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Kernels before 5.18 (e.g. RHEL 9's 5.14) compute AT_PHDR as load_bias + e_phoff and ignore PT_PHDR. When the file has to grow, patchelf moves the program headers into a new PT_LOAD segment. If the new segment's file offset differs from its virtual address, ld.so is handed a bogus phdr pointer and the binary segfaults at startup. This happens in two cases: - Non-alloc sections (.symtab, .strtab, ...) sit after the last segment, so the new segment's file offset is larger than its virtual address. Make the virtual address equal the file offset. - Executables with a large .bss (e.g. Qt's lupdate) get the new PT_LOAD placed at a virtual address above its file offset. Pad the file so vaddr == file offset for executables. grow-file.sh now passes. Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
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Kernels before 5.18 (e.g. RHEL 9's 5.14) compute AT_PHDR as load_bias + e_phoff and ignore PT_PHDR. When the file has to grow, patchelf moves the program headers into a new PT_LOAD segment. If the new segment's file offset differs from its virtual address, ld.so is handed a bogus phdr pointer and the binary segfaults at startup.
This happens in two cases:
Non-alloc sections (.symtab, .strtab, ...) sit after the last segment, so the new segment's file offset is larger than its virtual address. Make the virtual address equal the file offset.
Executables with a large .bss (e.g. Qt's lupdate) get the new PT_LOAD placed at a virtual address above its file offset. Pad the file so vaddr == file offset for executables.
grow-file.sh now passes.