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[binutils-gdb] Remove dwarf2_per_objfile_free and use after free of dwarf2_per_objfile
- From: Simon Marchi <simark at sourceware dot org>
- To: gdb-cvs at sourceware dot org
- Date: 28 Jan 2018 17:09:29 -0000
- Subject: [binutils-gdb] Remove dwarf2_per_objfile_free and use after free of dwarf2_per_objfile
https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=fc8e7e75c2be02237a7961688b06869814f36a18
commit fc8e7e75c2be02237a7961688b06869814f36a18
Author: Simon Marchi <simon.marchi@ericsson.com>
Date: Sun Jan 28 12:07:30 2018 -0500
Remove dwarf2_per_objfile_free and use after free of dwarf2_per_objfile
I got some crashes while doing some work with dwarf2_per_objfile. It
turns out that dwarf2_per_objfile_free is using the dwarf2_per_objfile
objects after their destructor has ran.
The easiest way to reproduce this is to run the inferior twice (do
"start" twice). Currently, it goes unnoticed, but when I tried to
change all_comp_units and all_type_units to std::vectors, things started
crashing.
The dwarf2_per_objfile objects get destroyed here:
#0 dwarf2_per_objfile::~dwarf2_per_objfile (this=0x35afe70, __in_chrg=<optimized out>) at /home/emaisin/src/binutils-gdb/gdb/dwarf2read.c:2422
#1 0x0000000000833282 in dwarf2_free_objfile (objfile=0x356cff0) at /home/emaisin/src/binutils-gdb/gdb/dwarf2read.c:25363
#2 0x0000000000699255 in elf_symfile_finish (objfile=0x356cff0) at /home/emaisin/src/binutils-gdb/gdb/elfread.c:1309
#3 0x0000000000911ed3 in objfile::~objfile (this=0x356cff0, __in_chrg=<optimized out>) at /home/emaisin/src/binutils-gdb/gdb/objfiles.c:674
and just after that the dwarf2read per-objfile registry cleanup function
gets called:
#0 dwarf2_per_objfile_free (objfile=0x356cff0, d=0x35afe70) at /home/emaisin/src/binutils-gdb/gdb/dwarf2read.c:25667
... registry boilerplate ...
#4 0x00000000009103ea in objfile_free_data (container=0x356cff0) at /home/emaisin/src/binutils-gdb/gdb/objfiles.c:61
#5 0x0000000000911ee2 in objfile::~objfile (this=0x356cff0, __in_chrg=<optimized out>) at /home/emaisin/src/binutils-gdb/gdb/objfiles.c:678
In dwarf2_per_objfile_free, we access fields of the dwarf2_per_objfile
object, which is invalid since its destructor has been executed.
This patch moves the content of dwarf2_per_objfile_free to the
destructor of dwarf2_per_objfile. The call to
register_objfile_data_with_cleanup in _initialize_dwarf2_read can be
changed to the simpler register_objfile_data.
gdb/ChangeLog:
* dwarf2read.c (free_dwo_files): Add forward-declaration.
(dwarf2_per_objfile::~dwarf2_per_objfile): Move content from
dwarf2_per_objfile_free here.
(dwarf2_per_objfile_free): Remove.
(_initialize_dwarf2_read): Don't register
dwarf2_per_objfile_free as a registry cleanup.
Diff:
---
gdb/ChangeLog | 9 +++++++++
gdb/dwarf2read.c | 57 ++++++++++++++++++++++++--------------------------------
2 files changed, 33 insertions(+), 33 deletions(-)
diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 5369e02..c422005 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,12 @@
+2018-01-28 Simon Marchi <simon.marchi@ericsson.com>
+
+ * dwarf2read.c (free_dwo_files): Add forward-declaration.
+ (dwarf2_per_objfile::~dwarf2_per_objfile): Move content from
+ dwarf2_per_objfile_free here.
+ (dwarf2_per_objfile_free): Remove.
