From: Alex Lindsay <alexlindsay239@gmail.com>
Date: Thu, 17 Aug 2017 10:53:53 +0000 (+0100)
Subject: Synthetic symbol leak in elf_read_minimal_symbols
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=ba7139188c75a9c620cadea59158c5ffcab28acf;p=binutils-gdb.git

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 10d63b0ee1e..d2c194eff3b 100644
--- 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 ece704ca7c4..a6546613350 100644
--- 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