[2.30 COMMITTED] S390: Fix handling of needles crossing a page in strstr z15 ifunc-variant. [BZ #25226]

[2.30 COMMITTED] S390: Fix handling of needles crossing a page in strstr z15 ifunc-variant. [BZ #25226]

[Stefan Liebler]

On 11/27/19 12:53 PM, Stefan Liebler wrote:
> On 11/27/19 10:33 AM, Florian Weimer wrote:
>> * Stefan Liebler:
>>
>>> if the specified needle crosses a page-boundary, the s390-z15 ifunc
>>> variant of strstr truncates the needle which results in invalid
>>> results.
>>>
>>> This is fixed by loading the needle beyond the page boundary to v18
>>> instead of v16. The bug is sometimes observable in test-strstr.c in
>>> check1() and check2() as the haystack and needle is stored on
>>> stack. Thus the needle can be on a page boundary.
>>
>> (GNU style is “check1 and check2”, no parentheses.)
>>
>>> check2 is now extended to test haystack / needles located on stack, at
>>> end of page and on two pages.
>>
>> The test change looks okay to me.  I haven't reviewed the assembler
>> change.  I think you can commit that as the architecture maintainer.
>>
>> We will need help from your team with testing the downstream fix.  Do
>> you think we should fix this proactively in Red Hat Enterprise Linux 8.1
>> as well?  It received the backport of the new strstr implementation,
>> too.
>>
>> Thanks,
>> Florian
>>
> 
> Committed it with “check1 and check2” and a reference to the commit 
> 6f47401bd5fc71209219779a0426170a9a7395b0.
> 
> Regarding RHEL, I've recognized that you've opened a RHEL Bugzilla and 
> answered there.
> 
> Thanks,
> Stefan
> 

I've just committed 
https://sourceware.org/git/?p=glibc.git;a=commit;h=f4419b0d0181da28f18cba40068f2e75300f5020