Make sure all values here are initialized

aaaaaa123456789 · Jan 10, 2022 · 3753b40 · 3753b40
1 parent 3395882
commit 3753b40
Show file tree

Hide file tree

Showing 2 changed files with 7 additions and 4 deletions.
diff --git a/docs/changelog.md b/docs/changelog.md
@@ -6,7 +6,7 @@ Note: releases are listed from latest to oldest.
 
 - New functions: `plum_load_image_limited`, `plum_check_limited_image_size`, `plum_append_metadata`
 - Added a missing check for an extremely unlikely memory allocation failure
-- Fixed some BMP encoding bugs that could arise under unusual circumstances
+- Fixed some BMP and JPEG encoding bugs that could arise under unusual circumstances
 - Fixed BMP decoder to accept images that are exactly `0x7fffffff` pixels tall or wide
 - Fixed palette generation for images with many similar colors
 - Updated the tutorial to use `plum_append_metadata` where relevant

diff --git a/src/jpegarithmetic.c b/src/jpegarithmetic.c
@@ -155,8 +155,11 @@ void decompress_JPEG_arithmetic_lossless_scan (struct context * context, struct
                                                size_t rowunits, const struct JPEG_component_info * components, const size_t * offsets, unsigned char predictor,
                                                unsigned precision) {
   size_t p, restart_interval;
+  uint8_t scancomponents[4] = {0, 0, 0, 0};
+  for (p = 0; state -> MCU[p] != MCU_END_LIST; p ++) if (state -> MCU[p] < 4) scancomponents[state -> MCU[p]] = 1;
   uint16_t * rowdifferences[4] = {0};
-  for (p = 0; p < 4; p ++) rowdifferences[p] = ctxmalloc(context, sizeof **rowdifferences * rowunits * ((state -> component_count > 1) ? components[p].scaleH : 1));
+  for (p = 0; p < 4; p ++) if (scancomponents[p])
+    rowdifferences[p] = ctxmalloc(context, sizeof **rowdifferences * rowunits * ((state -> component_count > 1) ? components[p].scaleH : 1));
   for (restart_interval = 0; restart_interval <= state -> restart_count; restart_interval ++) {
     size_t units = (restart_interval == state -> restart_count) ? state -> last_size : state -> restart_size;
     if (!units) break;
@@ -170,8 +173,8 @@ void decompress_JPEG_arithmetic_lossless_scan (struct context * context, struct
     unsigned char conditioning, bits = 0;
     initialize_JPEG_arithmetic_counters(context, &offset, &remaining, &current);
     signed char indexes[4][158] = {0};
-    for (p = 0; p < 4; p ++) for (x = 0; x < (rowunits * ((state -> component_count > 1) ? components[p].scaleH : 1)); x ++)
-      rowdifferences[p][x] = 0;
+    for (p = 0; p < 4; p ++) if (scancomponents[p])
+      for (x = 0; x < (rowunits * ((state -> component_count > 1) ? components[p].scaleH : 1)); x ++) rowdifferences[p][x] = 0;
     uint16_t coldifferences[4][4] = {0};
     while (units --) {
       for (decodepos = state -> MCU; *decodepos != MCU_END_LIST; decodepos ++) switch (*decodepos) {