[PATCH] Fix segfault in gcov.c (PR gcov-profile/81561).

[Richard Biener]

On Tue, Aug 1, 2017 at 2:02 PM, Martin Liška <mliska@suse.cz> wrote:
> On 07/27/2017 01:48 PM, Richard Biener wrote:
>>
>> On Thu, Jul 27, 2017 at 12:12 PM, Martin Liška <mliska@suse.cz> wrote:
>>>
>>> Hello.
>>>
>>> As reported in mentioned PR, we segfault in gcov tool when one uses -a.
>>> It's caused by fact
>>> that vectors blocks and block_lists have indices kept in sync and as one
>>> removes an element
>>> from blocks via:
>>>     blocked.erase (it);
>>>
>>> Then calling recursively the same function breaks the synchronization.
>>> The patch was originally
>>> written by Joshua (adding him to CC). If I'm correct calling:
>>>
>>> -    unblock (u, blocked, block_lists);
>>>
>>> does not make sense as we've already removed 'u'. Plus one needs to put
>>> content of block_lists[index]
>>> to a separate vector in order to not to break iteration.
>>>
>>> Patch can bootstrap on ppc64le-redhat-linux and survives regression
>>> tests.
>>> And fixed the problem reported in opensuse bugzilla (mentioned in the GCC
>>> bugzilla PR).
>>>
>>> Ready to be installed?
>>
>>
>> Looks good to me but please wait for Joshua to confirm.
>
>
> Hello.
>
> No reply yet, I've just verified that in the article the function (unblock)
> does the same as with the patch:
> https://pdfs.semanticscholar.org/72c3/b54c1aea0a3193bad9721727a1798101ab26.pdf
> (page 3).
>
> I would be happy to have the patch in 7.2.
> Can we Richi catch the deadline?

Sure, go ahead now.

Thanks,
Richard.

> Thanks,
> Martin
>
>
>>
>> Did you manage to extract a testcase?
>>
>> Thanks,
>> Richard.
>>
>>> Martin
>>>
>>>
>>> gcc/ChangeLog:
>>>
>>> 2017-07-26  Martin Liska  <mliska@suse.cz>
>>>
>>>          PR gcov-profile/81561
>>>          * gcov.c (unblock): Make unblocking safe as we need to preserve
>>>          index correspondence of blocks and block_lists.
>>> ---
>>>   gcc/gcov.c | 10 +++++++---
>>>   1 file changed, 7 insertions(+), 3 deletions(-)
>>>
>>>
>>>
>