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List:       kde-frameworks-devel
Subject:    Re: Review Request 128893: Fix sorted insert (aka flat_map like insert).
From:       Christoph Cullmann <cullmann () kde ! org>
Date:       2016-09-11 20:40:40
Message-ID: 20160911204040.10006.52141 () mimi ! kde ! org
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This is an automatically generated e-mail. To reply, visit:
https://git.reviewboard.kde.org/r/128893/
-----------------------------------------------------------

(Updated Sept. 11, 2016, 4:40 p.m.)


Status
------

This change has been marked as submitted.


Review request for KDE Frameworks and Boudhayan Gupta.


Changes
-------

Submitted with commit 6e5b41e88d92c90df8e54d99163cea08f17d0554 by Christoph Cullmann \
to branch master.


Repository: baloo


Description
-------

Old code was plain wrong:

-        auto it = std::upper_bound(subDocs.begin(), subDocs.end(), id);
-
-        // Merge the id if it does not
-        auto prev = it - 1;
-        if (*prev != id) {
-            subDocs.insert(it, id);
-        }


=> you deref begin()-1 in my test case

=> BAM ;)

valgrind backtrace for old code (moved it to template method)

0
PASS   : DocumentUrlDBTest::testGetId()
it == begin 1
==22283== Invalid read of size 8
==22283==    at 0x406F20: void Baloo::sortedIdInsert<std::vector<unsigned long long, \
std::allocator<unsigned long long> >, unsigned long long>(std::vector<unsigned long \
long, std::allocator<unsigned long long> >&, unsigned long long const&) \
(idutils.h:101) ==22283==    by 0x406965: DocumentUrlDBTest::testSortedIdInsert() \
(documenturldbtest.cpp:158) ==22283==    by 0x404DD9: \
DocumentUrlDBTest::qt_static_metacall(QObject*, QMetaObject::Call, int, void**) \
(documenturldbtest.moc:99) ==22283==    by 0x57F90BD: QMetaMethod::invoke(QObject*, \
Qt::ConnectionType, QGenericReturnArgument, QGenericArgument, QGenericArgument, \
QGenericArgument, QGenericArgument, QGenericArgument, QGenericArgument, \
QGenericArgument, QGenericArgument, QGenericArgument, QGenericArgument) const (in \
/usr/lib/libQt5Core.so.5.7.0) ==22283==    by 0x4E489D6: ??? (in \
/usr/lib/libQt5Test.so.5.7.0) ==22283==    by 0x4E49405: ??? (in \
/usr/lib/libQt5Test.so.5.7.0) ==22283==    by 0x4E49A51: ??? (in \
/usr/lib/libQt5Test.so.5.7.0) ==22283==    by 0x4E49F60: QTest::qExec(QObject*, int, \
char**) (in /usr/lib/libQt5Test.so.5.7.0) ==22283==    by 0x404CF1: main \
(documenturldbtest.cpp:167) ==22283==  Address 0xbf25418 is 8 bytes before a block of \
size 8 alloc'd ==22283==    at 0x4C2A0FC: operator new(unsigned long) (in \
/usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so) ==22283==    by 0x40AF63: \
__gnu_cxx::new_allocator<unsigned long long>::allocate(unsigned long, void const*) \
(new_allocator.h:104) ==22283==    by 0x40AD46: \
std::allocator_traits<std::allocator<unsigned long long> \
>::allocate(std::allocator<unsigned long long>&, unsigned long) (alloc_traits.h:416) \
> ==22283==    by 0x40A171: std::_Vector_base<unsigned long long, \
> std::allocator<unsigned long long> >::_M_allocate(unsigned long) (stl_vector.h:170)
==22283==    by 0x409151: void std::vector<unsigned long long, \
std::allocator<unsigned long long> >::_M_emplace_back_aux<unsigned long \
long>(unsigned long long&&) (vector.tcc:412) ==22283==    by 0x40886C: void \
std::vector<unsigned long long, std::allocator<unsigned long long> \
>::emplace_back<unsigned long long>(unsigned long long&&) (vector.tcc:101) ==22283==  \
> by 0x406E55: std::vector<unsigned long long, std::allocator<unsigned long long> \
> >::push_back(unsigned long long&&) (stl_vector.h:933)
==22283==    by 0x40694A: DocumentUrlDBTest::testSortedIdInsert() \
(documenturldbtest.cpp:155) ==22283==    by 0x404DD9: \
DocumentUrlDBTest::qt_static_metacall(QObject*, QMetaObject::Call, int, void**) \
(documenturldbtest.moc:99) ==22283==    by 0x57F90BD: QMetaMethod::invoke(QObject*, \
Qt::ConnectionType, QGenericReturnArgument, QGenericArgument, QGenericArgument, \
QGenericArgument, QGenericArgument, QGenericArgument, QGenericArgument, \
QGenericArgument, QGenericArgument, QGenericArgument, QGenericArgument) const (in \
/usr/lib/libQt5Core.so.5.7.0) ==22283==    by 0x4E489D6: ??? (in \
/usr/lib/libQt5Test.so.5.7.0) ==22283==    by 0x4E49405: ??? (in \
/usr/lib/libQt5Test.so.5.7.0) ==22283==


