libelf: Allow updating phdrs for any e_type.

elf[32|64]_updatenull would sanity check the e_type before allowing to
update the phdrs. This prevents creating an ET_REL file with phdrs. It
also prevents creating any vendor specific ELF file having phdrs. We
only check this when updating/writing out the file. But we would just
read such files. Don't prevent people from creating unexpected ELF files.
elflint will warn for such files.

While writing a new testcase for this another bug was found that
prevented updating a just created phdr because elf_getphdrnum would
sanity check the phdr offset in the file (which doesn't exist yet).
Fix that by only doing such a sanity check if the phdrs haven't been
read in or created yet.

This second bug should have been found by the existing elfshphehdr
test, but that test contained a typo checking elf_getphdrnum.
It tested that the called failed when there were no phdrs, but then
elf_getphdrnum should simply succeed and return zero.

https://bugzilla.redhat.com/show_bug.cgi?id=1352232

Signed-off-by: Mark Wielaard <[email protected]>

1 files changed, 2 insertions, 13 deletions

diff --git a/libelf/elf32_updatenull.c b/libelf/elf32_updatenull.c
index 75070628..939aa13e 100644
--- a/libelf/elf32_updatenull.c
+++ b/libelf/elf32_updatenull.c
@@ -1,5 +1,5 @@
 /* Update data structures for changes.
-   Copyright (C) 2000-2010, 2015 Red Hat, Inc.
+   Copyright (C) 2000-2010, 2015, 2016 Red Hat, Inc.
    This file is part of elfutils.
    Written by Ulrich Drepper <[email protected]>, 2000.
 
@@ -140,21 +140,10 @@ __elfw2(LIBELFBITS,updatenull_wrlock) (Elf *elf, int *change_bop, size_t shnum)
   off_t size = elf_typesize (LIBELFBITS, ELF_T_EHDR, 1);
 
   /* Set the program header position.  */
-  if (elf->state.ELFW(elf,LIBELFBITS).phdr == NULL
-      && (ehdr->e_type == ET_EXEC || ehdr->e_type == ET_DYN
-	  || ehdr->e_type == ET_CORE))
+  if (elf->state.ELFW(elf,LIBELFBITS).phdr == NULL)
     (void) __elfw2(LIBELFBITS,getphdr_wrlock) (elf);
   if (elf->state.ELFW(elf,LIBELFBITS).phdr != NULL)
     {
-      /* Only executables, shared objects, and core files have a program
-	 header.  */
-      if (ehdr->e_type != ET_EXEC && ehdr->e_type != ET_DYN
-	  && unlikely (ehdr->e_type != ET_CORE))
-	{
-	  __libelf_seterrno (ELF_E_INVALID_PHDR);
-	  return -1;
-	}
-
       size_t phnum;
       if (unlikely (__elf_getphdrnum_rdlock (elf, &phnum) != 0))
 	return -1;