Add support for dynamic symbols when DYNAMIC segment is missing #2
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nsavoire
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nsavoire
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Pull Request Overview
This PR enables parsing of dynamic symbols and their string table from section headers when the PT_DYNAMIC segment is absent, falling back to PT_DYNAMIC only if needed.
- Initialize
dynsymsanddynstrtabearlier to a known default state - Add parsing of
.dynsym/.dynstrviaSHT_DYNSYMsection - Introduce fallback logic: use DYNAMIC segment only if section-based tables are empty
Comments suppressed due to low confidence (1)
symbolic-debuginfo/src/elf.rs:245
- Add unit tests to verify the new fallback behavior: parsing
.dynsym/.dynstrsections in the absence of a PT_DYNAMIC segment, ensuring correct symbol resolution for debug-only ELF files.
if obj.dynstrtab.len() == 0 {
buranmert
approved these changes
May 21, 2025
If dynamic symbols cannot be parsed from the DYNAMIC segment, try to parse them from the section headers.
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Some open questions:
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Pull Request Overview
This PR adds a fallback mechanism to locate and parse dynamic symbols using section headers when the DYNAMIC segment is missing, targeting debug information files produced by objcopy.
- Added fallback logic in elf.rs to iterate over section headers and parse .dynsym and .dynstr sections when obj.dynsyms is empty
- Adjusted data parsing to support files without a DYNAMIC segment
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| )); | ||
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| obj.dynstrtab = return_partial_on_err!(get_strtab(&obj.section_headers, shdr.sh_link as usize)); |
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After successfully parsing the dynamic symbol table and string table, consider breaking out of the loop to prevent potential overwrites if multiple SHT_DYNSYM sections are present.
Suggested change
| obj.dynstrtab = return_partial_on_err!(get_strtab(&obj.section_headers, shdr.sh_link as usize)); | |
| obj.dynstrtab = return_partial_on_err!(get_strtab(&obj.section_headers, shdr.sh_link as usize)); | |
| break; |
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Symbolic currently relies on DYNAMIC segment to locate and parse dynamic symbols.
This works for full executables but not for debug information extracted with
objcopy --only-keep-debugwhere we have added back dynamic symbol sections (.dynsym/.dynstr), because in those files, DYNAMIC segment is stripped.This PR adds the ability to use section headers to locate
.dynsymand.dynstrsections when DYNAMIC segment cannot be used.