[M108-LTS] Fix OOB write in BuildHuffmanTable.

M108 merge issues:
  dec/vp8l_dec.c:
    - Conflicting checks before ReadHuffmanCodeLengths() return statement;
    In 114, an assignment follows the check instead of a return.
    - ReadHuffmanCodes(): Conflict after the changed huffman_tables check,
    there's an assignment in 114 instead of the setter call.

First, BuildHuffmanTable is called to check if the data is valid.
If it is and the table is not big enough, more memory is allocated.

This will make sure that valid (but unoptimized because of unbalanced
codes) streams are still decodable.

Bug: chromium:1479274
Change-Id: I31c36dbf3aa78d35ecf38706b50464fd3d375741
(cherry picked from commit 902bc91903)

CMakeLists.txt

@@ -509,19 +509,18 @@ endif()
 
 if(WEBP_BUILD_LIBWEBPMUX)
   parse_makefile_am(${CMAKE_CURRENT_SOURCE_DIR}/src/mux "WEBP_MUX_SRCS" "")
-  add_library(libwebpmux ${WEBP_MUX_SRCS})
-  target_link_libraries(libwebpmux webp)
-  target_include_directories(libwebpmux
+  add_library(webpmux ${WEBP_MUX_SRCS})
+  target_link_libraries(webpmux webp)
+  target_include_directories(webpmux
                              PRIVATE ${CMAKE_CURRENT_BINARY_DIR}
                                      ${CMAKE_CURRENT_SOURCE_DIR})
-  set_version(mux/Makefile.am libwebpmux webpmux)
-  set_target_properties(libwebpmux
+  set_version(mux/Makefile.am webpmux webpmux)
+  set_target_properties(webpmux
                         PROPERTIES PUBLIC_HEADER
                                    "${CMAKE_CURRENT_SOURCE_DIR}/src/webp/mux.h;\
 ${CMAKE_CURRENT_SOURCE_DIR}/src/webp/mux_types.h;\
 ${CMAKE_CURRENT_SOURCE_DIR}/src/webp/types.h;")
-  set_target_properties(libwebpmux PROPERTIES OUTPUT_NAME webpmux)
-  list(APPEND INSTALLED_LIBRARIES libwebpmux)
+  list(APPEND INSTALLED_LIBRARIES webpmux)
   configure_pkg_config("src/mux/libwebpmux.pc")
 endif()
 
@@ -535,7 +534,7 @@ if(WEBP_BUILD_GIF2WEBP)
                         exampleutil
                         imageioutil
                         webp
-                        libwebpmux
+                        webpmux
                         ${WEBP_DEP_GIF_LIBRARIES})
   target_include_directories(gif2webp PRIVATE ${CMAKE_CURRENT_BINARY_DIR}/src)
   install(TARGETS gif2webp RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR})
@@ -552,7 +551,7 @@ if(WEBP_BUILD_IMG2WEBP)
                         imagedec
                         imageioutil
                         webp
-                        libwebpmux)
+                        webpmux)
   target_include_directories(img2webp PRIVATE ${CMAKE_CURRENT_BINARY_DIR}/src)
   install(TARGETS img2webp RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR})
 endif()
@@ -602,10 +601,12 @@ if(WEBP_BUILD_WEBPMUX)
   # webpmux
   parse_makefile_am(${CMAKE_CURRENT_SOURCE_DIR}/examples "WEBPMUX_SRCS"
                     "webpmux")
-  add_executable(webpmux ${WEBPMUX_SRCS})
-  target_link_libraries(webpmux exampleutil imageioutil libwebpmux webp)
-  target_include_directories(webpmux PRIVATE ${CMAKE_CURRENT_BINARY_DIR}/src)
-  install(TARGETS webpmux RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR})
+  add_executable(webpmux_app ${WEBPMUX_SRCS})
+  set_target_properties(webpmux_app PROPERTIES OUTPUT_NAME webpmux)
+  target_link_libraries(webpmux_app exampleutil imageioutil webpmux webp)
+  target_include_directories(webpmux_app
+                             PRIVATE ${CMAKE_CURRENT_BINARY_DIR}/src)
+  install(TARGETS webpmux_app RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR})
 endif()
 
