-const char deanimate_rcs[] = "$Id: deanimate.c,v 1.12.2.1 2004/10/03 12:53:32 david__schmidt Exp $";
/*********************************************************************
*
- * File : $Source: /cvsroot/ijbswa/current/Attic/deanimate.c,v $
+ * File : $Source: /cvsroot/ijbswa/current/deanimate.c,v $
*
* Purpose : Declares functions to manipulate binary images on the
* fly. High-level functions include:
* - Deanimation of GIF images
- * - Fixup of malformed comment block in JPEG headers
- *
- * Functions declared include: gif_deanimate, buf_free,
- * buf_copy, buf_getbyte, gif_skip_data_block,
- * gif_extract_image and jpeg_inspect
*
- * Copyright : Written by and Copyright (C) 2001 - 2004 by the the
- * SourceForge Privoxy team. http://www.privoxy.org/
+ * Copyright : Written by and Copyright (C) 2001-2021 by the
+ * Privoxy team. https://www.privoxy.org/
*
* Based on the GIF file format specification (see
- * http://tronche.com/computer-graphics/gif/gif89a.html)
+ * https://tronche.com/computer-graphics/gif/gif89a.html)
* and ideas from the Image::DeAnim Perl module by
* Ken MacFarlane, <ksm+cpan@universal.dca.net>
*
- * This program is free software; you can redistribute it
+ * This program is free software; you can redistribute it
* and/or modify it under the terms of the GNU General
* Public License as published by the Free Software
* Foundation; either version 2 of the License, or (at
* or write to the Free Software Foundation, Inc., 59
* Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*
- * Revisions :
- * $Log: deanimate.c,v $
- * Revision 1.12.2.1 2004/10/03 12:53:32 david__schmidt
- * Add the ability to check jpeg images for invalid
- * lengths of comment blocks. Defensive strategy
- * against the exploit:
- * Microsoft Security Bulletin MS04-028
- * Buffer Overrun in JPEG Processing (GDI+) Could
- * Allow Code Execution (833987)
- * Enabled with +inspect-jpegs in actions files.
- *
- * Revision 1.12 2002/05/12 21:36:29 jongfoster
- * Correcting function comments
- *
- * Revision 1.11 2002/03/26 22:29:54 swa
- * we have a new homepage!
- *
- * Revision 1.10 2002/03/24 13:25:43 swa
- * name change related issues
- *
- * Revision 1.9 2002/03/13 00:27:04 jongfoster
- * Killing warnings
- *
- * Revision 1.8 2002/03/09 19:42:47 jongfoster
- * Fixing more warnings
- *
- * Revision 1.7 2002/03/08 17:46:04 jongfoster
- * Fixing int/size_t warnings
- *
- * Revision 1.6 2002/03/07 03:46:17 oes
- * Fixed compiler warnings
- *
- * Revision 1.5 2001/09/10 10:16:06 oes
- * Silenced compiler warnings
- *
- * Revision 1.4 2001/07/18 12:28:49 oes
- * - Added feature for extracting the first frame
- * to gif_deanimate
- * - Separated image buffer extension into buf_extend
- * - Extended gif deanimation to GIF87a (untested!)
- * - Cosmetics
- *
- * Revision 1.3 2001/07/15 13:57:50 jongfoster
- * Adding #includes string.h and miscutil.h
- *
- * Revision 1.2 2001/07/13 13:46:20 oes
- * Introduced GIF deanimation feature
- *
- *
**********************************************************************/
-\f
+
#include "config.h"
#include <string.h>
#include <fcntl.h>
-#include "errlog.h"
#include "project.h"
+#include "errlog.h"
#include "deanimate.h"
#include "miscutil.h"
-const char deanimate_h_rcs[] = DEANIMATE_H_VERSION;
-
/*********************************************************************
- *
+ *
* Function : buf_free
*
* Description : Safely frees a struct binbuffer
/*********************************************************************
- *
+ *
* Function : buf_extend
*
* Description : Ensure that a given binbuffer can hold a given amount
* Parameters :
* 1 : buf = Pointer to the binbuffer
* 2 : length = Desired minimum size
- *
*
- * Returns : 0 on success, 1 on failiure.
+ *
+ * Returns : 0 on success, 1 on failure.
*
*********************************************************************/
-int buf_extend(struct binbuffer *buf, size_t length)
+static int buf_extend(struct binbuffer *buf, size_t length)
{
char *newbuf;
/*********************************************************************
- *
+ *
* Function : buf_copy
*
* Description : Safely copies a given amount of bytes from one
* 2 : dst = Pointer to the destination binbuffer
* 3 : length = Number of bytes to be copied
*
- * Returns : 0 on success, 1 on failiure.
+ * Returns : 0 on success, 1 on failure.
*
*********************************************************************/
-int buf_copy(struct binbuffer *src, struct binbuffer *dst, size_t length)
+static int buf_copy(struct binbuffer *src, struct binbuffer *dst, size_t length)
{
+ /*
+ * Sanity check: Make sure the source buffer contains
+ * data and there's work to be done.
