Prevent use-after-free of bfd filename in gdb_bfd_close_or_warn

On Windows gcore is not implemented, and if you try it, you get an
heap-use-after-free error:

(gdb) gcore C:/gdb/build64/gdb-git-python3/gdb/testsuite/outputs/gdb.base/gcore-buffer-overflow/gcore-buffer-overflow.test
warning: cannot close "=================================================================
==10108==ERROR: AddressSanitizer: heap-use-after-free on address 0x1259ea503110 at pc 0x7ff6806e3936 bp 0x0062e01ed990 sp 0x0062e01ed140
READ of size 111 at 0x1259ea503110 thread T0
    #0 0x7ff6806e3935 in strlen C:/gcc/src/gcc-14.2.0/libsanitizer/sanitizer_common/sanitizer_common_interceptors.inc:391
    #1 0x7ff6807169c4 in __pformat_puts C:/gcc/src/mingw-w64-v12.0.0/mingw-w64-crt/stdio/mingw_pformat.c:558
    #2 0x7ff6807186c1 in __mingw_pformat C:/gcc/src/mingw-w64-v12.0.0/mingw-w64-crt/stdio/mingw_pformat.c:2514
    #3 0x7ff680713614 in __mingw_vsnprintf C:/gcc/src/mingw-w64-v12.0.0/mingw-w64-crt/stdio/mingw_vsnprintf.c:41
    #4 0x7ff67f34419f in vsnprintf(char*, unsigned long long, char const*, char*) C:/msys64/mingw64/x86_64-w64-mingw32/include/stdio.h:484
    #5 0x7ff67f34419f in string_vprintf[abi:cxx11](char const*, char*) C:/gdb/src/gdb.git/gdbsupport/common-utils.cc:106
    #6 0x7ff67b37b739 in cli_ui_out::do_message(ui_file_style const&, char const*, char*) C:/gdb/src/gdb.git/gdb/cli-out.c:227
    #7 0x7ff67ce3d030 in ui_out::call_do_message(ui_file_style const&, char const*, ...) C:/gdb/src/gdb.git/gdb/ui-out.c:571
    #8 0x7ff67ce4255a in ui_out::vmessage(ui_file_style const&, char const*, char*) C:/gdb/src/gdb.git/gdb/ui-out.c:740
    bminor#9 0x7ff67ce2c873 in ui_file::vprintf(char const*, char*) C:/gdb/src/gdb.git/gdb/ui-file.c:73
    bminor#10 0x7ff67ce7f83d in gdb_vprintf(ui_file*, char const*, char*) C:/gdb/src/gdb.git/gdb/utils.c:1881
    bminor#11 0x7ff67ce7f83d in vwarning(char const*, char*) C:/gdb/src/gdb.git/gdb/utils.c:181
    bminor#12 0x7ff67f3530eb in warning(char const*, ...) C:/gdb/src/gdb.git/gdbsupport/errors.cc:33
    #13 0x7ff67baed27f in gdb_bfd_close_warning C:/gdb/src/gdb.git/gdb/gdb_bfd.c:437
    #14 0x7ff67baed27f in gdb_bfd_close_or_warn C:/gdb/src/gdb.git/gdb/gdb_bfd.c:646
    #15 0x7ff67baed27f in gdb_bfd_unref(bfd*) C:/gdb/src/gdb.git/gdb/gdb_bfd.c:739
    #16 0x7ff68094b6f2 in gdb_bfd_ref_policy::decref(bfd*) C:/gdb/src/gdb.git/gdb/gdb_bfd.h:82
    #17 0x7ff68094b6f2 in gdb::ref_ptr<bfd, gdb_bfd_ref_policy>::~ref_ptr() C:/gdb/src/gdb.git/gdbsupport/gdb_ref_ptr.h:91
    #18 0x7ff67badf4d2 in gcore_command C:/gdb/src/gdb.git/gdb/gcore.c:176

0x1259ea503110 is located 16 bytes inside of 4064-byte region [0x1259ea503100,0x1259ea5040e0)
freed by thread T0 here:
    #0 0x7ff6806b1687 in free C:/gcc/src/gcc-14.2.0/libsanitizer/asan/asan_malloc_win.cpp:90
    #1 0x7ff67f2ae807 in objalloc_free C:/gdb/src/gdb.git/libiberty/objalloc.c:187
    #2 0x7ff67d7f56e3 in _bfd_free_cached_info C:/gdb/src/gdb.git/bfd/opncls.c:247
    #3 0x7ff67d7f2782 in _bfd_delete_bfd C:/gdb/src/gdb.git/bfd/opncls.c:180
    #4 0x7ff67d7f5df9 in bfd_close_all_done C:/gdb/src/gdb.git/bfd/opncls.c:960
    #5 0x7ff67d7f62ec in bfd_close C:/gdb/src/gdb.git/bfd/opncls.c:925
    #6 0x7ff67baecd27 in gdb_bfd_close_or_warn C:/gdb/src/gdb.git/gdb/gdb_bfd.c:643
    #7 0x7ff67baecd27 in gdb_bfd_unref(bfd*) C:/gdb/src/gdb.git/gdb/gdb_bfd.c:739
    #8 0x7ff68094b6f2 in gdb_bfd_ref_policy::decref(bfd*) C:/gdb/src/gdb.git/gdb/gdb_bfd.h:82
    bminor#9 0x7ff68094b6f2 in gdb::ref_ptr<bfd, gdb_bfd_ref_policy>::~ref_ptr() C:/gdb/src/gdb.git/gdbsupport/gdb_ref_ptr.h:91
    bminor#10 0x7ff67badf4d2 in gcore_command C:/gdb/src/gdb.git/gdb/gcore.c:176

It happens because gdb_bfd_close_or_warn uses a bfd-internal name for
the failing-close warning, after the close is finished, and the name
already freed:

static int
gdb_bfd_close_or_warn (struct bfd *abfd)
{
  int ret;
  const char *name = bfd_get_filename (abfd);

  for (asection *sect : gdb_bfd_sections (abfd))
    free_one_bfd_section (sect);

  ret = bfd_close (abfd);

  if (!ret)
    gdb_bfd_close_warning (name,
			   bfd_errmsg (bfd_get_error ()));

  return ret;
}

Fixed by making a copy of the name for the warning.

Approved-By: Andrew Burgess <[email protected]>

gdb/gdb_bfd.c

@@ -649,15 +649,16 @@ static int
 gdb_bfd_close_or_warn (struct bfd *abfd)
 {
   int ret;
-  const char *name = bfd_get_filename (abfd);
+  gdb::unique_xmalloc_ptr<char> name
+    = make_unique_xstrdup (bfd_get_filename (abfd));
 
   for (asection *sect : gdb_bfd_sections (abfd))
     free_one_bfd_section (sect);
 
   ret = bfd_close (abfd);
 
   if (!ret)
-    gdb_bfd_close_warning (name,
+    gdb_bfd_close_warning (name.get (),
 			   bfd_errmsg (bfd_get_error ()));
 
   return ret;