On a dynamic ELF executable, the current kernel loader gives to the interpreter (in the AUXV vector) the AT_PHDR argument as : offset_of_phdr_in_file + first address. It can be wrong for an executable where the program headers are not located in the first loaded segment. This patch corrects the behaviour. Signed-off-by: Quentin Godfroy <godfroy@xxxxxxxxxxxxxx> --- Here is an example of such an ELF executable which the current code fails on : ftp://quatramaran.ens.fr/pub/godfroy/addrpath/broken-sample --- linux-2.6.21.1/fs/binfmt_elf.c 2007-05-04 03:20:00.000000000 -0400 +++ linux-2.6.21.1-patch/fs/binfmt_elf.c 2007-05-04 08:02:18.000000000 -0400 @@ -134,6 +134,7 @@ static int padzero(unsigned long elf_bss static int create_elf_tables(struct linux_binprm *bprm, struct elfhdr *exec, int interp_aout, unsigned long load_addr, + unsigned long phdr_addr, unsigned long interp_load_addr) { unsigned long p = bprm->p; @@ -190,7 +191,7 @@ create_elf_tables(struct linux_binprm *b NEW_AUX_ENT(AT_HWCAP, ELF_HWCAP); NEW_AUX_ENT(AT_PAGESZ, ELF_EXEC_PAGESIZE); NEW_AUX_ENT(AT_CLKTCK, CLOCKS_PER_SEC); - NEW_AUX_ENT(AT_PHDR, load_addr + exec->e_phoff); + NEW_AUX_ENT(AT_PHDR, phdr_addr); NEW_AUX_ENT(AT_PHENT, sizeof(struct elf_phdr)); NEW_AUX_ENT(AT_PHNUM, exec->e_phnum); NEW_AUX_ENT(AT_BASE, interp_load_addr); @@ -529,7 +530,7 @@ static unsigned long randomize_stack_top static int load_elf_binary(struct linux_binprm *bprm, struct pt_regs *regs) { struct file *interpreter = NULL; /* to shut gcc up */ - unsigned long load_addr = 0, load_bias = 0; + unsigned long load_addr = 0, load_bias = 0, phdr_addr = 0; int load_addr_set = 0; char * elf_interpreter = NULL; unsigned int interpreter_type = INTERPRETER_NONE; @@ -718,6 +719,16 @@ static int load_elf_binary(struct linux_ break; } + elf_ppnt = elf_phdata; + for (i = 0; i< loc->elf_ex.e_phnum; i++, elf_ppnt++) + if (elf_ppnt->p_type == PT_PHDR) { + phdr_addr = elf_ppnt->p_vaddr; + break; + } + retval = -ENOEXEC; + if (!phdr_addr) + goto out_free_dentry; + /* Some simple consistency checks for the interpreter */ if (elf_interpreter) { interpreter_type = INTERPRETER_ELF | INTERPRETER_AOUT; @@ -987,7 +998,7 @@ static int load_elf_binary(struct linux_ current->flags &= ~PF_FORKNOEXEC; create_elf_tables(bprm, &loc->elf_ex, (interpreter_type == INTERPRETER_AOUT), - load_addr, interp_load_addr); + load_addr, phdr_addr, interp_load_addr); /* N.B. passed_fileno might not be initialized? */ if (interpreter_type == INTERPRETER_AOUT) current->mm->arg_start += strlen(passed_fileno) + 1; - To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
