readelf [PATCH]

[Sergei Pachkov <spigel at olvs dot miee dot ru>]

Hello.
I have found a little bug in "readelf" this weekend.
Sometimes variable called "process_headers" may have NULL value and its 
members reading would be failed.
For avoid this problem I have wrote little patch.
In the patch I have add few checks of variable process_headers like this:
if (process_headers != NULL)
or
if (process_headers == NULL)
--- readelf.c.orig	Mon Nov  4 12:15:56 2002
+++ readelf.c	Mon Nov  4 12:29:32 2002
@@ -354,15 +354,21 @@ get_data (var, file, offset, size, reaso
      const char *reason;
 {
   PTR mvar;
-
+  int err;
+  int c;
+  
   if (size == 0)
     return NULL;
 
-  if (fseek (file, offset, SEEK_SET))
+  err = fseek (file, offset, SEEK_SET);
+  Ó = getc(file);
+
+  if ((Ó == EOF) || (err != 0))
     {
       error (_("Unable to seek to %x for %s\n"), offset, reason);
       return NULL;
     }
+  ungetc(Ó,file); 	/* push C back to stream */
 
   mvar = var;
   if (mvar == NULL)
@@ -3444,6 +3450,10 @@ process_section_headers (file)
   dynamic_syminfo = NULL;
   symtab_shndx_hdr = NULL;
 
+ if (section_headers != NULL) 	/* sometimes section_headers may be NULL, 
+				   i.e. when section offset is wrong or
+				   allocation memory space for section_headers has been failed. */
+{
   for (i = 0, section = section_headers;
        i < elf_header.e_shnum;
        i ++, section ++)
@@ -3511,7 +3521,7 @@ process_section_headers (file)
       else if (do_debug_frames && strcmp (name, ".eh_frame") == 0)
 	request_dump (i, DEBUG_DUMP);
     }
-
+}
   if (! do_sections)
     return 1;
 
@@ -3532,6 +3542,9 @@ process_section_headers (file)
       printf (_("       Size              EntSize          Flags  Link  Info  Align\n"));
     }
 
+if (section_headers != NULL)
+{
+
   for (i = 0, section = section_headers;
        i < elf_header.e_shnum;
        i ++, section ++)
@@ -3623,7 +3636,7 @@ process_section_headers (file)
 		  (unsigned long) section->sh_addralign);
 	}
     }
-
+}
   printf (_("Key to Flags:\n\
   W (write), A (alloc), X (execute), M (merge), S (strings)\n\
   I (info), L (link order), G (group), x (unknown)\n\
@@ -3699,7 +3712,8 @@ process_relocs (file)
       Elf32_Internal_Shdr *     section;
       unsigned long		i;
       int		found = 0;
-
+if (section_headers != NULL)
+{
       for (i = 0, section = section_headers;
 	   i < elf_header.e_shnum;
 	   i++, section ++)
@@ -3762,7 +3776,7 @@ process_relocs (file)
 	      found = 1;
 	    }
 	}
-
+}
       if (! found)
 	printf (_("\nThere are no relocations in this file.\n"));
     }
@@ -3989,7 +4003,6 @@ slurp_ia64_unwind_table (file, aux, sec)
   free (table);
 
   /* Third, apply any relocations to the unwind table: */
-
   for (relsec = section_headers;
        relsec < section_headers + elf_header.e_shnum;
        ++relsec)
@@ -4058,7 +4071,6 @@ slurp_ia64_unwind_table (file, aux, sec)
 
       free (rela);
     }
-
   aux->table_len = size / (3 * addr_size);
   return 1;
 }
@@ -4083,7 +4095,8 @@ process_unwind (file)
   memset (& aux, 0, sizeof (aux));
 
   addr_size = is_32bit_elf ? 4 : 8;
-
+if (section_headers != NULL)
+{
   for (i = 0, sec = section_headers; i < elf_header.e_shnum; ++i, ++sec)
     {
       if (sec->sh_type == SHT_SYMTAB)
@@ -4190,7 +4203,7 @@ process_unwind (file)
 	  aux.info = NULL;
 	}
     }
-
+}
   if (aux.symtab)
     free (aux.symtab);
   if (aux.strtab)
@@ -5031,7 +5044,8 @@ process_version_sections (file)
 
   if (! do_version)
     return 1;
-
+if (section_headers != NULL)
+{
   for (i = 0, section = section_headers;
        i < elf_header.e_shnum;
        i++, section ++)
@@ -5420,6 +5434,7 @@ process_version_sections (file)
 	  break;
 	}
     }
+}
 
   if (! found)
     printf (_("\nNo version information found in this file.\n"));
@@ -5662,7 +5677,8 @@ process_symbol_table (file)
   else if (do_syms && !do_using_dynamic)
     {
       unsigned int     i;
-
+if (section_headers != NULL)
+{
       for (i = 0, section = section_headers;
 	   i < elf_header.e_shnum;
 	   i++, section++)
@@ -5853,6 +5869,7 @@ process_symbol_table (file)
 	  if (strtab != string_table)
 	    free (strtab);
 	}
+}
     }
   else if (do_syms)
     printf
@@ -9077,6 +9094,7 @@ process_section_contents (file)
 
   if (! do_dump)
     return 1;
+if (section_headers == NULL) return 1;
 
   /* Pre-scan the debug sections to find some debug information not
      present in some of them.  For the .debug_line, we must find out the
@@ -9558,6 +9576,7 @@ process_gnu_liblist (file)
 
   if (! do_arch)
     return 0;
+if (section_headers == NULL) return 0;
 
   for (i = 0, section = section_headers;
        i < elf_header.e_shnum;