Bug report:

https://bugs.kde.org/show_bug.cgi?id=367991


Diffs
-----

  autotests/unit/engine/documenturldbtest.cpp 448821b 
  src/engine/documenturldb.cpp 5083e7a 
  src/engine/idutils.h cc7da9c 
  src/engine/writetransaction.cpp 3808970 

Diff: https://git.reviewboard.kde.org/r/128893/diff/


Testing
-------

Wrote test, valgrind shows error (or you get segfault, depending on luck) with old \
code, new one works.


Thanks,

Christoph Cullmann


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<div>Review request for KDE Frameworks and Boudhayan Gupta.</div>
<div>By Christoph Cullmann.</div>


<p style="color: grey;"><i>Updated Sept. 11, 2016, 4:40 p.m.</i></p>



<h1 style="color: #575012; font-size: 10pt; margin-top: 1.5em;">Changes</h1>
<table width="100%" bgcolor="#ffffff" cellspacing="0" cellpadding="10" style="border: \
1px solid #b8b5a0">  <tr>
  <td>
   <pre style="margin: 0; padding: 0; white-space: pre-wrap; white-space: \
-moz-pre-wrap; white-space: -pre-wrap; white-space: -o-pre-wrap; word-wrap: \
break-word;">Submitted with commit 6e5b41e88d92c90df8e54d99163cea08f17d0554 by \
Christoph Cullmann to branch master.</pre>  </td>
 </tr>
</table>







<div style="margin-top: 1.5em;">
 <b style="color: #575012; font-size: 10pt;">Repository: </b>
baloo
</div>


