Synthetic symbol leak in elf_read_minimal_symbols

Detected this leak with valgrind memcheck:

==30840== 194 bytes in 1 blocks are definitely lost in loss record 9,138 of 10,922
==30840==    at 0x4C2DB8F: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==30840==    by 0x80DF82: bfd_malloc (libbfd.c:193)
==30840==    by 0x80E12D: bfd_zmalloc (libbfd.c:278)
==30840==    by 0x819E80: elf_x86_64_get_synthetic_symtab (elf64-x86-64.c:6835)
==30840==    by 0x4F7B01: elf_read_minimal_symbols(objfile*, int, elfinfo const*) (elfread.c:1124)
==30840==    by 0x4F7CE7: elf_symfile_read(objfile*, enum_flags<symfile_add_flag>) (elfread.c:1182)
==30840==    by 0x7557FC: read_symbols(objfile*, enum_flags<symfile_add_flag>) (symfile.c:861)
==30840==    by 0x755EE1: syms_from_objfile_1(objfile*, section_addr_info*, enum_flags<symfile_add_flag>) (symfile.c:1062)

We perform a dynamic allocation in
elf64-x86-64.c:elf_x86_64_get_synthetic_symtab

  s = *ret = (asymbol *) bfd_zmalloc (size);

that appear to never get freed.

gdb:

2017-08-17  Alex Lindsay  <alexlindsay239@gmail.com>

	* elfread.c (elf_read_minimal_symbols): xfree synthsyms.

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 10d63b0ee1ef927fa0a4b1cd18781c476c34728f..d2c194eff3b2689d72d339cb2cce1c637f78b268 100644 (file)
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,7 @@
+2017-08-17  Alex Lindsay  <alexlindsay239@gmail.com>  (tiny change)
+
+       * elfread.c (elf_read_minimal_symbols): xfree synthsyms.
+
 2017-08-17  Ruslan Kabatsayev  <b7.10110111@gmail.com>
 
        * NEWS: Mention new shortcuts for nexti and stepi in TUI

diff --git a/gdb/elfread.c b/gdb/elfread.c
index ece704ca7c4c0309b3b753dc4f5b61cd3073a810..a654661335007e230fe9bf9ef7cf087d8c11bbf3 100644 (file)
--- a/gdb/elfread.c
+++ b/gdb/elfread.c
@@ -1132,6 +1132,9 @@ elf_read_minimal_symbols (struct objfile *objfile, int symfile_flags,
        synth_symbol_table[i] = synthsyms + i;
       elf_symtab_read (reader, objfile, ST_SYNTHETIC, synthcount,
                       synth_symbol_table.get (), true);
+
+      xfree (synthsyms);
+      synthsyms = NULL;
     }
 
   /* Install any minimal symbols that have been collected as the current