+ */
+ if (src->buffer == NULL || src->size == 0 || length == 0)
+ {
+ return 1;
+ }
/*
* Sanity check: Can't copy more data than we have
*/
- if (src->offset + length > src->size)
+ if (src->offset + length > src->size)
{
return 1;
}
/*
* Ensure that dst can hold the new data
*/
- if (buf_extend(dst, length))
+ if (buf_extend(dst, length))
{
return 1;
}
/*********************************************************************
- *
+ *
* Function : buf_getbyte
*
* Description : Safely gets a byte from a given binbuffer at a
* 1 : src = Pointer to the source binbuffer
* 2 : offset = Offset to the desired byte
*
- * Returns : The byte on success, or 0 on failiure
+ * Returns : The byte on success, or 0 on failure
*
*********************************************************************/
-unsigned char buf_getbyte(struct binbuffer *src, size_t offset)
+static unsigned char buf_getbyte(const struct binbuffer *src, size_t offset)
{
if (src->offset + offset < src->size)
{
/*********************************************************************
- *
+ *
* Function : gif_skip_data_block
*
* Description : Safely advances the offset of a given struct binbuffer
* Parameters :
* 1 : buf = Pointer to the binbuffer
*
- * Returns : 0 on success, or 1 on failiure
+ * Returns : 0 on success, or 1 on failure
*
*********************************************************************/
-int gif_skip_data_block(struct binbuffer *buf)
+static int gif_skip_data_block(struct binbuffer *buf)
{
unsigned char c;
- /*
+ /*
* Data blocks are sequences of chunks, which are headed
* by a one-byte length field, with the last chunk having
* zero length.
*/
while((c = buf_getbyte(buf, 0)) != '\0')
{
- if ((buf->offset += c + 1) >= buf->size - 1)
+ buf->offset += (size_t)c + 1;
+ if (buf->offset >= buf->size - 1)
{
return 1;
}
/*********************************************************************
- *
+ *
* Function : gif_extract_image
*
* Description : Safely extracts an image data block from a given
* struct binbuffer that contains a GIF image and whose
- * offset is positioned at the start of a data block
+ * offset is positioned at the start of a data block
* into a given destination binbuffer.
*
* Parameters :
* 1 : src = Pointer to the source binbuffer
* 2 : dst = Pointer to the destination binbuffer
*
- * Returns : 0 on success, or 1 on failiure
+ * Returns : 0 on success, or 1 on failure
*
*********************************************************************/
-int gif_extract_image(struct binbuffer *src, struct binbuffer *dst)
+static int gif_extract_image(struct binbuffer *src, struct binbuffer *dst)
{
unsigned char c;
-
+
/*
* Remember the colormap flag and copy the image head
*/
*/
if (c & 0x80)
{
- if (buf_copy(src, dst, (size_t) 3 * (1 << ((c & 0x07) + 1))))
+ int map_length = 3 * (1 << ((c & 0x07) + 1));
+ if (map_length <= 0)
+ {
+ log_error(LOG_LEVEL_DEANIMATE,
+ "colormap length = %d (%c)?", map_length, c);
+ return 1;
+ }
+ if (buf_copy(src, dst, (size_t)map_length))
{
return 1;
- }
+ }
}
if (buf_copy(src, dst, 1)) return 1;
}
/*********************************************************************
- *
+ *
* Function : gif_deanimate
*
* Description : Deanimate a given GIF image, i.e. given a GIF with
* an (optional) image block and an arbitrary number
* of image extension blocks, produce an output GIF with
* only one image block that contains the last image
- * (extenstion) block of the original.
- * Also strip Comments, Application extenstions, etc.
+ * (extension) block of the original.
+ * Also strip Comments, Application extensions, etc.
*
* Parameters :
* 1 : src = Pointer to the source binbuffer
* 3 : get_first_image = Flag: If set, get the first image
* If unset (default), get the last
*
- * Returns : 0 on success, or 1 on failiure
+ * Returns : 0 on success, or 1 on failure
*
*********************************************************************/
int gif_deanimate(struct binbuffer *src, struct binbuffer *dst, int get_first_image)
{
unsigned char c;
struct binbuffer *image;
+ int image_buffered = 0;
if (NULL == src || NULL == dst)
{
return 1;
}
+ if (src->size <= 10)
+ {
+ return 1;
+ }
c = buf_getbyte(src, 10);
/*
- * Check & copy GIF header
+ * Check & copy GIF header
*/
- if (strncmp(src->buffer, "GIF89a", 6) && strncmp(src->buffer, "GIF87a", 6))
+ if (strncmp(src->buffer, "GIF89a", 6) && strncmp(src->buffer, "GIF87a", 6))
{
return 1;
}
/*
* Look for global colormap and copy if found.
