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
#4 0x0000000000404774 in patchElf () at patchelf.cc:1848
#5 0x000000000040551c in mainWrapped (argc=3, argv=0x7fffffffc148) at patchelf.cc:2003
#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.
When loading the executable on MIPS, the dynamic loader looks for MIPS
ABI flags using PT_MIPS_ABIFLAGS header. The flags themselves are stored
in the .MIPS.abiflags section, so the header must be updated when the
section is moved.
Here we also import PT_MIPS_ABIFLAGS definition from glibc commit
0bd956720c457ff054325b48f26ac7c91cb060e8.
Closes: #82
Signed-off-by: Ivan A. Melnikov <iv@altlinux.org>
`patchelf --set-rpath` corrupted executables on mips32el: the dynamic
liker crushed with Segmentation fault when loading any executable with
RPATH added that way.
The problem was around the MIPS-specific mechanism of setting up the
debug map pointer. When DT_MIPS_RLD_MAP_REL entry in the dynamic section
is present, it holds the relative address of __RLD_MAP -- an offset
relative to this dynamic section entry. Dynamic linker puts the
pointer to the `r_debug` structure there.
When patchelf updates the executable RPATH, it moves the .dynamic
section both in the binary and in memory, while __RLD_MAP is not moved
in memory, since it belongs to special .rld_map section that has type
PROGBITS. So, the offset stored in DT_MIPS_RLD_MAP_REL entry is not
valid anymore and should be updated.
This commit adds the necessary update.
In the corner case when DT_MIPS_RLD_MAP_REL is present, but
.rld_map section is not, the dynamic loader writes the debug
pointer to some arbitrary bytes in memory. To avoid crushes
on otherwise "working" binaries, we set offset to zero
so that the dynamic loader would just overwrite the dynamic
section.
Here we also import DT_MIPS_RLD_MAP_REL definition in elf.h form
glibc commit a2057c984e4314c3740f04cf54e36c824e4c8f32.
Refs: #82
Signed-off-by: Ivan A. Melnikov <iv@altlinux.org>