+ (_initialize_dwarf2_read): Don't register
+ dwarf2_per_objfile_free as a registry cleanup.
+
2018-01-27 Eli Zaretskii <eliz@gnu.org>
Avoid compilation errors in MinGW native builds
diff --git a/gdb/dwarf2read.c b/gdb/dwarf2read.c
index 96026a8..51d0f39 100644
--- a/gdb/dwarf2read.c
+++ b/gdb/dwarf2read.c
@@ -2418,6 +2418,8 @@ dwarf2_per_objfile::dwarf2_per_objfile (struct objfile *objfile_,
locate_sections (obfd, sec, *names);
}
+static void free_dwo_files (htab_t dwo_files, struct objfile *objfile);
+
dwarf2_per_objfile::~dwarf2_per_objfile ()
{
/* Cached DIE trees use xmalloc and the comp_unit_obstack. */
@@ -2429,6 +2431,27 @@ dwarf2_per_objfile::~dwarf2_per_objfile ()
if (line_header_hash)
htab_delete (line_header_hash);
+ for (int ix = 0; ix < n_comp_units; ++ix)
+ VEC_free (dwarf2_per_cu_ptr, all_comp_units[ix]->imported_symtabs);
+
+ for (int ix = 0; ix < n_type_units; ++ix)
+ VEC_free (dwarf2_per_cu_ptr,
+ all_type_units[ix]->per_cu.imported_symtabs);
+ xfree (all_type_units);
+
+ VEC_free (dwarf2_section_info_def, types);
+
+ if (dwo_files != NULL)
+ free_dwo_files (dwo_files, objfile);
+ if (dwp_file != NULL)
+ gdb_bfd_unref (dwp_file->dbfd);
+
+ if (dwz_file != NULL && dwz_file->dwz_bfd)
+ gdb_bfd_unref (dwz_file->dwz_bfd);
+
+ if (index_table != NULL)
+ index_table->~mapped_index ();
+
/* Everything else should be on the objfile obstack. */
}
@@ -25470,37 +25493,6 @@ show_dwarf_cmd (const char *args, int from_tty)
cmd_show_list (show_dwarf_cmdlist, from_tty, "");
}
-/* Free data associated with OBJFILE, if necessary. */
-
-static void
-dwarf2_per_objfile_free (struct objfile *objfile, void *d)
-{
- struct dwarf2_per_objfile *data = (struct dwarf2_per_objfile *) d;
- int ix;
-
- for (ix = 0; ix < data->n_comp_units; ++ix)
- VEC_free (dwarf2_per_cu_ptr, data->all_comp_units[ix]->imported_symtabs);
-
- for (ix = 0; ix < data->n_type_units; ++ix)
- VEC_free (dwarf2_per_cu_ptr,
- data->all_type_units[ix]->per_cu.imported_symtabs);
- xfree (data->all_type_units);
-
- VEC_free (dwarf2_section_info_def, data->types);
-
- if (data->dwo_files)
- free_dwo_files (data->dwo_files, objfile);
- if (data->dwp_file)
- gdb_bfd_unref (data->dwp_file->dbfd);
-
- if (data->dwz_file && data->dwz_file->dwz_bfd)
- gdb_bfd_unref (data->dwz_file->dwz_bfd);
-
- if (data->index_table != NULL)
- data->index_table->~mapped_index ();
-}
-
-
/* The "save gdb-index" command. */
/* Write SIZE bytes from the buffer pointed to by DATA to FILE, with
@@ -27132,8 +27124,7 @@ _initialize_dwarf2_read (void)
{
struct cmd_list_element *c;
- dwarf2_objfile_data_key
- = register_objfile_data_with_cleanup (NULL, dwarf2_per_objfile_free);
+ dwarf2_objfile_data_key = register_objfile_data ();
add_prefix_cmd ("dwarf", class_maintenance, set_dwarf_cmd, _("\
Set DWARF specific variables.\n\