[ARM] LD / BFD segfault with local, absolute symbol

[Thomas Schwinge]

Hello!

When processing an object file that contains a local, absolute symbol
with LD / BFD, there's a segfault:

    Program received signal SIGSEGV, Segmentation fault.
    0x0000000000451e9f in elf32_arm_size_stubs (output_bfd=0x7329c0, stub_bfd=0x747320, info=0x71ed60, group_size=1, 
        add_stub_section=0x422c65 <elf32_arm_add_stub_section>, layout_sections_again=0x422d42 <gldarm_layout_sections_again>) at ../../HEAD/src/bfd/elf32-arm.c:4505
    4505                          hdr = elf_elfsections (input_bfd)[sym->st_shndx];
    (gdb) list
    4500                              if (local_syms == NULL)
    4501                                goto error_ret_free_internal;
    4502                            }
    4503
    4504                          sym = local_syms + r_indx;
    4505                          hdr = elf_elfsections (input_bfd)[sym->st_shndx];
    4506                          sym_sec = hdr->bfd_section;
    4507                          if (!sym_sec)
    4508                            /* This is an undefined symbol.  It can never
    4509                               be resolved. */
    (gdb) bt
    #0  0x0000000000451e9f in elf32_arm_size_stubs (output_bfd=0x7329c0, stub_bfd=0x747320, info=0x71ed60, group_size=1, 
        add_stub_section=0x422c65 <elf32_arm_add_stub_section>, layout_sections_again=0x422d42 <gldarm_layout_sections_again>) at ../../HEAD/src/bfd/elf32-arm.c:4505
    #1  0x00000000004230ec in gldarmelf_after_allocation () at earmelf.c:426
    #2  0x000000000041e87f in ldemul_after_allocation () at ../../HEAD/src/ld/ldemul.c:72
    #3  0x0000000000415bcc in lang_process () at ../../HEAD/src/ld/ldlang.c:6427
    #4  0x0000000000419837 in main (argc=4, argv=0x7fffffffdc28) at ../../HEAD/src/ld/ldmain.c:457
    (gdb) print *sym
    $1 = {st_value = 2147483672, st_size = 0, st_name = 4, st_info = 0 '\000', st_other = 0 '\000', st_shndx = 4294967281}
    (gdb) print /x sym->st_value
    $2 = 0x80000018
    (gdb) print /x sym->st_shndx
    $3 = 0xfffffff1

The latter one is surely an invalid array index -- it is SHN_ABS.  Fixed
with this patch; this boilerplate code is used in a bunch of other files,
too.  OK to apply?

bfd/
2010-09-30  Thomas Schwinge  <thomas@codesourcery.com>

	* elf32-arm.c (elf32_arm_size_stubs): Don't choke on local symbols in
	SHN_UNDEF, SHN_ABS, SHN_COMMON.

Index: bfd/elf32-arm.c
===================================================================
RCS file: /cvs/src/src/bfd/elf32-arm.c,v
retrieving revision 1.242
diff -u -p -U4 -r1.242 elf32-arm.c
--- bfd/elf32-arm.c	24 Sep 2010 12:14:23 -0000	1.242
+++ bfd/elf32-arm.c	30 Sep 2010 09:06:16 -0000
@@ -4485,9 +4485,8 @@ elf32_arm_size_stubs (bfd *output_bfd,
 		  if (r_indx < symtab_hdr->sh_info)
 		    {
 		      /* It's a local symbol.  */
 		      Elf_Internal_Sym *sym;
-		      Elf_Internal_Shdr *hdr;
 
 		      if (local_syms == NULL)
 			{
 			  local_syms
@@ -4501,10 +4500,18 @@ elf32_arm_size_stubs (bfd *output_bfd,
 			    goto error_ret_free_internal;
 			}
 
 		      sym = local_syms + r_indx;
-		      hdr = elf_elfsections (input_bfd)[sym->st_shndx];
-		      sym_sec = hdr->bfd_section;
+		      if (sym->st_shndx == SHN_UNDEF)
+			sym_sec = bfd_und_section_ptr;
+		      else if (sym->st_shndx == SHN_ABS)
+			sym_sec = bfd_abs_section_ptr;
+		      else if (sym->st_shndx == SHN_COMMON)
+			sym_sec = bfd_com_section_ptr;
+		      else
+			sym_sec =
+			  bfd_section_from_elf_index (input_bfd, sym->st_shndx);
+
 		      if (!sym_sec)
 			/* This is an undefined symbol.  It can never
 			   be resolved. */
 			continue;


Regards,
 Thomas
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