 if(WEBP_BUILD_EXTRAS)
@@ -737,10 +738,6 @@ write_basic_package_version_file(
 
 # Create the Config file.
 include(CMakePackageConfigHelpers)
-# Fix libwebpmux reference. The target name libwebpmux is used for
-# compatibility purposes, but the library mentioned in WebPConfig.cmake should
-# be the unprefixed version.
-list(TRANSFORM INSTALLED_LIBRARIES REPLACE "libwebpmux" "webpmux")
 configure_package_config_file(
   ${CMAKE_CURRENT_SOURCE_DIR}/cmake/WebPConfig.cmake.in
   ${CMAKE_CURRENT_BINARY_DIR}/WebPConfig.cmake

ChangeLog

@@ -1,9 +1,3 @@
-980d2488 update NEWS
-9fde8127 bump version to 1.2.4
-e626925c lossless: fix crunch mode w/WEBP_REDUCE_SIZE
-bfad7ab5 CMakeLists.txt: correct libwebpmux name in WebPConfig.cmake
-c2e3fd30 Revert "cmake: fix webpmux lib name for cmake linking"
-3c4a0fbf update ChangeLog (tag: v1.2.3)
 56a480e8 dsp/cpu.h: add missing extern "C"
 62b45bdd update ChangeLog (tag: v1.2.3-rc1)
 8764ec7a Merge changes Idb037953,Id582e395 into 1.2.3

NEWS

@@ -1,9 +1,3 @@
-- 8/4/2022: version 1.2.4
-  This is a binary compatible release.
-  * restore CMake libwebpmux target name for compatibility with 1.2.2 (#575)
-  * fix lossless crunch mode encoding with WEBP_REDUCE_SIZE
-    (chromium: #1345547, #1345595, #1345772, #1345804)
-
 - 6/30/2022: version 1.2.3
   This is a binary compatible release.
   * security fix for lossless encoder (#565, chromium:1313709)

