PR24435, buffer overflow reading dynamic entries

[deliverable/binutils-gdb.git] / bfd / elflink.c

diff --git a/bfd/elflink.c b/bfd/elflink.c
index e50c0e4b38e932bc8240485269c4f59572e1a896..8aae9808a1d2889ac9e7921252dbe525bc5eb9a3 100644 (file)
--- a/bfd/elflink.c
+++ b/bfd/elflink.c
@@ -1941,6 +1941,7 @@ _bfd_elf_add_default_symbol (bfd *abfd,
        {
          bh = &hi->root;
          if (bh->type == bfd_link_hash_defined
+             && bh->u.def.section->owner != NULL
              && (bh->u.def.section->owner->flags & BFD_PLUGIN) != 0)
            {
              /* Mark the previous definition from IR object as
@@ -2522,9 +2523,11 @@ elf_link_read_relocs_from_section (bfd *abfd,
     }
 
   erela = (const bfd_byte *) external_relocs;
-  erelaend = erela + shdr->sh_size;
+  /* Setting erelaend like this and comparing with <= handles case of
+     a fuzzed object with sh_size not a multiple of sh_entsize.  */
+  erelaend = erela + shdr->sh_size - shdr->sh_entsize;
   irela = internal_relocs;
-  while (erela < erelaend)
+  while (erela <= erelaend)
     {
       bfd_vma r_symndx;
 
@@ -3872,6 +3875,7 @@ elf_link_add_object_symbols (bfd *abfd, struct bfd_link_info *info)
   struct elf_link_hash_entry **sym_hash;
   bfd_boolean dynamic;
   Elf_External_Versym *extversym = NULL;
+  Elf_External_Versym *extversym_end = NULL;
   Elf_External_Versym *ever;
   struct elf_link_hash_entry *weaks;
   struct elf_link_hash_entry **nondeflt_vers = NULL;
@@ -4072,7 +4076,7 @@ error_free_dyn:
          shlink = elf_elfsections (abfd)[elfsec]->sh_link;
 
          for (extdyn = dynbuf;
-              extdyn < dynbuf + s->size;
+              extdyn <= dynbuf + s->size - bed->s->sizeof_dyn;
               extdyn += bed->s->sizeof_dyn)
            {
              Elf_Internal_Dyn dyn;
@@ -4297,13 +4301,14 @@ error_free_dyn:
          Elf_Internal_Shdr *versymhdr;
 
          versymhdr = &elf_tdata (abfd)->dynversym_hdr;
-         extversym = (Elf_External_Versym *) bfd_malloc (versymhdr->sh_size);
+         amt = versymhdr->sh_size;
+         extversym = (Elf_External_Versym *) bfd_malloc (amt);
          if (extversym == NULL)
            goto error_free_sym;
-         amt = versymhdr->sh_size;
          if (bfd_seek (abfd, versymhdr->sh_offset, SEEK_SET) != 0
              || bfd_bread (extversym, amt, abfd) != amt)
            goto error_free_vers;
+         extversym_end = extversym + (amt / sizeof (* extversym));
        }
     }
 
@@ -4378,7 +4383,20 @@ error_free_dyn:
     }
 
   weaks = NULL;
-  ever = extversym != NULL ? extversym + extsymoff : NULL;
+  if (extversym == NULL)
+    ever = NULL;
+  else if (extversym + extsymoff < extversym_end)
+    ever = extversym + extsymoff;
+  else
+    {
+      /* xgettext:c-format */
+      _bfd_error_handler (_("%pB: invalid version offset %lx (max %lx)"),
+                         abfd, (long) extsymoff,
+                         (long) (extversym_end - extversym) / sizeof (* extversym));
+      bfd_set_error (bfd_error_bad_value);
+      goto error_free_vers;
+    }
+
   for (isym = isymbuf, isymend = isymbuf + extsymcount;
        isym < isymend;
        isym++, sym_hash++, ever = (ever != NULL ? ever + 1 : NULL))
@@ -4424,7 +4442,13 @@ error_free_dyn:
             global symbols follow all local symbols, and that sh_info
             point to the first global symbol.  Unfortunately, Irix 5
             screws this up.  */
-         continue;
+         if (elf_bad_symtab (abfd))
+           continue;
+
+         /* If we aren't prepared to handle locals within the globals
+            then we'll likely segfault on a NULL section.  */
+         bfd_set_error (bfd_error_bad_value);
+         goto error_free_vers;
 
        case STB_GLOBAL:
          if (isym->st_shndx != SHN_UNDEF && !common)
@@ -4562,6 +4586,14 @@ error_free_dyn:
              else
                iver.vs_vers = 0;
            }
+         else if (ever >= extversym_end)
+           {
+             /* xgettext:c-format */
+             _bfd_error_handler (_("%pB: not enough version information"),
+                                 abfd);
+             bfd_set_error (bfd_error_bad_value);
+             goto error_free_vers;
+           }
          else
            _bfd_elf_swap_versym_in (abfd, ever, &iver);
 
@@ -10389,8 +10421,7 @@ elf_link_input_bfd (struct elf_final_link_info *flinfo, bfd *input_bfd)
            {
              /* Don't attempt to output symbols with st_shnx in the
                 reserved range other than SHN_ABS and SHN_COMMON.  */
-             *ppsection = NULL;
-             continue;
+             isec = bfd_und_section_ptr;
            }
          else if (isec->sec_info_type == SEC_INFO_TYPE_MERGE
                   && ELF_ST_TYPE (isym->st_info) != STT_SECTION)