Re: [mmotm:master 253/317] arch/mips/kernel/../../../fs/binfmt_elf.c:1140:7: error: 'elf_interpreter' undeclared; did you mean 'interpreter'?

[Kees Cook <keescook@chromium.org>]

On Wed, Apr 17, 2019 at 7:34 AM kbuild test robot <lkp@intel.com> wrote:
>
> tree:   git://git.cmpxchg.org/linux-mmotm.git master
> head:   def6be39d5629b938faba788330db817d19a04da
> commit: 8e5e08d49bf73afad16199d68c5e61a64f5df69d [253/317] fs/binfmt_elf.c: move brk out of mmap when doing direct loader exec
> config: mips-fuloong2e_defconfig (attached as .config)
> compiler: mips64el-linux-gnuabi64-gcc (Debian 7.2.0-11) 7.2.0
> reproduce:
>         wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
>         chmod +x ~/bin/make.cross
>         git checkout 8e5e08d49bf73afad16199d68c5e61a64f5df69d
>         # save the attached .config to linux build tree
>         GCC_VERSION=7.2.0 make.cross ARCH=mips
>
> All errors (new ones prefixed by >>):
>
>    In file included from arch/mips/kernel/binfmt_elfn32.c:106:0:
>    arch/mips/kernel/../../../fs/binfmt_elf.c: In function 'load_elf_binary':
> >> arch/mips/kernel/../../../fs/binfmt_elf.c:1140:7: error: 'elf_interpreter' undeclared (first use in this function); did you mean 'interpreter'?
>      if (!elf_interpreter)
>           ^~~~~~~~~~~~~~~
>           interpreter
>    arch/mips/kernel/../../../fs/binfmt_elf.c:1140:7: note: each undeclared identifier is reported only once for each function it appears in

Whoa. That was unexpected (.c getting #included!)

Especially since that's a local variable... I'll try to figure out
what's happening...

-Kees

>
> vim +1140 arch/mips/kernel/../../../fs/binfmt_elf.c
>
>   1122
>   1123          retval = create_elf_tables(bprm, &loc->elf_ex,
>   1124                            load_addr, interp_load_addr);
>   1125          if (retval < 0)
>   1126                  goto out;
>   1127          /* N.B. passed_fileno might not be initialized? */
>   1128          current->mm->end_code = end_code;
>   1129          current->mm->start_code = start_code;
>   1130          current->mm->start_data = start_data;
>   1131          current->mm->end_data = end_data;
>   1132          current->mm->start_stack = bprm->p;
>   1133
>   1134          /*
>   1135           * When executing a loader directly (ET_DYN without Interp), move
>   1136           * the brk area out of the mmap region (since it grows up, and may
>   1137           * collide early with the stack growing down), and into the unused
>   1138           * ELF_ET_DYN_BASE region.
>   1139           */
> > 1140          if (!elf_interpreter)
>   1141                  current->mm->brk = current->mm->start_brk = ELF_ET_DYN_BASE;
>   1142
>   1143          if ((current->flags & PF_RANDOMIZE) && (randomize_va_space > 1)) {
>   1144                  current->mm->brk = current->mm->start_brk =
>   1145                          arch_randomize_brk(current->mm);
>   1146  #ifdef compat_brk_randomized
>   1147                  current->brk_randomized = 1;
>   1148  #endif
>   1149          }
>   1150
>   1151          if (current->personality & MMAP_PAGE_ZERO) {
>   1152                  /* Why this, you ask???  Well SVr4 maps page 0 as read-only,
>   1153                     and some applications "depend" upon this behavior.
>   1154                     Since we do not have the power to recompile these, we
>   1155                     emulate the SVr4 behavior. Sigh. */
>   1156                  error = vm_mmap(NULL, 0, PAGE_SIZE, PROT_READ | PROT_EXEC,
>   1157                                  MAP_FIXED | MAP_PRIVATE, 0);
>   1158          }
>   1159
>
> ---
> 0-DAY kernel test infrastructure                Open Source Technology Center
> https://lists.01.org/pipermail/kbuild-all                   Intel Corporation



-- 
Kees Cook