IABSD.fr/src/lib/libssl/tls13_buffer.c

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• Author : jsing
  Date : 2020-03-10 17:11:25
  Hash : 96130b2d
  Message : Add a return value check to tls13_buffer_extend(). In the unlikely event that the return value from the read callback is larger than the number of bytes we asked for, we can end up incrementing buf->len beyond capacity. Check the return value from the read callback to prevent this. ok inoguchi@ tb@

• lib/libssl/tls13_buffer.c

• /* $OpenBSD: tls13_buffer.c,v 1.3 2020/03/10 17:11:25 jsing Exp $ */
  /*
   * Copyright (c) 2018, 2019 Joel Sing <jsing@openbsd.org>
   *
   * Permission to use, copy, modify, and distribute this software for any
   * purpose with or without fee is hereby granted, provided that the above
   * copyright notice and this permission notice appear in all copies.
   *
   * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
   * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
   * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
   * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
   * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
   * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
   * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
   */
  
  #include "ssl_locl.h"
  
  #include "bytestring.h"
  #include "tls13_internal.h"
  
  struct tls13_buffer {
  	size_t capacity;
  	uint8_t *data;
  	size_t len;
  	size_t offset;
  };
  
  static int tls13_buffer_resize(struct tls13_buffer *buf, size_t capacity);
  
  struct tls13_buffer *
  tls13_buffer_new(size_t init_size)
  {
  	struct tls13_buffer *buf = NULL;
  
  	if ((buf = calloc(1, sizeof(struct tls13_buffer))) == NULL)
  		goto err;
  
  	if (!tls13_buffer_resize(buf, init_size))
  		goto err;
  
  	return buf;
  
   err:
  	tls13_buffer_free(buf);
  
  	return NULL;
  }
  
  void
  tls13_buffer_free(struct tls13_buffer *buf)
  {
  	if (buf == NULL)
  		return;
  
  	freezero(buf->data, buf->capacity);
  	freezero(buf, sizeof(struct tls13_buffer));
  }
  
  static int
  tls13_buffer_resize(struct tls13_buffer *buf, size_t capacity)
  {
  	uint8_t *data;
  
  	if (buf->capacity == capacity)
  		return 1;
  
  	if ((data = recallocarray(buf->data, buf->capacity, capacity, 1)) == NULL)
  		return 0;
  
  	buf->data = data;
  	buf->capacity = capacity;
  
  	return 1;
  }
  
  int
  tls13_buffer_set_data(struct tls13_buffer *buf, CBS *data)
  {
  	if (!tls13_buffer_resize(buf, CBS_len(data)))
  		return 0;
  	memcpy(buf->data, CBS_data(data), CBS_len(data));
  	return 1;
  }
  
  ssize_t
  tls13_buffer_extend(struct tls13_buffer *buf, size_t len,
      tls13_read_cb read_cb, void *cb_arg)
  {
  	ssize_t ret;
  
  	if (len == buf->len)
  		return buf->len;
  
  	if (len < buf->len)
  		return TLS13_IO_FAILURE;
  
  	if (!tls13_buffer_resize(buf, len))
  		return TLS13_IO_FAILURE;
  
  	for (;;) {
  		if ((ret = read_cb(&buf->data[buf->len],
  		    buf->capacity - buf->len, cb_arg)) <= 0)
  			return ret;
  
  		if (ret > buf->capacity - buf->len)
  			return TLS13_IO_FAILURE;
  
  		buf->len += ret;
  
  		if (buf->len == buf->capacity)
  			return buf->len;
  	}
  }
  
  void
  tls13_buffer_cbs(struct tls13_buffer *buf, CBS *cbs)
  {
  	CBS_init(cbs, buf->data, buf->len);
  }
  
  int
  tls13_buffer_finish(struct tls13_buffer *buf, uint8_t **out, size_t *out_len)
  {
  	if (out == NULL || out_len == NULL)
  		return 0;
  
  	*out = buf->data;
  	*out_len = buf->len;
  
  	buf->capacity = 0;
  	buf->data = NULL;
  	buf->len = 0;
  
  	return 1;
  }