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Synthetic symbol leak in in elf_x86_64_get_synthetic_symtab and elf_read_minimal_symbols


Detected this leak with valgrind memcheck:

==21225== 463 (336 direct, 127 indirect) bytes in 1 blocks are definitely lost in loss record 10,770 of 10,949^M ==21225== at 0x4C2DB8F: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)^M
==21225==    by 0x6C6DA2: bfd_malloc (libbfd.c:193)^M
==21225==    by 0x6C6F4D: bfd_zmalloc (libbfd.c:278)^M
==21225== by 0x6D252E: elf_x86_64_get_synthetic_symtab (elf64-x86-64.c:6846)^M
==21225==    by 0x4B397A: elf_read_minimal_symbols (elfread.c:1124)^M
==21225== by 0x4B397A: elf_symfile_read(objfile*, enum_flags<symfile_add_flag>) (elfread.c:1182)^M ==21225== by 0x63AC94: read_symbols(objfile*, enum_flags<symfile_add_flag>) (symfile.c:861)^M
==21225==    by 0x63A773: syms_from_objfile_1 (symfile.c:1062)

We perform a couple of dynamic allocations in elf_x86_64_get_synthetic_symtab (elf64-x86-64.c):

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

  names = (char *) bfd_malloc (size);

that appear to never get freed. My patch for this:

diff --git a/gdb/elfread.c b/gdb/elfread.c
index ece704ca7c..5ed8a6f957 100644
--- a/gdb/elfread.c
+++ b/gdb/elfread.c
@@ -1144,6 +1144,9 @@ elf_read_minimal_symbols (struct objfile *objfile, int symfile_flags,

   if (symtab_create_debug)
     fprintf_unfiltered (gdb_stdlog, "Done reading minimal symbols.\n");
+  if (synthcount > 0)
+    xfree ((char *) synthsyms->name);
+  xfree (synthsyms);
 }

 /* Scan and build partial symbols for a symbol file.


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