README.md

@@ -7,7 +7,7 @@
       \__\__/\____/\_____/__/ ____  ___
             / _/ /    \    \ /  _ \/ _/
            /  \_/   / /   \ \   __/  \__
-           \____/____/\_____/_____/____/v1.2.4
+           \____/____/\_____/_____/____/v1.2.3
 ```
 
 WebP codec is a library to encode and decode images in WebP format. This package

configure.ac

@@ -1,4 +1,4 @@
-AC_INIT([libwebp], [1.2.4],
+AC_INIT([libwebp], [1.2.3],
         [https://bugs.chromium.org/p/webp],,
         [https://developers.google.com/speed/webp])
 AC_CANONICAL_HOST

doc/webp-lossless-bitstream-spec.txt

@@ -634,7 +634,7 @@ We use image data in five different roles:
      [Color Indexing Transform](#color-indexing-transform). This is stored as an
      image of width `color_table_size` and height `1`.
 
-### 4.2 Encoding of Image data
+### 4.2 Encoding of Image Data
 
 The encoding of image data is independent of its role.
 

extras/extras.c

@@ -19,7 +19,7 @@
 
 #define XTRA_MAJ_VERSION 1
 #define XTRA_MIN_VERSION 2
-#define XTRA_REV_VERSION 4
+#define XTRA_REV_VERSION 3
 
 //------------------------------------------------------------------------------
 

src/Makefile.am

@@ -36,7 +36,7 @@ libwebp_la_LIBADD += utils/libwebputils.la
 # other than the ones listed on the command line, i.e., after linking, it will
 # not have unresolved symbols. Some platforms (Windows among them) require all
 # symbols in shared libraries to be resolved at library creation.
-libwebp_la_LDFLAGS = -no-undefined -version-info 8:5:1
+libwebp_la_LDFLAGS = -no-undefined -version-info 8:4:1
 libwebpincludedir = $(includedir)/webp
 pkgconfig_DATA = libwebp.pc
 
@@ -48,7 +48,7 @@ if BUILD_LIBWEBPDECODER
   libwebpdecoder_la_LIBADD += dsp/libwebpdspdecode.la
   libwebpdecoder_la_LIBADD += utils/libwebputilsdecode.la
 
-  libwebpdecoder_la_LDFLAGS = -no-undefined -version-info 4:5:1
+  libwebpdecoder_la_LDFLAGS = -no-undefined -version-info 4:4:1
   pkgconfig_DATA += libwebpdecoder.pc
 endif
 

src/dec/vp8i_dec.h

@@ -32,7 +32,7 @@ extern "C" {
 // version numbers
 #define DEC_MAJ_VERSION 1
 #define DEC_MIN_VERSION 2
-#define DEC_REV_VERSION 4
+#define DEC_REV_VERSION 3
 
 // YUV-cache parameters. Cache is 32-bytes wide (= one cacheline).
 // Constraints are: We need to store one 16x16 block of luma samples (y),

src/dec/vp8l_dec.c

@@ -253,11 +253,11 @@ static int ReadHuffmanCodeLengths(
   int symbol;
   int max_symbol;
   int prev_code_len = DEFAULT_CODE_LENGTH;
-  HuffmanCode table[1 << LENGTHS_TABLE_BITS];
+  HuffmanTables tables;
 
-  if (!VP8LBuildHuffmanTable(table, LENGTHS_TABLE_BITS,
-                             code_length_code_lengths,
-                             NUM_CODE_LENGTH_CODES)) {
+  if (!VP8LHuffmanTablesAllocate(1 << LENGTHS_TABLE_BITS, &tables) ||
+      !VP8LBuildHuffmanTable(&tables, LENGTHS_TABLE_BITS,
+                             code_length_code_lengths, NUM_CODE_LENGTH_CODES)) {
     goto End;
   }
 
@@ -277,7 +277,7 @@ static int ReadHuffmanCodeLengths(
     int code_len;
     if (max_symbol-- == 0) break;
     VP8LFillBitWindow(br);
-    p = &table[VP8LPrefetchBits(br) & LENGTHS_TABLE_MASK];
+    p = &tables.curr_segment->start[VP8LPrefetchBits(br) & LENGTHS_TABLE_MASK];
     VP8LSetBitPos(br, br->bit_pos_ + p->bits);
     code_len = p->value;
     if (code_len < kCodeLengthLiterals) {
@@ -300,6 +300,7 @@ static int ReadHuffmanCodeLengths(
   ok = 1;
 
  End:
+  VP8LHuffmanTablesDeallocate(&tables);
