Control: reassign 923720 libappstreamqt2/0.10.6-2
Control: affects 923720 plasma-discover
Control: fixed 923720 libappstreamqt2/0.11.3-1
Control: fixed 923720 plasma-discover/5.10.5-1
Control: tags 923720 + upstream fixed-upstream patch



Hello Everyone,
tried to get some more information from the backtrace.

I could not reproduce it but I think in this case method
AppStream::Pool::load got called with strerror being a null
pointer and for some reason the pool could not be loaded,
therefore line 77 was reached, trying to dereference strerror.

    (gdb) list AppStream::Pool::load(QString*)       
    71
    72      bool Pool::load(QString* strerror)
    73      {
    74          g_autoptr(GError) error = nullptr;
    75          bool ret = as_pool_load (d->m_pool, NULL, &error);
    76          if (!ret && error) {
    77              *strerror = QString::fromUtf8(error->message);      <<<<<<<
    78          }
    79          return ret;
    80      }
    81

This led to upstream fix in package appstream, available since 0.11.3: [1] [2]
Another fix was done in discover before, available since v5.10.5: [3] [4]

Therefore I assume this just affects Stretch.

Kind regards,
Bernhard


[1] https://github.com/ximion/appstream/pull/126
[2] 
https://github.com/ximion/appstream/commit/32f1445fd3f348598edd5e24e29ad3644c299639
[3] https://bugs.kde.org/show_bug.cgi?id=382916
[4] 
https://cgit.kde.org/discover.git/commit/?id=3a718124d45d60c49bb586e14d348f233178b34b
# Stretch amd64 qemu VM

apt update
apt dist-upgrade

apt install devscripts dpkg-dev systemd-coredump gdb xserver-xorg sddm 
plasma-desktop muon libappstreamqt2-dbgsym plasma-discover-dbgsym 
libglib2.0-0-dbg


systemctl start sddm



mkdir /tmp/source/appstream/orig -p
cd    /tmp/source/appstream/orig
apt source appstream
cd



###########

export DISPLAY=:0
# plasma-discover
gdb -q --args plasma-discover


set width 0
set pagination off
directory /tmp/source/appstream/orig/appstream-0.10.6
display/i $pc
break AppStream::Pool::load
y
run
disa 1.1
disa 1.3
disa 1.4
cont
bt



############


benutzer@debian:~$ gdb -q --args plasma-discover
Reading symbols from plasma-discover...Reading symbols from 
/usr/lib/debug/.build-id/8e/af6f71ec2d372a44c646c9eb0311f4bb45dd50.debug...done.
done.
(gdb) set width 0
(gdb) set pagination off
(gdb) directory /tmp/source/appstream/orig/appstream-0.10.6
Source directories searched: 
/tmp/source/appstream/orig/appstream-0.10.6:$cdir:$cwd
(gdb) display/i $pc
1: x/i $pc
<error: No registers.>
(gdb) break AppStream::Pool::load
Function "AppStream::Pool::load" not defined.
Make breakpoint pending on future shared library load? (y or [n]) y
Breakpoint 1 (AppStream::Pool::load) pending.
(gdb) run
Starting program: /usr/bin/plasma-discover 
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
[New Thread 0x7fffe66c2700 (LWP 2475)]
[New Thread 0x7fffe5a39700 (LWP 2476)]
[New Thread 0x7fffe5238700 (LWP 2478)]
[New Thread 0x7fffd278d700 (LWP 2479)]
[New Thread 0x7fffd1f8c700 (LWP 2480)]
[New Thread 0x7fffd178b700 (LWP 2481)]
[New Thread 0x7fffd0f8a700 (LWP 2482)]
[New Thread 0x7fffd0789700 (LWP 2483)]
[New Thread 0x7fffcff88700 (LWP 2484)]
[New Thread 0x7fffcf787700 (LWP 2485)]
[New Thread 0x7fffcef86700 (LWP 2486)]
[New Thread 0x7fffce01e700 (LWP 2487)]
[New Thread 0x7fffcd81c700 (LWP 2488)]
file:///usr/lib/x86_64-linux-gnu/qt5/qml/org/kde/kirigami/GlobalDrawer.qml:213:9:
 QML Flickable: Binding loop detected for property "contentWidth"
invalid kns backend! "" because: "Couldn't find knsrc file: comic.knsrc"

Thread 1 "plasma-discover" hit Breakpoint 1, 0x00007fffc77e3cd0 in 
AppStream::Pool::load()@plt () from 
/usr/lib/x86_64-linux-gnu/qt5/plugins/discover/packagekit-backend.so
1: x/i $pc
=> 0x7fffc77e3cd0 <_ZN9AppStream4Pool4loadEv@plt>:      jmpq   *0x2305ca(%rip)  
      # 0x7fffc7a142a0
(gdb) disa 1.1
(gdb) disa 1.3
(gdb) disa 1.4
(gdb) cont
Continuing.

