Symbol `SSL_ImplementedCiphers' has different size in shared object, consider re-linking

[Florian Weimer]

On 09/04/2015 03:38 PM, Simo Sorce wrote:
> On Fri, 2015-09-04 at 13:14 +0200, Tomas Mraz wrote:
>> On Pá, 2015-09-04 at 00:38 -0400, Carlos O'Donell wrote:
>>> On 08/28/2015 03:23 PM, Josh Stone wrote:
>>>> I update from nss-3.19.3-1.0.fc22.x86_64 to nss-3.20.0-1.0.fc22.x86_64
>>>> this morning, and now I get this stderr output:
>>>>
>>>> $ /usr/bin/stap -V >/dev/null
>>>> /usr/bin/stap: Symbol `SSL_ImplementedCiphers' has different size in
>>>> shared object, consider re-linking
>>>>
>>>> The message comes from ld.so; that symbol comes from libssl3.so.
>>>>
>>>> Should I be worried about this?  Do we need a rebuild of all
>>>> nss-dependent packages to clear this message?
>>>
>>> Well, it's an ABI break. If you care about ABI issues then the change
>>> causing the breakage needs reverting and the broken packages need to
>>> be rebuilt.
>>
>> The size of the SSL_ImplementedCiphers array is not part of the public
>> API so it is not really an ABI break in practice. However ld.so of
>> course cannot know that. Is there any way to make the message disappear
>> other than rebuild of the dependent package? I am afraid that
>> unfortunately not.
> 
> If it not public why is it exported in the first place ?

The *size* is not part of the ABI, but the symbol is.  ELF keeps track
of data here which is completely pointless.

There is no way to obtain the actual size of the array from C, so I
think the warning could be suppressed using a symbol alias with a
constant size.

-- 
Florian Weimer / Red Hat Product Security