Local patches for patchelf 0.9 #2
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They all have that page size, and the host-detected one might be different.
… and not overwriting NOBITS entries.
The current approach to changing sections in ET_DYN executables is to move the INTERP section to the end of the file. +This means changing PT_PHDR to add an extra PT_LOAD section so that the new section is mmaped into memory by the elf loader in the kernel. In order to extend PHDR, this means moving it to the end of the file. Its documented in BUGS there is a kernel 'bug' which means that if you have holes in memory between the base load address and the PT_LOAD segment that contains PHDR, it will pass an incorrect PHDR address to ld.so and fail to load the binary, segfaulting. To avoid this, the code currently inserts space into the binary to ensure that when loaded into memory there are no holes between the PT_LOAD sections. This inflates the binaries by many MBs in some cases. Whilst we could make them sparse, there is a second issue which is that strip can fail to process these binaries: $ strip fixincl Not enough room for program headers, try linking with -N [.note.ABI-tag]: Bad value This turns out to be due to libbfd not liking the relocated PHDR section either (NixOS#10). Instead this patch implements a different approach, leaving PHDR where it is but extending it in place to allow addition of a new PT_LOAD section. This overwrites sections in the binary but those get moved to the end of the file in the new PT_LOAD section. This is based on patches linked from the above github issue, however whilst the idea was good, the implementation wasn't correct and they've been rewritten here. Signed-off-by: Richard Purdie <[email protected]> (cherry picked from commit c4deb5e) Signed-off-by: Claudio Matsuoka <[email protected]>
Signed-off-by: Claudio Matsuoka <[email protected]>
startPage is adjusted unconditionally for all executables. This results in incorrect addresses assigned to INTERP and LOAD program headers, which breaks patched executable. Adjusting startPage variable only when startOffset > startPage should fix this. This change is related to the issue NixOS#10 Signed-off-by: Ed Bartosh <[email protected]>
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Otherwise, patchelf segfaults when it encounters DT_NEEDED in the read
garbage. Corresponding backtrace is:
#0 0x00007ffff7c275f7 in __strlen_avx2 () from /nix/store/cvr0kjg2q7z2wwhjblx6c73rv422k8cm-glibc-2.33-47/lib/libc.so.6
#1 0x00007ffff7f2d448 in std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::basic_string(char const*, std::allocator<char> const&) () from /nix/store/lg104nh0szci8slz5z6494m457jm5y3p-gcc-10.3.0-lib/lib/libstdc++.so.6
#2 0x000000000040fe0f in ElfFile<Elf64_Ehdr, Elf64_Phdr, Elf64_Shdr, unsigned long, unsigned long, Elf64_Dyn, Elf64_Sym, Elf64_Verneed, unsigned short>::modifyRPath (this=0x7fffffffbaa0,
op=ElfFile<Elf64_Ehdr, Elf64_Phdr, Elf64_Shdr, unsigned long, unsigned long, Elf64_Dyn, Elf64_Sym, Elf64_Verneed, unsigned short>::rpPrint, allowedRpathPrefixes=std::vector of length 0, capacity 0, newRPath="") at patchelf.cc:1351
#3 0x00000000004061c3 in patchElf2<ElfFile<Elf64_Ehdr, Elf64_Phdr, Elf64_Shdr, unsigned long, unsigned long, Elf64_Dyn, Elf64_Sym, Elf64_Verneed, unsigned short> > (elfFile=..., fileContents=std::shared_ptr<std::vector<unsigned char, std::allocator<unsigned char> >> (use count 3, weak count 0) = {...},
fileName="libsystemd.debug") at patchelf.cc:1805
NixOS#4 0x0000000000404774 in patchElf () at patchelf.cc:1848
NixOS#5 0x000000000040551c in mainWrapped (argc=3, argv=0x7fffffffc148) at patchelf.cc:2003
NixOS#6 0x0000000000405913 in main (argc=3, argv=0x7fffffffc148) at patchelf.cc:2011
NOBIT sections are included in the section headers table but occupy no
actual space in the file. .dynamic sections of this types are created,
for example, by `strip --only-keep-debug`.
I'm not sure whether calling error() would be more appropriate than
ignoring this situation with debug/return. I chose ignoring it,
because error() caused autoPatchelfHook to fail with my package. Also
the rest of modifyRPath method simply calls debug/return in similar
situations.
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Includes the following patches:
stripNixOS/patchelf#10)cannot find sectionNixOS/patchelf#66 by ignoring the first section header when sorting