<h1 style="color: #575012; font-size: 10pt; margin-top: 1.5em;">Description </h1>
 <table width="100%" bgcolor="#ffffff" cellspacing="0" cellpadding="10" \
style="border: 1px solid #b8b5a0">  <tr>
  <td>
   <pre style="margin: 0; padding: 0; white-space: pre-wrap; white-space: \
-moz-pre-wrap; white-space: -pre-wrap; white-space: -o-pre-wrap; word-wrap: \
break-word;"><p style="padding: 0;text-rendering: inherit;margin: 0;line-height: \
inherit;white-space: inherit;">Old code was plain wrong:</p> <h2 style="font-size: \
100%;text-rendering: inherit;padding: 0;white-space: normal;margin: 0;line-height: \
inherit;">-        auto it = std::upper_bound(subDocs.begin(), subDocs.end(), \
id);</h2> <ul style="padding: 0;text-rendering: inherit;margin: 0 0 0 \
1em;line-height: inherit;white-space: normal;"> <li style="padding: 0;text-rendering: \
inherit;margin: 0;line-height: inherit;white-space: normal;">// Merge the id if it \
does not</li> <li style="padding: 0;text-rendering: inherit;margin: 0;line-height: \
inherit;white-space: normal;">auto prev = it - 1;</li> <li style="padding: \
0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: normal;">if \
(*prev != id) {</li> <li style="padding: 0;text-rendering: inherit;margin: \
0;line-height: inherit;white-space: normal;">subDocs.insert(it, id);</li> <li \
style="padding: 0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: \
normal;">}</li> </ul>
<p style="padding: 0;text-rendering: inherit;margin: 0;line-height: \
inherit;white-space: inherit;">=&gt; you deref begin()-1 in my test case</p> <p \
style="padding: 0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: \
inherit;">=&gt; BAM ;)</p> <p style="padding: 0;text-rendering: inherit;margin: \
0;line-height: inherit;white-space: inherit;">valgrind backtrace for old code (moved \
it to template method)</p> <p style="padding: 0;text-rendering: inherit;margin: \
0;line-height: inherit;white-space: inherit;">0 PASS   : \
DocumentUrlDBTest::testGetId() it == begin 1
==22283== Invalid read of size 8
==22283==    at 0x406F20: void Baloo::sortedIdInsert&lt;std::vector&lt;unsigned long \
long, std::allocator&lt;unsigned long long&gt; &gt;, unsigned long \
long&gt;(std::vector&lt;unsigned long long, std::allocator&lt;unsigned long long&gt; \
&gt;&amp;, unsigned long long const&amp;) (idutils.h:101) ==22283==    by 0x406965: \
DocumentUrlDBTest::testSortedIdInsert() (documenturldbtest.cpp:158) ==22283==    by \
0x404DD9: DocumentUrlDBTest::qt_static_metacall(QObject<em style="padding: \
0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: normal;">, \
QMetaObject::Call, int, void<strong style="padding: 0;text-rendering: inherit;margin: \
0;line-height: inherit;white-space: normal;">) (documenturldbtest.moc:99) ==22283==   \
by 0x57F90BD: QMetaMethod::invoke(QObject<em style="padding: 0;text-rendering: \
inherit;margin: 0;line-height: inherit;white-space: normal;">, Qt::ConnectionType, \
QGenericReturnArgument, QGenericArgument, QGenericArgument, QGenericArgument, \
QGenericArgument, QGenericArgument, QGenericArgument, QGenericArgument, \
QGenericArgument, QGenericArgument, QGenericArgument) const (in \
/usr/lib/libQt5Core.so.5.7.0) ==22283==    by 0x4E489D6: ??? (in \
/usr/lib/libQt5Test.so.5.7.0) ==22283==    by 0x4E49405: ??? (in \
/usr/lib/libQt5Test.so.5.7.0) ==22283==    by 0x4E49A51: ??? (in \
/usr/lib/libQt5Test.so.5.7.0) ==22283==    by 0x4E49F60: QTest::qExec(QObject</em>, \
int, char</strong>) (in /usr/lib/libQt5Test.so.5.7.0) ==22283==    by 0x404CF1: main \
(documenturldbtest.cpp:167) ==22283==  Address 0xbf25418 is 8 bytes before a block of \
size 8 alloc'd ==22283==    at 0x4C2A0FC: operator new(unsigned long) (in \
/usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so) ==22283==    by 0x40AF63: \
__gnu_cxx::new_allocator&lt;unsigned long long&gt;::allocate(unsigned long, void \
const</em>) (new_allocator.h:104) ==22283==    by 0x40AD46: \
std::allocator_traits&lt;std::allocator&lt;unsigned long long&gt; \
&gt;::allocate(std::allocator&lt;unsigned long long&gt;&amp;, unsigned long) \
(alloc_traits.h:416) ==22283==    by 0x40A171: std::_Vector_base&lt;unsigned long \
long, std::allocator&lt;unsigned long long&gt; &gt;::_M_allocate(unsigned long) \
(stl_vector.h:170) ==22283==    by 0x409151: void std::vector&lt;unsigned long long, \
std::allocator&lt;unsigned long long&gt; &gt;::_M_emplace_back_aux&lt;unsigned long \
long&gt;(unsigned long long&amp;&amp;) (vector.tcc:412) ==22283==    by 0x40886C: \
void std::vector&lt;unsigned long long, std::allocator&lt;unsigned long long&gt; \
&gt;::emplace_back&lt;unsigned long long&gt;(unsigned long long&amp;&amp;) \
(vector.tcc:101) ==22283==    by 0x406E55: std::vector&lt;unsigned long long, \
std::allocator&lt;unsigned long long&gt; &gt;::push_back(unsigned long \
long&amp;&amp;) (stl_vector.h:933) ==22283==    by 0x40694A: \
DocumentUrlDBTest::testSortedIdInsert() (documenturldbtest.cpp:155) ==22283==    by \
0x404DD9: DocumentUrlDBTest::qt_static_metacall(QObject<em style="padding: \
0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: normal;">, \
QMetaObject::Call, int, void</em><em style="padding: 0;text-rendering: \
inherit;margin: 0;line-height: inherit;white-space: normal;">) \
(documenturldbtest.moc:99) ==22283==    by 0x57F90BD: \
QMetaMethod::invoke(QObject</em>, Qt::ConnectionType, QGenericReturnArgument, \
QGenericArgument, QGenericArgument, QGenericArgument, QGenericArgument, \
QGenericArgument, QGenericArgument, QGenericArgument, QGenericArgument, \
QGenericArgument, QGenericArgument) const (in /usr/lib/libQt5Core.so.5.7.0) ==22283== \
by 0x4E489D6: ??? (in /usr/lib/libQt5Test.so.5.7.0) ==22283==    by 0x4E49405: ??? \
(in /usr/lib/libQt5Test.so.5.7.0) ==22283==</p>
<p style="padding: 0;text-rendering: inherit;margin: 0;line-height: \
inherit;white-space: inherit;">Bug report:</p> <p style="padding: 0;text-rendering: \
inherit;margin: 0;line-height: inherit;white-space: \
inherit;">https://bugs.kde.org/show_bug.cgi?id=367991</p></pre>  </td>
 </tr>
</table>