Thread 1 "plasma-discover" hit Breakpoint 1, AppStream::Pool::load 
(this=this@entry=0x555555dcd3c8, strerror=strerror@entry=0x0) at 
./qt/pool.cpp:73
73      {
1: x/i $pc
=> 0x7fffc738d020 <AppStream::Pool::load(QString*)>:    push   %r12
(gdb) next
75          bool ret = as_pool_load (d->m_pool, NULL, &error);
1: x/i $pc
=> 0x7fffc738d038 <AppStream::Pool::load(QString*)+24>: mov    0x10(%rdi),%rax
(gdb) 
74          g_autoptr(GError) error = nullptr;
1: x/i $pc
=> 0x7fffc738d03c <AppStream::Pool::load(QString*)+28>: movq   $0x0,0x10(%rsp)
(gdb) 
75          bool ret = as_pool_load (d->m_pool, NULL, &error);
1: x/i $pc
=> 0x7fffc738d045 <AppStream::Pool::load(QString*)+37>: test   %rax,%rax
(gdb) 
76          if (!ret && error) {
1: x/i $pc
=> 0x7fffc738d065 <AppStream::Pool::load(QString*)+69>: jne    0x7fffc738d0b8 
<AppStream::Pool::load(QString*)+152>

(gdb) bt
#0  0x00007fffc738d065 in AppStream::Pool::load(QString*) 
(this=this@entry=0x555555dcd3c8, strerror=strerror@entry=0x0) at 
./qt/pool.cpp:76
#1  0x00007fffc738d147 in AppStream::Pool::load() 
(this=this@entry=0x555555dcd3c8) at ./qt/pool.cpp:69
#2  0x00007fffc77ea7f3 in PackageKitBackend::PackageKitBackend(QObject*) 
(this=0x555555dcd3b0, parent=<optimized out>) at 
./libdiscover/backends/PackageKitBackend/PackageKitBackend.cpp:67
#3  0x00007fffc77f0c61 in PackageKitBackendFactory::newInstance(QObject*) const 
(this=this@entry=0x555555dd2260, parent=0x5555558d9cc0) at 
./libdiscover/backends/PackageKitBackend/PackageKitBackend.cpp:52
#4  0x00007ffff73b0085 in DiscoverBackendsFactory::backendForFile(QString 
const&, QString const&) const (this=this@entry=0x7fffffffdddf, path=..., 
name=...) at ./libdiscover/DiscoverBackendsFactory.cpp:64
#5  0x00007ffff73b08b0 in DiscoverBackendsFactory::backend(QString const&) 
const (this=0x7fffffffdddf, name=...) at 
./libdiscover/DiscoverBackendsFactory.cpp:46
#6  0x00007ffff73b0a88 in DiscoverBackendsFactory::allBackends() const 
(this=this@entry=0x7fffffffdddf) at 
./libdiscover/DiscoverBackendsFactory.cpp:102
#7  0x00007ffff73a078a in ResourcesModel::registerAllBackends() 
(this=0x5555558d9cc0) at ./libdiscover/resources/ResourcesModel.cpp:404
#8  0x00007ffff73b8105 in ResourcesModel::qt_static_metacall(QObject*, 
QMetaObject::Call, int, void**) (_o=<optimized out>, _c=<optimized out>, 
_id=<optimized out>, _a=<optimized out>) at 
./obj-x86_64-linux-gnu/libdiscover/DiscoverCommon_automoc.dir/moc_ResourcesModel_NCTDQYLM2TZVLQ.cpp:177
#9  0x00007ffff52f9769 in QObject::event(QEvent*) () at 
/usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#10 0x00007ffff6240b8c in QApplicationPrivate::notify_helper(QObject*, QEvent*) 
() at /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5
#11 0x00007ffff6248351 in QApplication::notify(QObject*, QEvent*) () at 
/usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5
#12 0x00007ffff52ccd30 in QCoreApplication::notifyInternal2(QObject*, QEvent*) 
() at /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#13 0x00007ffff52cf4cd in QCoreApplicationPrivate::sendPostedEvents(QObject*, 
int, QThreadData*) () at /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#14 0x00007ffff5320dc3 in  () at /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#15 0x00007fffeff117f7 in g_main_dispatch (context=0x7fffe00016f0) at 
././glib/gmain.c:3203
#16 0x00007fffeff117f7 in g_main_context_dispatch 
(context=context@entry=0x7fffe00016f0) at ././glib/gmain.c:3856
#17 0x00007fffeff11a60 in g_main_context_iterate 
(context=context@entry=0x7fffe00016f0, block=block@entry=1, 
dispatch=dispatch@entry=1, self=<optimized out>) at ././glib/gmain.c:3929
#18 0x00007fffeff11b0c in g_main_context_iteration (context=0x7fffe00016f0, 
may_block=1) at ././glib/gmain.c:3990
#19 0x00007ffff53211cf in 
QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () 
at /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#20 0x00007ffff52cad1a in 
QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () at 
/usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#21 0x00007ffff52d346c in QCoreApplication::exec() () at 
/usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#22 0x000055555555ec02 in main(int, char**) (argc=<optimized out>, 
argv=<optimized out>) at ./discover/main.cpp:148