   if (!ok) dec->status_ = VP8_STATUS_BITSTREAM_ERROR;
   return ok;
 }
@@ -307,7 +308,8 @@ static int ReadHuffmanCodeLengths(
 // 'code_lengths' is pre-allocated temporary buffer, used for creating Huffman
 // tree.
 static int ReadHuffmanCode(int alphabet_size, VP8LDecoder* const dec,
-                           int* const code_lengths, HuffmanCode* const table) {
+                           int* const code_lengths,
+                           HuffmanTables* const table) {
   int ok = 0;
   int size = 0;
   VP8LBitReader* const br = &dec->br_;
@@ -362,8 +364,7 @@ static int ReadHuffmanCodes(VP8LDecoder* const dec, int xsize, int ysize,
   VP8LMetadata* const hdr = &dec->hdr_;
   uint32_t* huffman_image = NULL;
   HTreeGroup* htree_groups = NULL;
-  HuffmanCode* huffman_tables = NULL;
-  HuffmanCode* huffman_table = NULL;
+  HuffmanTables* huffman_tables = &hdr->huffman_tables_;
   int num_htree_groups = 1;
   int num_htree_groups_max = 1;
   int max_alphabet_size = 0;
@@ -372,6 +373,10 @@ static int ReadHuffmanCodes(VP8LDecoder* const dec, int xsize, int ysize,
   int* mapping = NULL;
   int ok = 0;
 
+  // Check the table has been 0 initialized (through InitMetadata).
+  assert(huffman_tables->root.start == NULL);
+  assert(huffman_tables->curr_segment == NULL);
+
   if (allow_recursion && VP8LReadBits(br, 1)) {
     // use meta Huffman codes.
     const int huffman_precision = VP8LReadBits(br, 3) + 2;
@@ -434,16 +439,15 @@ static int ReadHuffmanCodes(VP8LDecoder* const dec, int xsize, int ysize,
 
   code_lengths = (int*)WebPSafeCalloc((uint64_t)max_alphabet_size,
                                       sizeof(*code_lengths));
-  huffman_tables = (HuffmanCode*)WebPSafeMalloc(num_htree_groups * table_size,
-                                                sizeof(*huffman_tables));
   htree_groups = VP8LHtreeGroupsNew(num_htree_groups);
 
-  if (htree_groups == NULL || code_lengths == NULL || huffman_tables == NULL) {
+  if (htree_groups == NULL || code_lengths == NULL ||
+      !VP8LHuffmanTablesAllocate(num_htree_groups * table_size,
+                                 huffman_tables)) {
     dec->status_ = VP8_STATUS_OUT_OF_MEMORY;
     goto Error;
   }
 
-  huffman_table = huffman_tables;
   for (i = 0; i < num_htree_groups_max; ++i) {
     // If the index "i" is unused in the Huffman image, just make sure the
     // coefficients are valid but do not store them.
@@ -468,19 +472,20 @@ static int ReadHuffmanCodes(VP8LDecoder* const dec, int xsize, int ysize,
       int max_bits = 0;
       for (j = 0; j < HUFFMAN_CODES_PER_META_CODE; ++j) {
         int alphabet_size = kAlphabetSize[j];
-        htrees[j] = huffman_table;
         if (j == 0 && color_cache_bits > 0) {
           alphabet_size += (1 << color_cache_bits);
         }
-        size = ReadHuffmanCode(alphabet_size, dec, code_lengths, huffman_table);
+        size =
+            ReadHuffmanCode(alphabet_size, dec, code_lengths, huffman_tables);
+        htrees[j] = huffman_tables->curr_segment->curr_table;
         if (size == 0) {
           goto Error;
         }
         if (is_trivial_literal && kLiteralMap[j] == 1) {
-          is_trivial_literal = (huffman_table->bits == 0);
+          is_trivial_literal = (htrees[j]->bits == 0);
         }
-        total_size += huffman_table->bits;
-        huffman_table += size;
+        total_size += htrees[j]->bits;