<h1 style="color: #575012; font-size: 10pt; margin-top: 1.5em;">Testing </h1>
<table width="100%" bgcolor="#ffffff" cellspacing="0" cellpadding="10" style="border: \
1px solid #b8b5a0">  <tr>
  <td>
   <pre style="margin: 0; padding: 0; white-space: pre-wrap; white-space: \
-moz-pre-wrap; white-space: -pre-wrap; white-space: -o-pre-wrap; word-wrap: \
break-word;"><p style="padding: 0;text-rendering: inherit;margin: 0;line-height: \
inherit;white-space: inherit;">Wrote test, valgrind shows error (or you get segfault, \
depending on luck) with old code, new one works.</p></pre>  </td>
 </tr>
</table>


<h1 style="color: #575012; font-size: 10pt; margin-top: 1.5em;">Diffs</b> </h1>
<ul style="margin-left: 3em; padding-left: 0;">

 <li>autotests/unit/engine/documenturldbtest.cpp <span style="color: \
grey">(448821b)</span></li>

 <li>src/engine/documenturldb.cpp <span style="color: grey">(5083e7a)</span></li>

 <li>src/engine/idutils.h <span style="color: grey">(cc7da9c)</span></li>

 <li>src/engine/writetransaction.cpp <span style="color: grey">(3808970)</span></li>

</ul>

<p><a href="https://git.reviewboard.kde.org/r/128893/diff/" style="margin-left: \
3em;">View Diff</a></p>






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