Tags · xqqv5/ImHex

nightly

Fix nullptr deref when opening ImHex without a provider on frame 1 (W…

…erWolv#2718)

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### Problem description
Commit
WerWolv@f813656
introduced a nullptr dereference that happens on the first frame of a
provider being opened.

```
[12:03:47] [INFO]  [main | Main]                Switching to workspace 'Default'
Process 89715 stopped
* thread WerWolv#1, name = 'ImHex 🔍', stop reason = signal SIGSEGV: address not mapped to object (fault address=0x0)
    frame #0: 0x00007fffcdd43958 ui.hexpluglib`::drawEditor() at hex_editor.cpp:648:46
   645 	                ImGui::TableSetupScrollFreeze(0, 2);
   646 	
   647 	                // Row address column
-> 648 	                u64 maxAddress = m_provider->getActualSize();
    	                                             ^
   649 	                if (maxAddress > 0)
   650 	                    maxAddress--;
   651 	                if ((m_scrollPosition + m_visibleRowCount) * bytesPerRow < maxAddress)
(lldb) bt
* thread WerWolv#1, name = 'ImHex 🔍', stop reason = signal SIGSEGV: address not mapped to object (fault address=0x0)
  * frame #0: 0x00007fffcdd43958 ui.hexpluglib`::drawEditor() at hex_editor.cpp:648:46
    frame WerWolv#1: 0x00007fffcdd4954b ui.hexpluglib`::draw() at hex_editor.cpp:1409:15
    frame WerWolv#2: 0x00007fffdc01eb21 diffing.hexplug`::drawDiffColumn() at view_diff.cpp:64:30
    frame WerWolv#3: 0x00007fffdc01d56d diffing.hexplug`::drawContent() at view_diff.cpp:271:28
    frame WerWolv#4: 0x00007ffff7af7413 libimhex.so.1.39.0.WIP`::draw() at view.cpp:201:23
    frame WerWolv#5: 0x0000555555593e7d imhex`::frame() at window.cpp:759:23
    frame WerWolv#6: 0x000055555559237d imhex`hex::Window::fullFrame() at window.cpp:200:19
    frame WerWolv#7: 0x00005555555948b5 imhex`::loop() at window.cpp:297:19
    frame WerWolv#8: 0x00005555555c211c imhex`::runImHex() at desktop.cpp:54:28
    frame WerWolv#9: 0x00005555555836a6 imhex`main at main.cpp:73:12
    frame WerWolv#10: 0x00007ffff682f43b libc.so.6`___lldb_unnamed_symbol_2b3c0 + 123
    frame WerWolv#11: 0x00007ffff682f4eb libc.so.6`__libc_start_main + 139
    frame WerWolv#12: 0x00005555555831d5 imhex`_start + 37
```

### Implementation description
If nullptr check guard.