Fixing the glibc adobe flash incompatibility

Magnus Glantz mg at
Wed Nov 17 15:17:30 UTC 2010

On 11/17/2010 11:36 AM, nodata wrote:
> On 17/11/10 10:20, drago01 wrote:
>> On Wed, Nov 17, 2010 at 10:17 AM, nodata<lsof at>   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:
>>>> 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:
>>>> Regards,
>>>> Hans
>>> Is someone talking to Adobe about this?
>> Yes, see
> Adobe benefits from Flash in Linux. So it seems sensible to:
> 1. Get Adobe to commit to a fix soon WITH A $DATE
> 2. Agree to patch the change until $DATE
> 3. Adobe updates Flash, we revert the patch, everyone is happy
I've e-mailed a with Shu Wang at Adobe (who is the assigned contact for 
this issue) about a date when they can have this fixed.
You've got the e-mail thread regarding this below:

On 11/17/2010 10:19 AM, Shu Wang wrote:
> Hi Magnus,
> Maybe months. Thanks.
> Best regards.
> Shu
> -----Original Message-----
> From: Magnus Glantz [mailto:the-mail-address-is-not-this-one at]
> Sent: Wednesday, November 17, 2010 5:15 PM
> To: Shu Wang
> Subject: Re: FP-5739 "Strange sound on mp3 flash website with Fedora 14 x86_64"
> Hi Shu,
> That's is great to hear. Would you guess it's a matter of days, weeks or
> months before this can get fixed?
> If it will take a long time for you to fix this, Fedora may need to look
> at some way to work around this bug.
> Best regards,
> Magnus
> On 11/17/2010 10:06 AM, Shu Wang wrote:
>> Hi Magnus,
>> Thanks very much for your information. Flash Player team is investigating on it. It is in progress. Thanks.
>> Best regards,
>> Shu
>> -----Original Message-----
>> From: Magnus Glantz [mailto:the-mail-address-is-not-this-one at]
>> Sent: Wednesday, November 17, 2010 4:47 PM
>> To: Shu Wang
>> Subject: FP-5739 "Strange sound on mp3 flash website with Fedora 14 x86_64"
>> Hello Shu,
>> I humbly wonder if you may have a time estimate on fixing FP-5739.
>> It is seriously is affecting the ability to listen to sounds played in
>> Flash for the users of Fedora.
>> The issue has been traced to Adobe Flash by maintainers of glibc at Red
>> Hat, Linus Torvalds and others.
>> You may read more about this issue here:

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