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0262507918
These unmangled function pointers reside on the heap and could
be targeted by exploit writers, effectively bypassing libio vtable
validation. Instead, we ignore these pointers and always call
malloc or free.
In theory, this is a backwards-incompatible change, but using the
global heap instead of the user-supplied callback functions should
have little application impact. (The old libstdc++ implementation
exposed this functionality via a public, undocumented constructor
in its strstreambuf class.)
(cherry picked from commit 4e8a6346cd
)
148 lines
4.3 KiB
C
148 lines
4.3 KiB
C
/* Copyright (C) 1995-2018 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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#include "libioP.h"
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#include "strfile.h"
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#include <stdio.h>
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#include <stdlib.h>
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#include <wchar.h>
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struct _IO_FILE_wmemstream
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{
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_IO_strfile _sf;
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wchar_t **bufloc;
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_IO_size_t *sizeloc;
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};
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static int _IO_wmem_sync (_IO_FILE* fp) __THROW;
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static void _IO_wmem_finish (_IO_FILE* fp, int) __THROW;
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static const struct _IO_jump_t _IO_wmem_jumps libio_vtable =
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{
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JUMP_INIT_DUMMY,
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JUMP_INIT (finish, _IO_wmem_finish),
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JUMP_INIT (overflow, (_IO_overflow_t) _IO_wstr_overflow),
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JUMP_INIT (underflow, (_IO_underflow_t) _IO_wstr_underflow),
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JUMP_INIT (uflow, (_IO_underflow_t) _IO_wdefault_uflow),
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JUMP_INIT (pbackfail, (_IO_pbackfail_t) _IO_wstr_pbackfail),
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JUMP_INIT (xsputn, _IO_wdefault_xsputn),
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JUMP_INIT (xsgetn, _IO_wdefault_xsgetn),
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JUMP_INIT (seekoff, _IO_wstr_seekoff),
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JUMP_INIT (seekpos, _IO_default_seekpos),
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JUMP_INIT (setbuf, _IO_default_setbuf),
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JUMP_INIT (sync, _IO_wmem_sync),
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JUMP_INIT (doallocate, _IO_wdefault_doallocate),
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JUMP_INIT (read, _IO_default_read),
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JUMP_INIT (write, _IO_default_write),
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JUMP_INIT (seek, _IO_default_seek),
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JUMP_INIT (close, _IO_default_close),
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JUMP_INIT (stat, _IO_default_stat),
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JUMP_INIT (showmanyc, _IO_default_showmanyc),
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JUMP_INIT (imbue, _IO_default_imbue)
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};
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/* Open a stream that writes into a malloc'd buffer that is expanded as
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necessary. *BUFLOC and *SIZELOC are updated with the buffer's location
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and the number of characters written on fflush or fclose. */
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_IO_FILE *
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open_wmemstream (wchar_t **bufloc, _IO_size_t *sizeloc)
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{
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struct locked_FILE
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{
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struct _IO_FILE_wmemstream fp;
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#ifdef _IO_MTSAFE_IO
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_IO_lock_t lock;
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#endif
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struct _IO_wide_data wd;
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} *new_f;
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wchar_t *buf;
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new_f = (struct locked_FILE *) malloc (sizeof (struct locked_FILE));
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if (new_f == NULL)
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return NULL;
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#ifdef _IO_MTSAFE_IO
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new_f->fp._sf._sbf._f._lock = &new_f->lock;
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#endif
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buf = calloc (1, _IO_BUFSIZ);
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if (buf == NULL)
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{
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free (new_f);
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return NULL;
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}
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_IO_no_init (&new_f->fp._sf._sbf._f, 0, 0, &new_f->wd, &_IO_wmem_jumps);
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_IO_fwide (&new_f->fp._sf._sbf._f, 1);
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_IO_wstr_init_static (&new_f->fp._sf._sbf._f, buf,
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_IO_BUFSIZ / sizeof (wchar_t), buf);
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new_f->fp._sf._sbf._f._flags2 &= ~_IO_FLAGS2_USER_WBUF;
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new_f->fp._sf._s._allocate_buffer_unused = (_IO_alloc_type) malloc;
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new_f->fp._sf._s._free_buffer_unused = (_IO_free_type) free;
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new_f->fp.bufloc = bufloc;
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new_f->fp.sizeloc = sizeloc;
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/* Disable single thread optimization. BZ 21735. */
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new_f->fp._sf._sbf._f._flags2 |= _IO_FLAGS2_NEED_LOCK;
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return (_IO_FILE *) &new_f->fp._sf._sbf;
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}
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static int
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_IO_wmem_sync (_IO_FILE *fp)
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{
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struct _IO_FILE_wmemstream *mp = (struct _IO_FILE_wmemstream *) fp;
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if (fp->_wide_data->_IO_write_ptr == fp->_wide_data->_IO_write_end)
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{
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_IO_wstr_overflow (fp, '\0');
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--fp->_wide_data->_IO_write_ptr;
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}
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*mp->bufloc = fp->_wide_data->_IO_write_base;
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*mp->sizeloc = (fp->_wide_data->_IO_write_ptr
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- fp->_wide_data->_IO_write_base);
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return 0;
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}
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static void
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_IO_wmem_finish (_IO_FILE *fp, int dummy)
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{
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struct _IO_FILE_wmemstream *mp = (struct _IO_FILE_wmemstream *) fp;
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*mp->bufloc = (wchar_t *) realloc (fp->_wide_data->_IO_write_base,
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(fp->_wide_data->_IO_write_ptr
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- fp->_wide_data->_IO_write_base + 1)
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* sizeof (wchar_t));
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if (*mp->bufloc != NULL)
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{
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size_t len = (fp->_wide_data->_IO_write_ptr
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- fp->_wide_data->_IO_write_base);
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(*mp->bufloc)[len] = '\0';
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*mp->sizeloc = len;
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fp->_wide_data->_IO_buf_base = NULL;
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}
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_IO_wstr_finish (fp, 0);
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}
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