[PATCH] elf: Keep SHT_NULL sections in executable and shared library

[Jan Beulich]

On 29.06.2025 09:56, H.J. Lu wrote:
> Some linkers generate SHT_NULL sections in executable and shared
> library:
> 
> Section Headers:
>   [Nr] Name              Type             Address           Offset
>        Size              EntSize          Flags  Link  Info  Align
>   [ 0]                   NULL             0000000000000000  00000000
>        0000000000000000  0000000000000000   A       0     0     0
>   [ 1] .phdr             NULL             0000000000000040  00000040
>        0000000000000000  0000000000000000   A       0     0     0
>   [ 2] .shdr             NULL             0000000000000238  00000238
>        0000000000000000  0000000000000000   A       0     0     0
>   [ 3] .note.gnu.pr[...] NOTE             0000000000000938  00000938
> ...
>  Section to Segment mapping:
>   Segment Sections...
>    00
>    01     .phdr .shdr .note.gnu.property .gnu.hash .dynsym .dynstr .gnu.version
> .gnu.version_r .rela.dyn .rodata .eh_frame_hdr .eh_frame
> 
> We must keep SHT_NULL sections in executable and shared library if there
> is a non-empty SHT_DYNSYM section since removing them may change section
> indexes in SHT_DYNSYM section.

Question: Why would it every be okay to remove / re-use them? IOW
shouldn't we unconditionally keep them?

Jan