Re: ASAN crash regression [Re: [PATCH 2/2] move the demangled_names_hash into the per-BFD] https://sourceware.org/ml/gdb-patches/2014-06/msg00550.html Jan> ./configure ... -fsanitize=address Jan> echo 'void f(){}main(){}'|gcc -x c++ - -g;ASAN_OPTIONS=symbolize=1 ASAN_SYMBOLIZER_PATH=/usr/bin/llvm-symbolizer ./gdb -batch a.out -ex 'file a.out' Readily seen with valgrind as well. Here's my proposed fix. Tom commit 3a93a67ad0ea3495f67c9708673345b73de2d806 Author: Tom Tromey Date: Mon Jun 16 03:17:19 2014 -0600 fix memory errors with demangled name hash This fixes a regression that Jan pointed out. The bug is that some names were allocated by dwarf2read on the objfile obstack, but then passed to SYMBOL_SET_NAMES with copy_name=0. This violates the invariant that the names must have a lifetime tied to the lifetime of the BFD. The fix is to allocate names on the per-BFD obstack. I looked at all callers, direct or indirect, of SYMBOL_SET_NAMES that pass copy_name=0. Note that only the ELF and DWARF readers do this; other symbol readers were never updated (and perhaps cannot be, depending on the details of the formats). This is why the patch is relatively small. Built and regtested on x86-64 Fedora 20. 2014-06-16 Tom Tromey * dwarf2read.c (fixup_go_packaging, dwarf2_compute_name) (dwarf2_physname, read_partial_die) (guess_partial_die_structure_name, fixup_partial_die) (guess_full_die_structure_name, anonymous_struct_prefix) (dwarf2_name): Use per-BFD obstack. ### a/gdb/ChangeLog ### b/gdb/ChangeLog ## -1,5 +1,13 @@ 2014-06-16 Tom Tromey + * dwarf2read.c (fixup_go_packaging, dwarf2_compute_name) + (dwarf2_physname, read_partial_die) + (guess_partial_die_structure_name, fixup_partial_die) + (guess_full_die_structure_name, anonymous_struct_prefix) + (dwarf2_name): Use per-BFD obstack. + +2014-06-16 Tom Tromey + * minsyms.h (prim_record_minimal_symbol) (prim_record_minimal_symbol_and_info): Update comments. --- a/gdb/dwarf2read.c +++ b/gdb/dwarf2read.c @@ -7745,9 +7745,10 @@ fixup_go_packaging (struct dwarf2_cu *cu) if (package_name != NULL) { struct objfile *objfile = cu->objfile; - const char *saved_package_name = obstack_copy0 (&objfile->objfile_obstack, - package_name, - strlen (package_name)); + const char *saved_package_name + = obstack_copy0 (&objfile->per_bfd->storage_obstack, + package_name, + strlen (package_name)); struct type *type = init_type (TYPE_CODE_MODULE, 0, 0, saved_package_name, objfile); struct symbol *sym; @@ -8365,6 +8366,8 @@ dwarf2_compute_name (const char *name, long length; const char *prefix; struct ui_file *buf; + char *intermediate_name; + const char *canonical_name = NULL; prefix = determine_prefix (die, cu); buf = mem_fileopen (); @@ -8541,19 +8544,25 @@ dwarf2_compute_name (const char *name, } } - name = ui_file_obsavestring (buf, &objfile->objfile_obstack, - &length); + intermediate_name = ui_file_xstrdup (buf, &length); ui_file_delete (buf); if (cu->language == language_cplus) - { - const char *cname - = dwarf2_canonicalize_name (name, cu, - &objfile->objfile_obstack); + canonical_name + = dwarf2_canonicalize_name (intermediate_name, cu, + &objfile->per_bfd->storage_obstack); + + /* If we only computed INTERMEDIATE_NAME, or if + INTERMEDIATE_NAME is already canonical, then we need to + copy it to the appropriate