**System Information**
Operating system: Windows-10-10.0.19041-SP0 64 Bits
Graphics card: GeForce GTX 1080/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 446.14
**Blender Version**
Broken: version: 3.0.0 Alpha, branch: master, commit date: 2021-06-18 15:20, hash: `rBd52b7dbe2695`
Worked: Not sure. The relevant code hasn't changed since late last year.
**Short description of error**
With AddressSanitizer enabled, the attached .blend file causes a crash when extruding with the "Dissolve Orthogonal Edges" option enabled.
Also, see the comment below for another case that causes a crash in release builds.
**Exact steps for others to reproduce the error**
1. Open the attached file
2. //Select the "Bad" vertex group// -- the vertices are already selected, but when the file is loaded, the edge doesn't get included due to a separate bug)
3. Extrude (E) anywhere
4. In the //Extrude Region and Move// panel, enable //Dissolve Orthogonal Edges//
5. AddressSanitizer causes a crash
{F10180596}
This specific case seems benign if AddressSanitizer is not present.
The geometry data is just an edge extruded on top of itself. `data.validate()` doesn't complain about it.
```
SUMMARY: AddressSanitizer: heap-buffer-overflow D:\blender-git\blender\source\blender\bmesh\operators\bmo_extrude.c:585 in bmo_extrude_face_region_exec
Shadow bytes around the buggy address:
0x038557f7d5a0: fa fa fd fd fa fa fd fd fa fa fd fd fa fa fd fd
0x038557f7d5b0: fa fa fd fd fa fa fd fd fa fa fd fd fa fa fd fd
0x038557f7d5c0: fa fa fd fd fa fa 00 00 fa fa 00 00 fa fa 00 00
0x038557f7d5d0: fa fa 00 00 fa fa 00 04 fa fa fd fd fa fa 00 00
0x038557f7d5e0: fa fa 00 00 fa fa 00 00 fa fa 00 00 fa fa 00 00
=>0x038557f7d5f0: fa fa 00 00[fa]fa fd fa fa fa fd fa fa fa 04 fa
0x038557f7d600: fa fa 04 fa fa fa 01 fa fa fa 01 fa fa fa 00 fa
0x038557f7d610: fa fa 04 fa fa fa 00 04 fa fa 04 fa fa fa 04 fa
0x038557f7d620: fa fa 00 fa fa fa 00 fa fa fa 04 fa fa fa 00 fa
0x038557f7d630: fa fa 00 fa fa fa 04 fa fa fa 00 fa fa fa 00 00
0x038557f7d640: fa fa 00 fa fa fa 04 fa fa fa 00 fa fa fa 00 04
```