PR 14444, degenerate SHT_GROUP

PR 14444, degenerate SHT_GROUP

[Alan Modra]

Allowing SHT_GROUP sections that only contain a flag word doesn't seem
to break anything in BFD, so don't reject files that have empty
groups.  I don't see anything in the ELF spec that forbids such.

	PR binutils/14444
	* elf.c (IS_VALID_GROUP_SECTION_HEADER) Add minsize param.
	(setup_group): Adjust uses.
	(bfd_section_from_shdr): Allow SHT_GROUP sections with just a flag
	word.

Index: bfd/elf.c
===================================================================
RCS file: /cvs/src/src/bfd/elf.c,v
retrieving revision 1.568
diff -u -p -r1.568 elf.c
--- bfd/elf.c	24 Jul 2012 21:06:57 -0000	1.568
+++ bfd/elf.c	10 Aug 2012 02:02:31 -0000
@@ -545,9 +545,9 @@ setup_group (bfd *abfd, Elf_Internal_Shd
       shnum = elf_numsections (abfd);
       num_group = 0;
 
-#define IS_VALID_GROUP_SECTION_HEADER(shdr)		\
+#define IS_VALID_GROUP_SECTION_HEADER(shdr, minsize)	\
 	(   (shdr)->sh_type == SHT_GROUP		\
-	 && (shdr)->sh_size >= (2 * GRP_ENTRY_SIZE)	\
+	 && (shdr)->sh_size >= minsize			\
 	 && (shdr)->sh_entsize == GRP_ENTRY_SIZE	\
 	 && ((shdr)->sh_size % GRP_ENTRY_SIZE) == 0)
 
@@ -555,7 +555,7 @@ setup_group (bfd *abfd, Elf_Internal_Shd
 	{
 	  Elf_Internal_Shdr *shdr = elf_elfsections (abfd)[i];
 
-	  if (IS_VALID_GROUP_SECTION_HEADER (shdr))
+	  if (IS_VALID_GROUP_SECTION_HEADER (shdr, 2 * GRP_ENTRY_SIZE))
 	    num_group += 1;
 	}
 
@@ -581,7 +581,7 @@ setup_group (bfd *abfd, Elf_Internal_Shd
 	    {
 	      Elf_Internal_Shdr *shdr = elf_elfsections (abfd)[i];
 
-	      if (IS_VALID_GROUP_SECTION_HEADER (shdr))
+	      if (IS_VALID_GROUP_SECTION_HEADER (shdr, 2 * GRP_ENTRY_SIZE))
 		{
 		  unsigned char *src;
 		  Elf_Internal_Group *dest;
@@ -1929,7 +1929,7 @@ bfd_section_from_shdr (bfd *abfd, unsign
       return TRUE;
 
     case SHT_GROUP:
-      if (! IS_VALID_GROUP_SECTION_HEADER (hdr))
+      if (! IS_VALID_GROUP_SECTION_HEADER (hdr, GRP_ENTRY_SIZE))
 	return FALSE;
       if (!_bfd_elf_make_section_from_shdr (abfd, hdr, name, shindex))
 	return FALSE;

-- 
Alan Modra
Australia Development Lab, IBM