pkg/cover/backend: found unexpected tag PartialUnit on top level about syzkaller HOT 2 OPEN

Hi Jiri,

Thanks for the report.
How can we reproduce such kernel build with DW_TAG_partial_unit?
Do you know how to get them in a unit test? Some special compiler flags?
The DWARF excerpt suggests that DW_TAG_partial_unit contains the same subtags as DW_TAG_compile_unit, if so doing:

   if ent.Tag != dwarf.TagCompileUnit && ent.Tag != dwarf.TagPartialUnit { 

may work?

from syzkaller.

Hi,

I was using our (openSUSE) kernel rpm tooling to build a "syzkaller" kernel (easy for me to build, transfer and install). The tooling uses dwz to compress the dwarf info. I believe it's exactly the source of these partial units.

Even with the if you propose above, there is TAG_BaseType at the root. And I suppose many more.

Now I switched to classic make && make modules_install model and have no issue.

Apart from this issue, it was pretty cumbersome, because syzkaller does not support separate *.debug files with .debug_info sections (using .gnu_debuglink). So I had to eu-unstrip all interesting binaries to work this around.

Further, the paths were hell (like sources referenced in .debug_* sections as /usr/src/debug/...).

I am not sure anyone wants to invest time to fix all this.

from syzkaller.