Summary

An out-of-bounds array read exists in src/decoders/pana8.cpp. The function GetDBit() can return the value 17 when no Huffman table match is found, but huff_coeff[] is declared with only 17 elements (valid indices 0-16). This results in huff_coeff[17] being accessed, triggering undefined behavior confirmed by UBSan and AddressSanitizer.

Impact

Applications that process user-supplied RW2 files, such as image editors or photo management tools using LibRaw, could crash or potentially leak process memory by opening a malicious file.

CWE: CWE-125 (Out-of-bounds Read), CWE-129 (Improper Validation of Array Index) CVSS v3.1: AV:L/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:H (~6.5 Medium)

Git commit: 777f20ae21c611a78021bd051fbbf1e71eae78f2

Affected code

File: src/decoders/pana8.cpp Function: pana8_param_t::DecodeC8()

The root cause is in GetDBit():

  uint32_t pana8_param_t::GetDBit(uint64_t a2)
  {
      for (int i = 0; i < 16; i++)
          if ((a2 & hufftable2[i]) == hufftable1[i])
              return i;
      return uint32_t((hufftable2[16] & a2) == hufftable1[16]) ^ 0x11u;
      // When comparison is false: returns 0 ^ 17 = 17
  }

The return value is then used directly as an array index with no bounds check:

  huff_index = int(GetDBit(pixbits));          // can be 17
  int32_t v37 = (huff_coeff[huff_index] >> 24) // line 250: OOB
  uint32_t hc = huff_coeff[huff_index];        // line 251: OOB
  // ... and lines 254, 273

Confirmed call chain (UBSan output) LibRaw::unpack() -> panasonicC8_load_raw() pana8.cpp:125 -> pana8_decode_loop() pana8.cpp:132 -> pana8_decode_strip() pana8.cpp:155 -> DecodeC8() pana8.cpp:250 <-- OOB triggered

UBSan errors triggered: pana8.cpp:250 index 17 out of bounds for type 'unsigned int [17]' pana8.cpp:251 index 17 out of bounds for type 'unsigned int [17]' pana8.cpp:254 index 17 out of bounds for type 'unsigned int [17]' pana8.cpp:254 shift exponent -17 is negative pana8.cpp:273 index 17 out of bounds for type 'unsigned int [17]' pana8.cpp:303 left shift of negative value -1

Reproduction

Build LibRaw with sanitizers:

  ./configure CXXFLAGS="-fsanitize=address,undefined -g -O1" \
            LDFLAGS="-fsanitize=address,undefined"
  make -j$(nproc)

Run the mutator script against any Panasonic RW2 file:

  python3 mutate_rw2.py input.rw2 mutated_pana8.rw2
  ASAN_OPTIONS=halt_on_error=0:print_stats=1 ./bin/dcraw_emu -v mutated_pana8.rw2

Patch

https://github.com/LibRaw/LibRaw/commit/02da167e0f819a37dbb7d714e87c5b40df6c5917