+        huffman_tables->curr_segment->curr_table += size;
         if (j <= ALPHA) {
           int local_max_bits = code_lengths[0];
           int k;
@@ -515,14 +520,13 @@ static int ReadHuffmanCodes(VP8LDecoder* const dec, int xsize, int ysize,
   hdr->huffman_image_ = huffman_image;
   hdr->num_htree_groups_ = num_htree_groups;
   hdr->htree_groups_ = htree_groups;
-  hdr->huffman_tables_ = huffman_tables;
 
  Error:
   WebPSafeFree(code_lengths);
   WebPSafeFree(mapping);
   if (!ok) {
     WebPSafeFree(huffman_image);
-    WebPSafeFree(huffman_tables);
+    VP8LHuffmanTablesDeallocate(huffman_tables);
     VP8LHtreeGroupsFree(htree_groups);
   }
   return ok;
@@ -1358,7 +1362,7 @@ static void ClearMetadata(VP8LMetadata* const hdr) {
   assert(hdr != NULL);
 
   WebPSafeFree(hdr->huffman_image_);
-  WebPSafeFree(hdr->huffman_tables_);
+  VP8LHuffmanTablesDeallocate(&hdr->huffman_tables_);
   VP8LHtreeGroupsFree(hdr->htree_groups_);
   VP8LColorCacheClear(&hdr->color_cache_);
   VP8LColorCacheClear(&hdr->saved_color_cache_);
@@ -1673,7 +1677,7 @@ int VP8LDecodeImage(VP8LDecoder* const dec) {
 
   if (dec == NULL) return 0;
 
-  assert(dec->hdr_.huffman_tables_ != NULL);
+  assert(dec->hdr_.huffman_tables_.root.start != NULL);
   assert(dec->hdr_.htree_groups_ != NULL);
   assert(dec->hdr_.num_htree_groups_ > 0);
 

src/dec/vp8li_dec.h

@@ -51,7 +51,7 @@ typedef struct {
   uint32_t*       huffman_image_;
   int             num_htree_groups_;
   HTreeGroup*     htree_groups_;
-  HuffmanCode*    huffman_tables_;
+  HuffmanTables   huffman_tables_;
 } VP8LMetadata;
 
 typedef struct VP8LDecoder VP8LDecoder;

src/demux/Makefile.am

@@ -13,6 +13,6 @@ noinst_HEADERS =
 noinst_HEADERS += ../webp/format_constants.h
 
 libwebpdemux_la_LIBADD = ../libwebp.la
-libwebpdemux_la_LDFLAGS = -no-undefined -version-info 2:11:0
+libwebpdemux_la_LDFLAGS = -no-undefined -version-info 2:10:0
 libwebpdemuxincludedir = $(includedir)/webp
 pkgconfig_DATA = libwebpdemux.pc

src/demux/demux.c

@@ -25,7 +25,7 @@
 
 #define DMUX_MAJ_VERSION 1
 #define DMUX_MIN_VERSION 2
-#define DMUX_REV_VERSION 4
+#define DMUX_REV_VERSION 3
 
 typedef struct {
   size_t start_;        // start location of the data

src/demux/libwebpdemux.rc

@@ -6,8 +6,8 @@
 LANGUAGE LANG_ENGLISH, SUBLANG_ENGLISH_US
 
 VS_VERSION_INFO VERSIONINFO
- FILEVERSION 1,0,2,4
- PRODUCTVERSION 1,0,2,4
+ FILEVERSION 1,0,2,3
+ PRODUCTVERSION 1,0,2,3
  FILEFLAGSMASK 0x3fL
 #ifdef _DEBUG
  FILEFLAGS 0x1L
@@ -24,12 +24,12 @@ BEGIN
         BEGIN
             VALUE "CompanyName", "Google, Inc."
             VALUE "FileDescription", "libwebpdemux DLL"
-            VALUE "FileVersion", "1.2.4"
+            VALUE "FileVersion", "1.2.3"
             VALUE "InternalName", "libwebpdemux.dll"
             VALUE "LegalCopyright", "Copyright (C) 2022"
             VALUE "OriginalFilename", "libwebpdemux.dll"
             VALUE "ProductName", "WebP Image Demuxer"
-            VALUE "ProductVersion", "1.2.4"
+            VALUE "ProductVersion", "1.2.3"
         END
     END
     BLOCK "VarFileInfo"

src/enc/vp8i_enc.h

@@ -32,7 +32,7 @@ extern "C" {
 // version numbers
 #define ENC_MAJ_VERSION 1
 #define ENC_MIN_VERSION 2
-#define ENC_REV_VERSION 4
+#define ENC_REV_VERSION 3
 
 enum { MAX_LF_LEVELS = 64,       // Maximum loop filter level
        MAX_VARIABLE_LEVEL = 67,  // last (inclusive) level with variable cost

src/libwebp.rc

@@ -6,8 +6,8 @@