(gdb) list AppStream::Pool::load(QString*)       
71
72      bool Pool::load(QString* strerror)
73      {
74          g_autoptr(GError) error = nullptr;
75          bool ret = as_pool_load (d->m_pool, NULL, &error);
76          if (!ret && error) {
77              *strerror = QString::fromUtf8(error->message);
78          }
79          return ret;
80      }
81

(gdb) print strerror
$1 = (QString *) 0x0

(gdb) disassemble  AppStream::Pool::load(QString*)
Dump of assembler code for function AppStream::Pool::load(QString*):
   0x00007fffc738d020 <+0>:     push   %r12
   0x00007fffc738d022 <+2>:     push   %rbp
   0x00007fffc738d023 <+3>:     push   %rbx
   0x00007fffc738d024 <+4>:     sub    $0x20,%rsp
   0x00007fffc738d028 <+8>:     mov    %fs:0x28,%rax
   0x00007fffc738d031 <+17>:    mov    %rax,0x18(%rsp)
   0x00007fffc738d036 <+22>:    xor    %eax,%eax
   0x00007fffc738d038 <+24>:    mov    0x10(%rdi),%rax
   0x00007fffc738d03c <+28>:    movq   $0x0,0x10(%rsp)
   0x00007fffc738d045 <+37>:    test   %rax,%rax
   0x00007fffc738d048 <+40>:    je     0x7fffc738d102 
<AppStream::Pool::load(QString*)+226>
   0x00007fffc738d04e <+46>:    mov    (%rax),%rdi
   0x00007fffc738d051 <+49>:    lea    0x10(%rsp),%rdx
   0x00007fffc738d056 <+54>:    mov    %rsi,%rbp
   0x00007fffc738d059 <+57>:    xor    %esi,%esi
   0x00007fffc738d05b <+59>:    callq  0x7fffc7385920 <as_pool_load@plt>
   0x00007fffc738d060 <+64>:    test   %eax,%eax
   0x00007fffc738d062 <+66>:    setne  %bl
=> 0x00007fffc738d065 <+69>:    jne    0x7fffc738d0b8 
<AppStream::Pool::load(QString*)+152>
   0x00007fffc738d067 <+71>:    mov    0x10(%rsp),%rax
   0x00007fffc738d06c <+76>:    test   %rax,%rax
   0x00007fffc738d06f <+79>:    je     0x7fffc738d0c7 
<AppStream::Pool::load(QString*)+167>
   0x00007fffc738d071 <+81>:    mov    0x8(%rax),%r12
   0x00007fffc738d075 <+85>:    mov    $0xffffffff,%edx
   0x00007fffc738d07a <+90>:    test   %r12,%r12
   0x00007fffc738d07d <+93>:    je     0x7fffc738d089 
<AppStream::Pool::load(QString*)+105>
   0x00007fffc738d07f <+95>:    mov    %r12,%rdi
   0x00007fffc738d082 <+98>:    callq  0x7fffc73858e0 <strlen@plt>
   0x00007fffc738d087 <+103>:   mov    %eax,%edx
   0x00007fffc738d089 <+105>:   mov    %rsp,%rdi
   0x00007fffc738d08c <+108>:   mov    %r12,%rsi
   0x00007fffc738d08f <+111>:   callq  0x7fffc7386150 
<_ZN7QString15fromUtf8_helperEPKci@plt>
   0x00007fffc738d094 <+116>:   mov    0x0(%rbp),%rax                           
                        <<<<<<<<<<< Crash from message #5
   0x00007fffc738d098 <+120>:   mov    (%rsp),%rdx
   0x00007fffc738d09c <+124>:   mov    %rax,(%rsp)
   0x00007fffc738d0a0 <+128>:   mov    %rdx,0x0(%rbp)
   0x00007fffc738d0a4 <+132>:   mov    (%rax),%edx
   0x00007fffc738d0a6 <+134>:   test   %edx,%edx
   0x00007fffc738d0a8 <+136>:   je     0x7fffc738d0e8 
<AppStream::Pool::load(QString*)+200>
