Decompression failures with uncompressable data #12

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claunia · 2026-01-29T20:28:55Z

claunia commented

2026-01-29 20:28:55 +00:00

Originally created by @nemequ on GitHub (Aug 24, 2015).

Seems to happen with data with a length of a power of two >= 32. 8 and 16 work, 32, 64, 128, and 256 don't. Test case:

#include <stdint.h>
#include <assert.h>

#include "enc/encode.h"
#include "dec/decode.h"

const uint8_t uncompressed[] = {
  0x01, 0x4a, 0x2d, 0x82, 0x59, 0x2f, 0xdd, 0xe6,
  0x4f, 0x69, 0x6c, 0x70, 0x13, 0x87, 0x9f, 0xe4,
  0xd3, 0xb1, 0x9a, 0x86, 0xeb, 0x31, 0xa9, 0x69,
  0x1d, 0x2b, 0x22, 0x60, 0x38, 0xaf, 0xb2, 0x27,
  0xee, 0x48, 0x9e, 0x67, 0x3d, 0x5f, 0xca, 0xfa,
  0x68, 0x74, 0x03, 0x6f, 0x03, 0x5c, 0xcb, 0x45,
  0x1c, 0xfc, 0xc1, 0x4b, 0x1d, 0xb1, 0x2b, 0x7b,
  0x87, 0xf2, 0xf4, 0xea, 0xc4, 0x34, 0x93, 0x75,
  0xb5, 0x45, 0xa0, 0x70, 0x77, 0xe9, 0xe3, 0xe3,
  0xe9, 0xf9, 0x36, 0x80, 0x2c, 0x3b, 0x19, 0xab,
  0x46, 0xe2, 0xeb, 0x16, 0xf9, 0x4c, 0xac, 0x03,
  0x42, 0x8c, 0x25, 0x3a, 0x9e, 0x68, 0xc7, 0x26,
  0xce, 0x45, 0x1f, 0x3f, 0xc6, 0x24, 0x38, 0x01,
  0xb2, 0x1a, 0x4f, 0x25, 0xd3, 0x7c, 0x5f, 0x37,
  0xbc, 0x6b, 0x3d, 0xb1, 0x1d, 0x76, 0xc5, 0xb9,
  0xae, 0xbd, 0x4c, 0x67, 0x87, 0xd9, 0xd0, 0x58,
  0xe9, 0x42, 0x4e, 0x32, 0xbf, 0x83, 0xfd, 0xad,
  0x63, 0x88, 0x7c, 0x9d, 0xd3, 0x25, 0x9e, 0xe0,
  0x44, 0x4a, 0xbf, 0x88, 0xc4, 0x46, 0x24, 0x21,
  0xf3, 0x35, 0xee, 0xa9, 0xc4, 0x6f, 0xdf, 0xe5,
  0xef, 0xc5, 0x13, 0x25, 0x3f, 0x33, 0x1e, 0x54,
  0x45, 0x79, 0xc0, 0x5e, 0x67, 0x4e, 0x7b, 0xa7,
  0xe1, 0xe8, 0x7c, 0xe6, 0x5a, 0x7a, 0x20, 0x4f,
  0x1b, 0xf2, 0xe9, 0x6a, 0x8e, 0xfc, 0x23, 0xfd,
  0x5f, 0x47, 0x24, 0x9c, 0xe4, 0xa9, 0x0c, 0x3d,
  0x8f, 0x9d, 0x81, 0x46, 0x25, 0x2d, 0x43, 0x49,
  0xe2, 0xcc, 0x98, 0x8d, 0x14, 0x2b, 0x17, 0xc2,
  0x1b, 0xd3, 0x03, 0x13, 0x8d, 0x72, 0x76, 0x96,
  0xce, 0x23, 0x93, 0xee, 0x30, 0x7a, 0xe3, 0x74,
  0xb6, 0x28, 0xc4, 0xfc, 0xb6, 0x3e, 0xf9, 0xe0,
  0x9a, 0x88, 0x86, 0x5b, 0xfc, 0xc0, 0x0b, 0xdf,
  0xa4, 0xfb, 0x79, 0x0f, 0x95, 0x12, 0xaf, 0x43
};

int main(int argc, char *argv[]) {
  uint8_t compressed[sizeof(uncompressed) + 4];
  size_t compressed_length = sizeof(compressed);
  uint8_t decompressed[sizeof(uncompressed)];
  size_t decompressed_length = sizeof(decompressed);

  {
    int result;
    brotli::BrotliParams params;
    params.quality = 11;
    params.mode = brotli::BrotliParams::MODE_GENERIC;
    params.enable_transforms = false;

    result = brotli::BrotliCompressBuffer (params,
                       sizeof(uncompressed), uncompressed,
                       &compressed_length, compressed);

    assert (result == 1);

    fprintf (stderr, "Compressed %zu bytes to %zu bytes\n", sizeof(uncompressed), compressed_length);
  }