 LANGUAGE LANG_ENGLISH, SUBLANG_ENGLISH_US
 
 VS_VERSION_INFO VERSIONINFO
- FILEVERSION 1,0,2,4
- PRODUCTVERSION 1,0,2,4
+ FILEVERSION 1,0,2,3
+ PRODUCTVERSION 1,0,2,3
  FILEFLAGSMASK 0x3fL
 #ifdef _DEBUG
  FILEFLAGS 0x1L
@@ -24,12 +24,12 @@ BEGIN
         BEGIN
             VALUE "CompanyName", "Google, Inc."
             VALUE "FileDescription", "libwebp DLL"
-            VALUE "FileVersion", "1.2.4"
+            VALUE "FileVersion", "1.2.3"
             VALUE "InternalName", "libwebp.dll"
             VALUE "LegalCopyright", "Copyright (C) 2022"
             VALUE "OriginalFilename", "libwebp.dll"
             VALUE "ProductName", "WebP Image Codec"
-            VALUE "ProductVersion", "1.2.4"
+            VALUE "ProductVersion", "1.2.3"
         END
     END
     BLOCK "VarFileInfo"

src/libwebpdecoder.rc

@@ -6,8 +6,8 @@
 LANGUAGE LANG_ENGLISH, SUBLANG_ENGLISH_US
 
 VS_VERSION_INFO VERSIONINFO
- FILEVERSION 1,0,2,4
- PRODUCTVERSION 1,0,2,4
+ FILEVERSION 1,0,2,3
+ PRODUCTVERSION 1,0,2,3
  FILEFLAGSMASK 0x3fL
 #ifdef _DEBUG
  FILEFLAGS 0x1L
@@ -24,12 +24,12 @@ BEGIN
         BEGIN
             VALUE "CompanyName", "Google, Inc."
             VALUE "FileDescription", "libwebpdecoder DLL"
-            VALUE "FileVersion", "1.2.4"
+            VALUE "FileVersion", "1.2.3"
             VALUE "InternalName", "libwebpdecoder.dll"
             VALUE "LegalCopyright", "Copyright (C) 2022"
             VALUE "OriginalFilename", "libwebpdecoder.dll"
             VALUE "ProductName", "WebP Image Decoder"
-            VALUE "ProductVersion", "1.2.4"
+            VALUE "ProductVersion", "1.2.3"
         END
     END
     BLOCK "VarFileInfo"

src/mux/Makefile.am

@@ -17,6 +17,6 @@ noinst_HEADERS =
 noinst_HEADERS += ../webp/format_constants.h
 
 libwebpmux_la_LIBADD = ../libwebp.la
-libwebpmux_la_LDFLAGS = -no-undefined -version-info 3:10:0 -lm
+libwebpmux_la_LDFLAGS = -no-undefined -version-info 3:9:0 -lm
 libwebpmuxincludedir = $(includedir)/webp
 pkgconfig_DATA = libwebpmux.pc

src/mux/libwebpmux.rc

@@ -6,8 +6,8 @@
 LANGUAGE LANG_ENGLISH, SUBLANG_ENGLISH_US
 
 VS_VERSION_INFO VERSIONINFO
- FILEVERSION 1,0,2,4
- PRODUCTVERSION 1,0,2,4
+ FILEVERSION 1,0,2,3
+ PRODUCTVERSION 1,0,2,3
  FILEFLAGSMASK 0x3fL
 #ifdef _DEBUG
  FILEFLAGS 0x1L
@@ -24,12 +24,12 @@ BEGIN
         BEGIN
             VALUE "CompanyName", "Google, Inc."
             VALUE "FileDescription", "libwebpmux DLL"
-            VALUE "FileVersion", "1.2.4"
+            VALUE "FileVersion", "1.2.3"
             VALUE "InternalName", "libwebpmux.dll"
             VALUE "LegalCopyright", "Copyright (C) 2022"
             VALUE "OriginalFilename", "libwebpmux.dll"
             VALUE "ProductName", "WebP Image Muxer"
-            VALUE "ProductVersion", "1.2.4"
+            VALUE "ProductVersion", "1.2.3"
         END
     END
     BLOCK "VarFileInfo"

src/mux/muxi.h

@@ -29,7 +29,7 @@ extern "C" {
 
 #define MUX_MAJ_VERSION 1
 #define MUX_MIN_VERSION 2
-#define MUX_REV_VERSION 4
+#define MUX_REV_VERSION 3
 
 // Chunk object.
 typedef struct WebPChunk WebPChunk;

src/utils/huffman_utils.c

@@ -177,21 +177,24 @@ static int BuildHuffmanTable(HuffmanCode* const root_table, int root_bits,
       if (num_open < 0) {
         return 0;
       }
-      if (root_table == NULL) continue;
       for (; count[len] > 0; --count[len]) {
         HuffmanCode code;
         if ((key & mask) != low) {
-          table += table_size;
