Parsing this file results in patchelf triggering an assertion:

patchelf: patchelf.cc:431: ElfFile<Elf64_Ehdr, Elf64_Phdr, Elf64_Shdr, unsigned long, unsigned long, Elf64_Dyn, Elf64_Sym, Elf64_Verneed, unsigned short>::ElfFile(FileContents) [Elf_Ehdr = Elf64_Ehdr, Elf_Phdr = Elf64_Phdr, Elf_Shdr = Elf64_Shdr, Elf_Addr = unsigned long, Elf_Off = unsigned long, Elf_Dyn = Elf64_Dyn, Elf_Sym = Elf64_Sym, Elf_Verneed = Elf64_Verneed, Elf_Versym = unsigned short]: Assertion `shstrtabIndex < shdrs.size()' failed.
Program received signal SIGABRT, Aborted.

Parsing this file results in patchelf triggering an assertion:

patchelf: patchelf.cc:384: void checkPointer(const FileContents &, void *, unsigned int): Assertion `q >= contents->data() && q + size <= contents->data() + contents->size()' failed.
Aborted (core dumped)

Parsing this file results in patchelf triggering an assertion:

patchelf: patchelf.cc:439: ElfFile<Elf64_Ehdr, Elf64_Phdr, Elf64_Shdr, unsigned long, unsigned long, Elf64_Dyn, Elf64_Sym, Elf64_Verneed, unsigned short>::ElfFile(FileContents) [Elf_Ehdr = Elf64_Ehdr, Elf_Phdr = Elf64_Phdr, Elf_Shdr = Elf64_Shdr, Elf_Addr = unsigned long, Elf_Off = unsigned long, Elf_Dyn = Elf64_Dyn, Elf_Sym = Elf64_Sym, Elf_Verneed = Elf64_Verneed, Elf_Versym = unsigned short]: Assertion `shstrtabSize > 0' failed.
Aborted (core dumped)

Parsing this file results in patchelf triggering an assertion:

patchelf: patchelf.cc:442: ElfFile<Elf64_Ehdr, Elf64_Phdr, Elf64_Shdr, unsigned long, unsigned long, Elf64_Dyn, Elf64_Sym, Elf64_Verneed, unsigned short>::ElfFile(FileContents) [Elf_Ehdr = Elf64_Ehdr, Elf_Phdr = Elf64_Phdr, Elf_Shdr = Elf64_Shdr, Elf_Addr = unsigned long, Elf_Off = unsigned long, Elf_Dyn = Elf64_Dyn, Elf_Sym = Elf64_Sym, Elf_Verneed = Elf64_Verneed, Elf_Versym = unsigned short]: Assertion `shstrtab[shstrtabSize - 1] == 0' failed.
Aborted (core dumped)

Parsing this file results in patchelf segfaulting at:

    at /nix/store/h31cy7jm6g7cfqbhc5pm4rf9c53i3qfb-gcc-9.3.0/include/c++/9.3.0/bits/char_traits.h:335
    at /nix/store/h31cy7jm6g7cfqbhc5pm4rf9c53i3qfb-gcc-9.3.0/include/c++/9.3.0/bits/basic_string.h:527
    this=0x7fffffff8028, fileContents=...) at patchelf.cc:449

... otherwise strlen() (in the std::string constructor) will be called
with an out-of-bounds pointer.

Parsing this file results in patchelf segfaulting at:

Program received signal SIGSEGV, Segmentation fault.
std::vector<Elf32_Phdr, std::allocator<Elf32_Phdr> >::_M_realloc_insert<Elf32_Phdr const&> (this=0x7fffffff80a8, __position=..., __args=...)
    at /nix/store/h31cy7jm6g7cfqbhc5pm4rf9c53i3qfb-gcc-9.3.0/include/c++/9.3.0/bits/vector.tcc:449
449		  _Alloc_traits::construct(this->_M_impl,
(gdb) bt
    at /nix/store/h31cy7jm6g7cfqbhc5pm4rf9c53i3qfb-gcc-9.3.0/include/c++/9.3.0/bits/vector.tcc:449
    at /nix/store/h31cy7jm6g7cfqbhc5pm4rf9c53i3qfb-gcc-9.3.0/include/c++/9.3.0/bits/stl_vector.h:1195
    this=0x7fffffff8088, fileContents=...) at patchelf.cc:421

sectionsByOldIndex was resized to hdr->e_shnum instead of
rdi(hdr->e_shnum). This omitted the endianness conversion and probably
only worked by accident, because the 16-bit LE->BE conversion results
in integers that are larger as long as there no more than 255 section
headers.

This would be a good usecase for std::transform, but I'm unsure
whether we want to bump requirements to build patchelf to C++ 2017.

This is similar to the earlier fix for phdr offsets, but the fuzzer
didn't find this.

Fuzzing fixes