[patch] Fix off-by-one bug in elfread.c

[patch] Fix off-by-one bug in elfread.c

[Paul Pluzhnikov]

Greetings,

While running GDB under Valgrind, I noticed a bunch of errors like this:

==32593== Conditional jump or move depends on uninitialised value(s)
==32593==    at 0x574F4E: symbol_set_names (/home/src/gdb/symtab.c:622)
==32593==    by 0x460D20: prim_record_minimal_symbol_full (/home/src/gdb/minsyms.c:904)
==32593==    by 0x51E9B8: record_minimal_symbol (/home/src/gdb/elfread.c:204)
==32593==    by 0x51F788: elf_rel_plt_read (/home/src/gdb/elfread.c:679)
==32593==    by 0x520F2C: elf_symfile_read (/home/src/gdb/elfread.c:1302)
==32593==    by 0x58293D: syms_from_objfile (/home/src/gdb/symfile.c:1016)
==32593==    by 0x582B6E: symbol_file_add_with_addrs_or_offsets (/home/src/gdb/symfile.c:1125)
==32593==    by 0x582D88: symbol_file_add_from_bfd (/home/src/gdb/symfile.c:1217)
==32593==    by 0x4759E4: solib_read_symbols (/home/src/gdb/solib.c:651)
==32593==    by 0x476008: solib_add (/home/src/gdb/solib.c:960)
==32593==    by 0x49E608: enable_break (/home/src/gdb/solib-svr4.c:1556)
==32593==    by 0x49F5EE: svr4_solib_create_inferior_hook (/home/src/gdb/solib-svr4.c:2210)

AFAICT, they are the result of off-by-one bug in elf_rel_plt_read.
Patch attached.

Thanks,

--
Paul Pluzhnikov

2011-07-22  Paul Pluzhnikov  <ppluzhnikov@google.com>

	* elfread.c (elf_rel_plt_read): Fix off-by-one bug.



Index: elfread.c
===================================================================
RCS file: /cvs/src/src/gdb/elfread.c,v
retrieving revision 1.116
diff -u -p -r1.116 elfread.c
--- elfread.c	26 May 2011 07:47:10 -0000	1.116
+++ elfread.c	22 Jul 2011 22:49:06 -0000
@@ -667,14 +667,14 @@ elf_rel_plt_read (struct objfile *objfil
 	 OBJFILE the symbol is undefined and the objfile having NAME defined
 	 may not yet have been loaded.  */
 
-      if (string_buffer_size < name_len + got_suffix_len)
+      if (string_buffer_size < name_len + got_suffix_len + 1)
 	{
 	  string_buffer_size = 2 * (name_len + got_suffix_len);
 	  string_buffer = xrealloc (string_buffer, string_buffer_size);
 	}
       memcpy (string_buffer, name, name_len);
       memcpy (&string_buffer[name_len], SYMBOL_GOT_PLT_SUFFIX,
-	      got_suffix_len);
+	      got_suffix_len + 1);
 
       msym = record_minimal_symbol (string_buffer, name_len + got_suffix_len,
                                     1, address, mst_slot_got_plt, got_plt,

Re: [patch] Fix off-by-one bug in elfread.c

[Jan Kratochvil]

On Sat, 23 Jul 2011 01:03:58 +0200, Paul Pluzhnikov wrote:
> AFAICT, they are the result of off-by-one bug in elf_rel_plt_read.
> Patch attached.

I agree, check it in, please.


Sorry,
Jan