+          if (root_table != NULL) table += table_size;
           table_bits = NextTableBitSize(count, len, root_bits);
           table_size = 1 << table_bits;
           total_size += table_size;
           low = key & mask;
-          root_table[low].bits = (uint8_t)(table_bits + root_bits);
-          root_table[low].value = (uint16_t)((table - root_table) - low);
+          if (root_table != NULL) {
+            root_table[low].bits = (uint8_t)(table_bits + root_bits);
+            root_table[low].value = (uint16_t)((table - root_table) - low);
+          }
+        }
+        if (root_table != NULL) {
+          code.bits = (uint8_t)(len - root_bits);
+          code.value = (uint16_t)sorted[symbol++];
+          ReplicateValue(&table[key >> root_bits], step, table_size, code);
         }
-        code.bits = (uint8_t)(len - root_bits);
-        code.value = (uint16_t)sorted[symbol++];
-        ReplicateValue(&table[key >> root_bits], step, table_size, code);
         key = GetNextKey(key, len);
       }
     }
@@ -211,25 +214,83 @@ static int BuildHuffmanTable(HuffmanCode* const root_table, int root_bits,
   ((1 << MAX_CACHE_BITS) + NUM_LITERAL_CODES + NUM_LENGTH_CODES)
 // Cut-off value for switching between heap and stack allocation.
 #define SORTED_SIZE_CUTOFF 512
-int VP8LBuildHuffmanTable(HuffmanCode* const root_table, int root_bits,
+int VP8LBuildHuffmanTable(HuffmanTables* const root_table, int root_bits,
                           const int code_lengths[], int code_lengths_size) {
-  int total_size;
+  const int total_size =
+      BuildHuffmanTable(NULL, root_bits, code_lengths, code_lengths_size, NULL);
   assert(code_lengths_size <= MAX_CODE_LENGTHS_SIZE);
-  if (root_table == NULL) {
-    total_size = BuildHuffmanTable(NULL, root_bits,
-                                   code_lengths, code_lengths_size, NULL);
-  } else if (code_lengths_size <= SORTED_SIZE_CUTOFF) {
+  if (total_size == 0 || root_table == NULL) return total_size;
+
+  if (root_table->curr_segment->curr_table + total_size >=
+      root_table->curr_segment->start + root_table->curr_segment->size) {
+    // If 'root_table' does not have enough memory, allocate a new segment.
+    // The available part of root_table->curr_segment is left unused because we
+    // need a contiguous buffer.
+    const int segment_size = root_table->curr_segment->size;
+    struct HuffmanTablesSegment* next =
+        (HuffmanTablesSegment*)WebPSafeMalloc(1, sizeof(*next));
+    if (next == NULL) return 0;
+    // Fill the new segment.
+    // We need at least 'total_size' but if that value is small, it is better to
+    // allocate a big chunk to prevent more allocations later. 'segment_size' is
+    // therefore chosen (any other arbitrary value could be chosen).
+    next->size = total_size > segment_size ? total_size : segment_size;
+    next->start =
+        (HuffmanCode*)WebPSafeMalloc(next->size, sizeof(*next->start));
+    if (next->start == NULL) {
+      WebPSafeFree(next);
+      return 0;
+    }
+    next->curr_table = next->start;
+    next->next = NULL;
+    // Point to the new segment.
+    root_table->curr_segment->next = next;
+    root_table->curr_segment = next;
+  }
+  if (code_lengths_size <= SORTED_SIZE_CUTOFF) {
     // use local stack-allocated array.
     uint16_t sorted[SORTED_SIZE_CUTOFF];
-    total_size = BuildHuffmanTable(root_table, root_bits,
