From 5febb0da6f6d7106c403e6809917d89d6ee081ad Mon Sep 17 00:00:00 2001 From: Dmitriy Ivanov Date: Mon, 28 Jul 2014 15:05:51 -0700 Subject: [PATCH] Fix 'adb shell /system/bin/linker' crash Bug: https://code.google.com/p/android/issues/detail?id=63174 (cherry picked from commit efe13832dccf2cec2898b89ca4418a6aac29d3eb) Change-Id: I43629e4a14870f67abc2dd5ff2e3040c47b2168d --- linker/linker.cpp | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-) diff --git a/linker/linker.cpp b/linker/linker.cpp index 4c765944a..59b99383e 100644 --- a/linker/linker.cpp +++ b/linker/linker.cpp @@ -2221,6 +2221,8 @@ static ElfW(Addr) get_elf_exec_load_bias(const ElfW(Ehdr)* elf) { return 0; } +extern "C" void _start(); + /* * This is the entry point for the linker, called from begin.S. This * method is responsible for fixing the linker's own relocations, and @@ -2238,12 +2240,23 @@ extern "C" ElfW(Addr) __linker_init(void* raw_args) { KernelArgumentBlock args(raw_args); ElfW(Addr) linker_addr = args.getauxval(AT_BASE); + ElfW(Addr) entry_point = args.getauxval(AT_ENTRY); ElfW(Ehdr)* elf_hdr = reinterpret_cast(linker_addr); ElfW(Phdr)* phdr = reinterpret_cast(linker_addr + elf_hdr->e_phoff); soinfo linker_so; memset(&linker_so, 0, sizeof(soinfo)); + // If the linker is not acting as PT_INTERP entry_point is equal to + // _start. Which means that the linker is running as an executable and + // already linked by PT_INTERP. + // + // This happens when user tries to run 'adb shell /system/bin/linker' + // see also https://code.google.com/p/android/issues/detail?id=63174 + if (reinterpret_cast(&_start) == entry_point) { + __libc_fatal("This is %s, the helper program for shared library executables.\n", args.argv[0]); + } + strcpy(linker_so.name, "[dynamic linker]"); linker_so.base = linker_addr; linker_so.size = phdr_table_get_load_size(phdr, elf_hdr->e_phnum); @@ -2265,7 +2278,7 @@ extern "C" ElfW(Addr) __linker_init(void* raw_args) { _exit(EXIT_FAILURE); } - // lets properly initialize global variables + // Initialize the linker's own global variables linker_so.CallConstructors(); // We have successfully fixed our own relocations. It's safe to run