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alt_saver: some bugfixes for user-reported issues #46

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Merged
merged 2 commits into from
Apr 21, 2024
Merged

alt_saver: some bugfixes for user-reported issues #46

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3aa93e3
alt_saver: port fix for segment shifting breaking some systems
Bo98 Apr 8, 2024
627ab8c
alt_saver: fix crash on invalid symbol section
Bo98 Apr 8, 2024
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13 changes: 7 additions & 6 deletions lib/patchelf/alt_saver.rb
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Original file line number Diff line number Diff line change
Expand Up @@ -451,10 +451,10 @@ def rewrite_headers(phdr_address)

begin
new_index = new_section_idx(old_shndx)
next unless new_index
rescue ArgumentError
Logger.warn "entry #{entry} in symbol table refers to a non existing section, skipping"
end
next unless new_index

sym[pack[:st_shndx]] = new_index

Expand Down Expand Up @@ -561,11 +561,12 @@ def rewrite_sections_executable
if needed_space > start_offset
needed_space += seg_num_bytes # new load segment is required

needed_pages = Helper.alignup(needed_space - start_offset, page_size) / page_size
extra_bytes = needed_space - start_offset
needed_pages = Helper.alignup(extra_bytes, page_size) / page_size
Logger.debug "needed pages is #{needed_pages}"
raise PatchError, 'virtual address space underrun' if needed_pages * page_size > first_page

shift_file(needed_pages, start_offset)
shift_file(needed_pages, start_offset, extra_bytes)

first_page -= needed_pages * page_size
start_offset += needed_pages * page_size
Expand Down Expand Up @@ -776,7 +777,7 @@ def shift_segments(shift, start_offset)
end
# rubocop:enable Metrics/PerceivedComplexity

def shift_file(extra_pages, start_offset)
def shift_file(extra_pages, start_offset, extra_bytes)
raise PatchError, "start_offset(#{start_offset}) < ehdr.num_bytes" if start_offset < ehdr.num_bytes

oldsz = @buffer.size
Expand All @@ -799,8 +800,8 @@ def shift_file(extra_pages, start_offset)
p_offset: split_phdr.p_offset - split_shift - shift,
p_vaddr: split_phdr.p_vaddr - split_shift - shift,
p_paddr: split_phdr.p_paddr - split_shift - shift,
p_filesz: split_shift + shift,
p_memsz: split_shift + shift,
p_filesz: split_shift + extra_bytes,
p_memsz: split_shift + extra_bytes,
p_flags: ELFTools::Constants::PF_R | ELFTools::Constants::PF_W,
p_align: page_size
)
Expand Down