   0x00007fffc738d0aa <+138>:   cmp    $0xffffffff,%edx
   0x00007fffc738d0ad <+141>:   je     0x7fffc738d0b8 
<AppStream::Pool::load(QString*)+152>
   0x00007fffc738d0af <+143>:   lock subl $0x1,(%rax)
   0x00007fffc738d0b3 <+147>:   je     0x7fffc738d0e8 
<AppStream::Pool::load(QString*)+200>
   0x00007fffc738d0b5 <+149>:   nopl   (%rax)
   0x00007fffc738d0b8 <+152>:   mov    0x10(%rsp),%rdi
   0x00007fffc738d0bd <+157>:   test   %rdi,%rdi
   0x00007fffc738d0c0 <+160>:   je     0x7fffc738d0c7 
<AppStream::Pool::load(QString*)+167>
   0x00007fffc738d0c2 <+162>:   callq  0x7fffc7385900 <g_error_free@plt>
   0x00007fffc738d0c7 <+167>:   mov    0x18(%rsp),%rcx
   0x00007fffc738d0cc <+172>:   xor    %fs:0x28,%rcx
   0x00007fffc738d0d5 <+181>:   mov    %ebx,%eax
   0x00007fffc738d0d7 <+183>:   jne    0x7fffc738d0fd 
<AppStream::Pool::load(QString*)+221>
   0x00007fffc738d0d9 <+185>:   add    $0x20,%rsp
   0x00007fffc738d0dd <+189>:   pop    %rbx
   0x00007fffc738d0de <+190>:   pop    %rbp
   0x00007fffc738d0df <+191>:   pop    %r12
   0x00007fffc738d0e1 <+193>:   retq   
   0x00007fffc738d0e2 <+194>:   nopw   0x0(%rax,%rax,1)
   0x00007fffc738d0e8 <+200>:   mov    (%rsp),%rdi
   0x00007fffc738d0ec <+204>:   mov    $0x8,%edx
   0x00007fffc738d0f1 <+209>:   mov    $0x2,%esi
   0x00007fffc738d0f6 <+214>:   callq  0x7fffc73859b0 
<_ZN10QArrayData10deallocateEPS_mm@plt>
   0x00007fffc738d0fb <+219>:   jmp    0x7fffc738d0b8 
<AppStream::Pool::load(QString*)+152>
   0x00007fffc738d0fd <+221>:   callq  0x7fffc73857e0 <__stack_chk_fail@plt>
   0x00007fffc738d102 <+226>:   lea    0x65ff(%rip),%rsi        # 0x7fffc7393708
   0x00007fffc738d109 <+233>:   lea    0x664d(%rip),%rdi        # 0x7fffc739375d
   0x00007fffc738d110 <+240>:   mov    $0x76,%edx
   0x00007fffc738d115 <+245>:   callq  0x7fffc7385e70 <_Z9qt_assertPKcS0_i@plt>
   0x00007fffc738d11a <+250>:   mov    0x10(%rsp),%rdi
   0x00007fffc738d11f <+255>:   mov    %rax,%rbx
   0x00007fffc738d122 <+258>:   test   %rdi,%rdi
   0x00007fffc738d125 <+261>:   je     0x7fffc738d12c 
<AppStream::Pool::load(QString*)+268>
   0x00007fffc738d127 <+263>:   callq  0x7fffc7385900 <g_error_free@plt>
   0x00007fffc738d12c <+268>:   mov    %rbx,%rdi
   0x00007fffc738d12f <+271>:   callq  0x7fffc7385ba0 <_Unwind_Resume@plt>
End of assembler dump.


#########

https://github.com/ximion/appstream/pull/126
https://github.com/ximion/appstream/commit/32f1445fd3f348598edd5e24e29ad3644c299639

https://bugs.kde.org/show_bug.cgi?id=382916
https://cgit.kde.org/discover.git/commit/?id=3a718124d45d60c49bb586e14d348f233178b34b

#########

Fix in appstream released in 0.11.3:
https://github.com/ximion/appstream/commit/35e0f922df6ce01c4d4580be6b893710e734562d

Fix in discover released in v5.10.5
https://cgit.kde.org/discover.git/log/?ofs=1370

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