devel
 
Old 11-17-2010, 08:20 AM
drago01
 
Default Fixing the glibc adobe flash incompatibility

On Wed, Nov 17, 2010 at 10:17 AM, nodata <lsof@nodata.co.uk> wrote:
> On 17/11/10 08:57, Hans de Goede wrote:
>> Hi all,
>>
>> For those who do not know it yet, recent Fedora glibc updates include
>> an optimized memcpy (which gets used on some processors) which breaks the
>> 64 bit adobe flash plugin.
>>
>> The problem has been analyzed and is known, as well as a fix for it, see:
>> https://bugzilla.redhat.com/show_bug.cgi?id=638477
>>
>> The problem still exists however. The glibc developers say that this is
>> not a glibc bug, but a flash plugin bug. And technically they are 100%
>> correct, and the adobe flash plugin is a buggy .... (no surprise there).
>> To be specific the flash plugin is doing overlapping memcpy-s which is
>> clearly not how memcpy is supposed to be used. But the way the flash
>> plugin does overlapping memcpy's happens to work fine as long as one as
>> the c library does the memcpy-s in forward direction. And the new memcpy
>> implementation does the memcpy in backward direction.
>>
>> The glibc developers being technically 100% correct is not helping our
>> end users in this case though. So we (The Fedora project) need to come up
>> with a solution to help our end users, many of whom want to use the adobe
>> flash plugin.
>>
>> This solution could be reverting the problem causing glibc change, or
>> maybe changing it to do forward memcpy's while still using the new SSE
>> instructions, or something more specific to the flash plugin, as long
>> as it will automatically fix things with a yum upgrade without requiring
>> any further user intervention.
>>
>> I would also like to point out that if this were to happen in Ubuntu
>> which we sometimes look at jealously for getting more attention / users
>> then us, the glibc change would likely be reverted immediately, as that
>> is the right thing to do from an end user pov.
>>
>> I've filed a ticket for FESCo to look into this, as I believe this
>> makes us look really bad, and the glibc maintainers do not seem to be
>> willing to fix it without some sort of intervention:
>> https://fedorahosted.org/fesco/ticket/501
>>
>> Regards,
>>
>> Hans
>
> Is someone talking to Adobe about this?

Yes, see https://bugs.adobe.com/jira/browse/FP-5739
--
devel mailing list
devel@lists.fedoraproject.org
https://admin.fedoraproject.org/mailman/listinfo/devel
 
Old 11-17-2010, 09:27 AM
Michel Alexandre Salim
 
Default Fixing the glibc adobe flash incompatibility

On Wed, 17 Nov 2010 10:20:35 +0100, drago01 wrote:

> On Wed, Nov 17, 2010 at 10:17 AM, nodata <lsof@nodata.co.uk> wrote:
>> On 17/11/10 08:57, Hans de Goede wrote:
>>> Hi all,
>>>
>>> For those who do not know it yet, recent Fedora glibc updates include
>>> an optimized memcpy (which gets used on some processors) which breaks
>>> the 64 bit adobe flash plugin.
>>>
>>> The problem has been analyzed and is known, as well as a fix for it,
>>> see: https://bugzilla.redhat.com/show_bug.cgi?id=638477
>>>
...
>> I've filed a ticket for FESCo to look into this, as I believe this
>>> makes us look really bad, and the glibc maintainers do not seem to be
>>> willing to fix it without some sort of intervention:
>>> https://fedorahosted.org/fesco/ticket/501
>>>
>>> Regards,
>>>
>>> Hans
>>
>> Is someone talking to Adobe about this?
>
> Yes, see https://bugs.adobe.com/jira/browse/FP-5739

So this problem would not have been there in the first place had the
Flash plugin just reuse some other MP3 decoding library (e.g. through
Gstreamer) rather than rolling out their own, right?


--
Michel Alexandre Salim
Fedora Project Contributor: http://fedoraproject.org/

Email: salimma@fedoraproject.org | GPG key ID: 78884778
Jabber: hircus@jabber.ccc.de | IRC: hircus@irc.freenode.net

() ascii ribbon campaign - against html e-mail
/ www.asciiribbon.org - against proprietary attachments

--
devel mailing list
devel@lists.fedoraproject.org
https://admin.fedoraproject.org/mailman/listinfo/devel
 

Thread Tools




All times are GMT. The time now is 03:57 AM.

VBulletin, Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Content Relevant URLs by vBSEO ©2007, Crawlability, Inc.
Copyright 2007 - 2008, www.linux-archive.org