Fixes: skyconv buffer overflow, DLL copy on non-windows build, correct gfx directory on Linux

Makefile

@@ -971,13 +971,15 @@ else
 $(EXE): $(O_FILES) $(MIO0_FILES:.mio0=.o) $(ULTRA_O_FILES) $(GODDARD_O_FILES)
 	$(LD) -L $(BUILD_DIR) -o $@ $(O_FILES) $(ULTRA_O_FILES) $(GODDARD_O_FILES) $(LDFLAGS)
 
-  # Copying the dynamically linked DLL files
+  # Copying the dynamically linked DLL files (Windows only)
+  ifeq ($(TARGET_WINDOWS),1)
 	$(shell a=$(PATH); b=$${a%%:*}; cp "$${b}/SDL2.dll" "$(BUILD_DIR)/SDL2.dll")
 
   ifeq ($(TARGET_32BIT),1)
 	  $(shell a=$(PATH); b=$${a%%:*}; cp "$${b}/libgcc_s_dw2-1.dll" "$(BUILD_DIR)/libgcc_s_dw2-1.dll")
 	  $(shell a=$(PATH); b=$${a%%:*}; cp "$${b}/libwinpthread-1.dll" "$(BUILD_DIR)/libwinpthread-1.dll")
   endif
+  endif
 endif
 
 .PHONY: all clean distclean default diff test load libultra

src/pc/gfx/gfx_pc.c

@@ -844,7 +844,12 @@ static void import_texture(int tile) {
 #ifdef TARGET_MACOS
     _NSGetExecutablePath(exec_path, &size);
 #else
-    readlink("/proc/self/exe", exec_path, size);
+    ssize_t len = readlink("/proc/self/exe", exec_path, size - 1);
+    if (len >= 0) {
+        exec_path[len] = '\0';
+    } else {
+        exec_path[0] = '\0';
+    }
 #endif
     dir = dirname(exec_path);
     const char gfx_path[1024];

tools/skyconv.c

@@ -230,29 +230,58 @@ void write_tiles() {
         exit(EXIT_FAILURE);
     }
 
-    strcat(buffer, "/");
+    size_t dirLength = strlen(buffer);
+    if (dirLength + 1 >= sizeof(buffer)) {
+        fprintf(stderr, "err: Image dir path too long\n");
+        exit(EXIT_FAILURE);
+    }
+
+    buffer[dirLength++] = '/';
+    buffer[dirLength] = '\0';
 
     switch(type) {
         case Skybox:
+            if (dirLength + strlen(skyboxName) >= sizeof(buffer)) {
+                fprintf(stderr, "err: Skybox name path too long\n");
+                exit(EXIT_FAILURE);
+            }
             strcat(buffer, skyboxName);
         break;
         case Cake:
+            if (dirLength + strlen("cake") >= sizeof(buffer)) {
+                fprintf(stderr, "err: Cake path too long\n");
+                exit(EXIT_FAILURE);
+            }
             strcat(buffer, "cake");
         break;
         case CakeEU:
+            if (dirLength + strlen("cake_eu") >= sizeof(buffer)) {
+                fprintf(stderr, "err: Cake path too long\n");
+                exit(EXIT_FAILURE);
+            }
             strcat(buffer, "cake_eu");
         break;
         default:
             exit(EXIT_FAILURE);
         break;
     }
 
-    int dirLength = strlen(buffer);
+    dirLength = strlen(buffer);
     char *filename = buffer + dirLength;
+    size_t remaining = sizeof(buffer) - dirLength;
+    if (remaining == 0) {
+        fprintf(stderr, "err: Image dir path too long\n");
+        exit(EXIT_FAILURE);
+    }
+
     for (int i = 0; i < props.numRows * props.numCols; i++) {
         if (!tiles[i].useless) {
             *filename = 0;
-            snprintf(filename, PATH_MAX, ".%d.rgba16.png", tiles[i].pos);
+            int written = snprintf(filename, remaining, ".%d.rgba16.png", tiles[i].pos);
+            if (written < 0 || (size_t) written >= remaining) {
+                fprintf(stderr, "err: Tile filename too long\n");
+                exit(EXIT_FAILURE);
+            }
             rgba2png(buffer, tiles[i].px, props.tileWidth, props.tileHeight);
         }
     }
@@ -676,4 +705,4 @@ int main(int argc, char *argv[]) {
 
 
     return EXIT_SUCCESS;
-}
+}