*/
- if(c & 0x80)
+ if (c & 0x80)
{
- if (buf_copy(src, dst, (size_t) 3 * (1 << ((c & 0x07) + 1))))
+ int map_length = 3 * (1 << ((c & 0x07) + 1));
+ if (map_length <= 0)
+ {
+ log_error(LOG_LEVEL_DEANIMATE,
+ "colormap length = %d (%c)?", map_length, c);
+ return 1;
+ }
+ if (buf_copy(src, dst, (size_t)map_length))
{
return 1;
}
/*
* Reserve a buffer for the current image block
*/
- if (NULL == (image = (struct binbuffer *)zalloc(sizeof(*image))))
- {
- return 1;
- }
+ image = zalloc_or_die(sizeof(*image));
/*
* Parse the GIF block by block and copy the relevant
* parts to dst
*/
- while(src->offset < src->size)
+ while (src->offset < src->size)
{
- switch(buf_getbyte(src, 0))
+ switch (buf_getbyte(src, 0))
{
/*
- * End-of-GIF Marker: Append current image and return
+ * End-of-GIF Marker: Append current image if we got
+ * one and return.
*/
case 0x3b:
+ if (image->size == 0) goto failed;
goto write;
- /*
+ /*
* Image block: Extract to current image buffer.
*/
case 0x2c:
- image->offset = 0;
+ if (image_buffered == 1)
+ {
+ /* Discard previous image. */
+ image->offset = 0;
+ image_buffered = 0;
+ }
if (gif_extract_image(src, image)) goto failed;
+ image_buffered = 1;
if (get_first_image) goto write;
continue;
switch (buf_getbyte(src, 1))
{
/*
- * Image extension: Copy extension header and image
- * to the current image buffer
+ * Image extension: Copy extension header
+ * and continue looking for new blocks.
*/
case 0xf9:
- image->offset = 0;
- if (buf_copy(src, image, 8) || buf_getbyte(src, 0) != 0x2c) goto failed;
- if (gif_extract_image(src, image)) goto failed;
- if (get_first_image) goto write;
+ if (image_buffered == 1)
+ {
+ image->offset = 0;
+ image_buffered = 0;
+ }
+ if (buf_copy(src, image, 8)) goto failed;
continue;
/*
*/
default:
goto failed;
-
+
}
} /* -END- while src */
/*
* Either we got here by goto, or because the GIF is
- * bogus and EOF was reached before an end-of-gif marker
+ * bogus and EOF was reached before an end-of-gif marker
* was found.
*/
}
-/*********************************************************************
- *
- * Function : jpeg_inspect
- *
- * Description : Checks a jpeg image for an invalid length in a
- * comment block (0xFFFE0000 or 0xFFFE0001) and
- * changes it to 0xFFFE0002. Defensive strategy
- * against the exploit:
- * Microsoft Security Bulletin MS04-028
- * Buffer Overrun in JPEG Processing (GDI+) Could
- * Allow Code Execution (833987)
- *
- * Parameters :
- * 1 : src = Pointer to the image binbuffer
- *
- * Returns : 0 on success, or 1 on failiure
- *
- *********************************************************************/
-int jpeg_inspect(struct binbuffer *src, struct binbuffer *dst)
-{
- long i;
- /*
- * We process the image using a simple finite state machine,
- * searching for byte patterns.
- */
- enum { J_INIT, /* The initial state */
- J_FF, /* Found byte 0xFF */
- J_FE, /* Found bytes 0xFF 0xFE */
- J_00, /* Found bytes 0xFF 0xFE 0x00 */
- J_DA /*
- * Found bytes 0xFF 0xDA; short-circuit to done-ness
- * since this signals the beginning end of headers.
- */
- };
- short state = J_INIT;
- unsigned char c;
-
- if (NULL == src || NULL == dst)
- {
- return 1;
- }
-
- if (buf_copy(src, dst, src->size))
- {
- return 1;
- }
-
- /* Need to search the jpg for patterns:
- * 0xFF 0xFE 0x00 0x00
- * or
- * 0xFF 0xFE 0x00 0x01
- * from beginning until:
- * 0xFF 0xDA
- * (or the end of the buffer)
- * If found, change the pattern to 0xFF 0xFE 0x00 0x02
- */
-
- for (i = 0; i < dst->size; i++)
- {
- c = dst->buffer[i];
- switch (state)
- {
- case J_INIT:
- if (c == 0xFF)
- state = J_FF;
- break;
- case J_FF:
- if (c == 0xDA)
- state = J_DA; /* End of headers - we're done with this image. */
- else if (c == 0xFE)
- state = J_FE;
- else
- state = J_INIT;
- break;
- case J_FE:
- if (c == 0x00)
- state = J_00;
- else
- state = J_INIT;
- break;
- case J_00:
- if ((c == 0x00) || (c == 0x01))
- {
- dst->buffer[i] = 2; /* Reset comment block size to 2. */
- log_error(LOG_LEVEL_INFO, "JPEG comment exploit removed.");
- /* TODO:
- * I'm unsure if we can have more than one comment block. Just in case,
- * we'll scan the rest of the header for more by going back to J_INIT
- * state. If there is no possibility of >1 comment block, we could
- * short-circuit to done-ness here.
- */
- state = J_INIT;
- }
- else
- state = J_INIT;
- break;
- default:
- break;
- }
- if (state == J_DA)
- break;
- }
-
- return 0;
-}
-
-
/*
Local Variables:
tab-width: 3
projects / privoxy.git / blobdiff