obstack. */ + if (canonical_name == NULL || canonical_name == intermediate_name) + name = obstack_copy0 (&objfile->per_bfd->storage_obstack, + intermediate_name, + strlen (intermediate_name)); + else + name = canonical_name; - if (cname != NULL) - name = cname; - } + xfree (intermediate_name); } } @@ -8562,7 +8571,7 @@ dwarf2_compute_name (const char *name, /* Return the fully qualified name of DIE, based on its DW_AT_name. If scope qualifiers are appropriate they will be added. The result - will be allocated on the objfile_obstack, or NULL if the DIE does + will be allocated on the storage_obstack, or NULL if the DIE does not have a name. NAME may either be from a previous call to dwarf2_name or NULL. @@ -8677,7 +8686,8 @@ dwarf2_physname (const char *name, struct die_info *die, struct dwarf2_cu *cu) retval = canon; if (need_copy) - retval = obstack_copy0 (&objfile->objfile_obstack, retval, strlen (retval)); + retval = obstack_copy0 (&objfile->per_bfd->storage_obstack, + retval, strlen (retval)); do_cleanups (back_to); return retval; @@ -15508,7 +15518,7 @@ read_partial_die (const struct die_reader_specs *reader, default: part_die->name = dwarf2_canonicalize_name (DW_STRING (&attr), cu, - &objfile->objfile_obstack); + &objfile->per_bfd->storage_obstack); break; } break; @@ -15793,7 +15803,7 @@ guess_partial_die_structure_name (struct partial_die_info *struct_pdi, if (actual_class_name != NULL) { struct_pdi->name - = obstack_copy0 (&cu->objfile->objfile_obstack, + = obstack_copy0 (&cu->objfile->per_bfd->storage_obstack, actual_class_name, strlen (actual_class_name)); xfree (actual_class_name); @@ -15879,8 +15889,9 @@ fixup_partial_die (struct partial_die_info *part_die, else base = demangled; - part_die->name = obstack_copy0 (&cu->objfile->objfile_obstack, - base, strlen (base)); + part_die->name + = obstack_copy0 (&cu->objfile->per_bfd->storage_obstack, + base, strlen (base)); xfree (demangled); } } @@ -18557,7 +18568,7 @@ guess_full_die_structure_name (struct die_info *die, struct dwarf2_cu *cu) && actual_name[actual_name_len - die_name_len - 1] == ':') name = - obstack_copy0 (&cu->objfile->objfile_obstack, + obstack_copy0 (&cu->objfile->per_bfd->storage_obstack, actual_name, actual_name_len - die_name_len - 2); } @@ -18603,7 +18614,7 @@ anonymous_struct_prefix (struct die_info *die, struct dwarf2_cu *cu) if (base == NULL || base == DW_STRING (attr) || base[-1] != ':') return ""; - return obstack_copy0 (&cu->objfile->objfile_obstack, + return obstack_copy0 (&cu->objfile->per_bfd->storage_obstack, DW_STRING (attr), &base[-1] - DW_STRING (attr)); } @@ -18943,8 +18954,9 @@ dwarf2_name (struct die_info *die, struct dwarf2_cu *cu) char *base; /* FIXME: we already did this for the partial symbol... */ - DW_STRING (attr) = obstack_copy0 (&cu->objfile->objfile_obstack, - demangled, strlen (demangled)); + DW_STRING (attr) + = obstack_copy0 (&cu->objfile->per_bfd->storage_obstack, + demangled, strlen (demangled)); DW_STRING_IS_CANONICAL (attr) = 1; xfree (demangled); @@ -18967,7 +18979,7 @@ dwarf2_name (struct die_info *die, struct dwarf2_cu *cu) { DW_STRING (attr) = dwarf2_canonicalize_name (DW_STRING (attr), cu, - &cu->objfile->objfile_obstack); + &cu->objfile->per_bfd->storage_obstack); DW_STRING_IS_CANONICAL (attr) = 1; } return DW_STRING (attr);