-                                   code_lengths, code_lengths_size, sorted);
-  } else {   // rare case. Use heap allocation.
+    BuildHuffmanTable(root_table->curr_segment->curr_table, root_bits,
+                      code_lengths, code_lengths_size, sorted);
+  } else {  // rare case. Use heap allocation.
     uint16_t* const sorted =
         (uint16_t*)WebPSafeMalloc(code_lengths_size, sizeof(*sorted));
     if (sorted == NULL) return 0;
-    total_size = BuildHuffmanTable(root_table, root_bits,
-                                   code_lengths, code_lengths_size, sorted);
+    BuildHuffmanTable(root_table->curr_segment->curr_table, root_bits,
+                      code_lengths, code_lengths_size, sorted);
     WebPSafeFree(sorted);
   }
   return total_size;
 }
+
+int VP8LHuffmanTablesAllocate(int size, HuffmanTables* huffman_tables) {
+  // Have 'segment' point to the first segment for now, 'root'.
+  HuffmanTablesSegment* const root = &huffman_tables->root;
+  huffman_tables->curr_segment = root;
+  // Allocate root.
+  root->start = (HuffmanCode*)WebPSafeMalloc(size, sizeof(*root->start));
+  if (root->start == NULL) return 0;
+  root->curr_table = root->start;
+  root->next = NULL;
+  root->size = size;
+  return 1;
+}
+
+void VP8LHuffmanTablesDeallocate(HuffmanTables* const huffman_tables) {
+  HuffmanTablesSegment *current, *next;
+  if (huffman_tables == NULL) return;
+  // Free the root node.
+  current = &huffman_tables->root;
+  next = current->next;
+  WebPSafeFree(current->start);
+  current->start = NULL;
+  current->next = NULL;
+  current = next;
+  // Free the following nodes.
+  while (current != NULL) {
+    next = current->next;
+    WebPSafeFree(current->start);
+    WebPSafeFree(current);
+    current = next;
+  }
+}

src/utils/huffman_utils.h

@@ -43,6 +43,29 @@ typedef struct {
                     // or non-literal symbol otherwise
 } HuffmanCode32;
 
+// Contiguous memory segment of HuffmanCodes.
+typedef struct HuffmanTablesSegment {
+  HuffmanCode* start;
+  // Pointer to where we are writing into the segment. Starts at 'start' and
+  // cannot go beyond 'start' + 'size'.
+  HuffmanCode* curr_table;
+  // Pointer to the next segment in the chain.
+  struct HuffmanTablesSegment* next;
+  int size;
+} HuffmanTablesSegment;
+
+// Chained memory segments of HuffmanCodes.
+typedef struct HuffmanTables {
+  HuffmanTablesSegment root;
+  // Currently processed segment. At first, this is 'root'.
+  HuffmanTablesSegment* curr_segment;
+} HuffmanTables;
+
+// Allocates a HuffmanTables with 'size' contiguous HuffmanCodes. Returns 0 on
+// memory allocation error, 1 otherwise.
+int VP8LHuffmanTablesAllocate(int size, HuffmanTables* huffman_tables);
+void VP8LHuffmanTablesDeallocate(HuffmanTables* const huffman_tables);
+
 #define HUFFMAN_PACKED_BITS 6
 #define HUFFMAN_PACKED_TABLE_SIZE (1u << HUFFMAN_PACKED_BITS)
 
@@ -78,9 +101,7 @@ void VP8LHtreeGroupsFree(HTreeGroup* const htree_groups);
 // the huffman table.
 // Returns built table size or 0 in case of error (invalid tree or
 // memory error).
-// If root_table is NULL, it returns 0 if a lookup cannot be built, something
-// > 0 otherwise (but not the table size).
-int VP8LBuildHuffmanTable(HuffmanCode* const root_table, int root_bits,
+int VP8LBuildHuffmanTable(HuffmanTables* const root_table, int root_bits,
                           const int code_lengths[], int code_lengths_size);
 
 #ifdef __cplusplus