Fix some harmless potential overflows.

Change-Id: Iebf78971f43b795d90e05316540ce00ba79443dc

src/dec/webp_dec.c

@@ -164,7 +164,7 @@ static VP8StatusCode ParseOptionalChunks(
     size_t* WEBP_SINGLE const alpha_size) {
   size_t buf_size;
   const uint8_t* WEBP_COUNTED_BY(buf_size) buf;
-  uint32_t total_size = TAG_SIZE +           // "WEBP".
+  uint64_t total_size = TAG_SIZE +           // "WEBP".
                         CHUNK_HEADER_SIZE +  // "VP8Xnnnn".
                         VP8X_CHUNK_SIZE;     // data.
   assert(data != NULL);

src/dsp/rescaler.c

@@ -28,9 +28,8 @@
 
 //------------------------------------------------------------------------------
 // Row import
-
-void WebPRescalerImportRowExpand_C(WebPRescaler* WEBP_RESTRICT const wrk,
-                                   const uint8_t* WEBP_RESTRICT src) {
+WEBP_UBSAN_IGNORE_UNSIGNED_OVERFLOW void WebPRescalerImportRowExpand_C(
+    WebPRescaler* WEBP_RESTRICT const wrk, const uint8_t* WEBP_RESTRICT src) {
   const int x_stride = wrk->num_channels;
   const int x_out_max = wrk->dst_width * wrk->num_channels;
   int channel;

src/enc/quant_enc.c

@@ -623,7 +623,7 @@ static int TrellisQuantizeBlock(const VP8Encoder* WEBP_RESTRICT const enc,
     // note: it's important to take sign of the _original_ coeff,
     // so we don't have to consider level < 0 afterward.
     const int sign = (in[j] < 0);
-    const uint32_t coeff0 = (sign ? -in[j] : in[j]) + mtx->sharpen[j];
+    const int32_t coeff0 = (sign ? -in[j] : in[j]) + mtx->sharpen[j];
     int level0 = QUANTDIV(coeff0, iQ, B);
     int thresh_level = QUANTDIV(coeff0, iQ, BIAS(0x80));
     if (thresh_level > MAX_LEVEL) thresh_level = MAX_LEVEL;
@@ -663,7 +663,7 @@ static int TrellisQuantizeBlock(const VP8Encoder* WEBP_RESTRICT const enc,
         // Compute delta_error = how much coding this level will
         // subtract to max_error as distortion.
         // Here, distortion = sum of (|coeff_i| - level_i * Q_i)^2
-        const int new_error = coeff0 - level * Q;
+        const int new_error = coeff0 - level * (int32_t)Q;
         const int delta_error =
             kWeightTrellis[j] * (new_error * new_error - coeff0 * coeff0);
         base_score = RDScoreTrellis(lambda, 0, delta_error);

src/utils/random_utils.h

@@ -16,6 +16,7 @@
 
 #include <assert.h>
 
+#include "src/dsp/cpu.h"
 #include "src/utils/bounds_safety.h"
 #include "src/webp/types.h"
 
@@ -40,8 +41,8 @@ void VP8InitRandom(VP8Random* const rg, float dithering);
 // Returns a centered pseudo-random number with 'num_bits' amplitude.
 // (uses D.Knuth's Difference-based random generator).
 // 'amp' is in VP8_RANDOM_DITHER_FIX fixed-point precision.
-static WEBP_INLINE int VP8RandomBits2(VP8Random* const rg, int num_bits,
-                                      int amp) {
+static WEBP_UBSAN_IGNORE_UNSIGNED_OVERFLOW WEBP_INLINE int VP8RandomBits2(
+    VP8Random* const rg, int num_bits, int amp) {
   int diff;
   assert(num_bits + VP8_RANDOM_DITHER_FIX <= 31);
   diff = rg->tab[rg->index1] - rg->tab[rg->index2];

src/utils/rescaler_utils.c

@@ -93,6 +93,10 @@ int WebPRescalerGetScaledDimensions(int src_width, int src_height,
                                     int* const scaled_height) {
   assert(scaled_width != NULL);
   assert(scaled_height != NULL);
+  if (src_width < 0 || src_height < 0 || *scaled_width < 0 ||
+      *scaled_height < 0) {
+    return 0;
+  }
   {
     int width = *scaled_width;
     int height = *scaled_height;