  {
    BrotliResult result;

    result = BrotliDecompressBuffer (compressed_length, compressed,
                     &decompressed_length, decompressed);

    assert (result == BROTLI_RESULT_SUCCESS);

    fprintf (stderr, "Decompressed %zu bytes to %zu bytes\n", compressed_length, decompressed_length);
  }

  return 0;
}

Originally created by @nemequ on GitHub (Aug 24, 2015). Seems to happen with data with a length of a power of two >= 32. 8 and 16 work, 32, 64, 128, and 256 don't. Test case: ``` cpp #include <stdint.h> #include <assert.h> #include "enc/encode.h" #include "dec/decode.h" const uint8_t uncompressed[] = { 0x01, 0x4a, 0x2d, 0x82, 0x59, 0x2f, 0xdd, 0xe6, 0x4f, 0x69, 0x6c, 0x70, 0x13, 0x87, 0x9f, 0xe4, 0xd3, 0xb1, 0x9a, 0x86, 0xeb, 0x31, 0xa9, 0x69, 0x1d, 0x2b, 0x22, 0x60, 0x38, 0xaf, 0xb2, 0x27, 0xee, 0x48, 0x9e, 0x67, 0x3d, 0x5f, 0xca, 0xfa, 0x68, 0x74, 0x03, 0x6f, 0x03, 0x5c, 0xcb, 0x45, 0x1c, 0xfc, 0xc1, 0x4b, 0x1d, 0xb1, 0x2b, 0x7b, 0x87, 0xf2, 0xf4, 0xea, 0xc4, 0x34, 0x93, 0x75, 0xb5, 0x45, 0xa0, 0x70, 0x77, 0xe9, 0xe3, 0xe3, 0xe9, 0xf9, 0x36, 0x80, 0x2c, 0x3b, 0x19, 0xab, 0x46, 0xe2, 0xeb, 0x16, 0xf9, 0x4c, 0xac, 0x03, 0x42, 0x8c, 0x25, 0x3a, 0x9e, 0x68, 0xc7, 0x26, 0xce, 0x45, 0x1f, 0x3f, 0xc6, 0x24, 0x38, 0x01, 0xb2, 0x1a, 0x4f, 0x25, 0xd3, 0x7c, 0x5f, 0x37, 0xbc, 0x6b, 0x3d, 0xb1, 0x1d, 0x76, 0xc5, 0xb9, 0xae, 0xbd, 0x4c, 0x67, 0x87, 0xd9, 0xd0, 0x58, 0xe9, 0x42, 0x4e, 0x32, 0xbf, 0x83, 0xfd, 0xad, 0x63, 0x88, 0x7c, 0x9d, 0xd3, 0x25, 0x9e, 0xe0, 0x44, 0x4a, 0xbf, 0x88, 0xc4, 0x46, 0x24, 0x21, 0xf3, 0x35, 0xee, 0xa9, 0xc4, 0x6f, 0xdf, 0xe5, 0xef, 0xc5, 0x13, 0x25, 0x3f, 0x33, 0x1e, 0x54, 0x45, 0x79, 0xc0, 0x5e, 0x67, 0x4e, 0x7b, 0xa7, 0xe1, 0xe8, 0x7c, 0xe6, 0x5a, 0x7a, 0x20, 0x4f, 0x1b, 0xf2, 0xe9, 0x6a, 0x8e, 0xfc, 0x23, 0xfd, 0x5f, 0x47, 0x24, 0x9c, 0xe4, 0xa9, 0x0c, 0x3d, 0x8f, 0x9d, 0x81, 0x46, 0x25, 0x2d, 0x43, 0x49, 0xe2, 0xcc, 0x98, 0x8d, 0x14, 0x2b, 0x17, 0xc2, 0x1b, 0xd3, 0x03, 0x13, 0x8d, 0x72, 0x76, 0x96, 0xce, 0x23, 0x93, 0xee, 0x30, 0x7a, 0xe3, 0x74, 0xb6, 0x28, 0xc4, 0xfc, 0xb6, 0x3e, 0xf9, 0xe0, 0x9a, 0x88, 0x86, 0x5b, 0xfc, 0xc0, 0x0b, 0xdf, 0xa4, 0xfb, 0x79, 0x0f, 0x95, 0x12, 0xaf, 0x43 }; int main(int argc, char *argv[]) { uint8_t compressed[sizeof(uncompressed) + 4]; size_t compressed_length = sizeof(compressed); uint8_t decompressed[sizeof(uncompressed)]; size_t decompressed_length = sizeof(decompressed); { int result; brotli::BrotliParams params; params.quality = 11; params.mode = brotli::BrotliParams::MODE_GENERIC; params.enable_transforms = false; result = brotli::BrotliCompressBuffer (params, sizeof(uncompressed), uncompressed, &compressed_length, compressed); assert (result == 1); fprintf (stderr, "Compressed %zu bytes to %zu bytes\n", sizeof(uncompressed), compressed_length); } { BrotliResult result; result = BrotliDecompressBuffer (compressed_length, compressed, &decompressed_length, decompressed); assert (result == BROTLI_RESULT_SUCCESS); fprintf (stderr, "Decompressed %zu bytes to %zu bytes\n", compressed_length, decompressed_length); } return 0; } ```

claunia referenced this issue

2026-01-29 20:46:17 +00:00

[PR #12] [MERGED] Decoder code cleanup. #587

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Reference: starred/brotli#12