Fix potential buffer overflows in USD export & OpenEXR

- Don't use the source string length +1 as the size of the destination
  (USD export & IMB_exr_get_handle_name).
- Correct undersized buffer being passed into imb_exr_insert_view_name.

source/blender/imbuf/intern/openexr/openexr_api.cpp

@@ -762,7 +762,7 @@ void *IMB_exr_get_handle_name(const char *name)
 
   if (data == nullptr) {
     data = (ExrHandle *)IMB_exr_get_handle();
-    BLI_strncpy(data->name, name, strlen(name) + 1);
+    STRNCPY(data->name, name);
   }
   return data;
 }
@@ -819,12 +819,16 @@ static void imb_exr_get_views(MultiPartInputFile &file, StringVector &views)
 }
 
 /* Multi-layer Blender files have the view name in all the passes (even the default view one). */
-static void imb_exr_insert_view_name(char *name_full, const char *passname, const char *viewname)
+static void imb_exr_insert_view_name(char name_full[EXR_TOT_MAXNAME + 1],
+                                     const char *passname,
+                                     const char *viewname)
 {
+  /* Match: `sizeof(ExrChannel::name)`. */
+  const size_t name_full_maxncpy = EXR_TOT_MAXNAME + 1;
   BLI_assert(!ELEM(name_full, passname, viewname));
 
   if (viewname == nullptr || viewname[0] == '\0') {
-    BLI_strncpy(name_full, passname, sizeof(ExrChannel::name));
+    BLI_strncpy(name_full, passname, name_full_maxncpy);
     return;
   }
 
@@ -836,10 +840,10 @@ static void imb_exr_insert_view_name(char *name_full, const char *passname, cons
   len = BLI_str_rpartition(passname, delims, &sep, &token);
 
   if (sep) {
-    BLI_snprintf(name_full, EXR_PASS_MAXNAME, "%.*s.%s.%s", int(len), passname, viewname, token);
+    BLI_snprintf(name_full, name_full_maxncpy, "%.*s.%s.%s", int(len), passname, viewname, token);
   }
   else {
-    BLI_snprintf(name_full, EXR_PASS_MAXNAME, "%s.%s", passname, viewname);
+    BLI_snprintf(name_full, name_full_maxncpy, "%s.%s", passname, viewname);
   }
 }
 
@@ -1140,7 +1144,7 @@ float *IMB_exr_channel_rect(void *handle,
 
   /* name has to be unique, thus it's a combination of layer, pass, view, and channel */
   if (layname && layname[0] != '\0') {
-    char temp_buf[EXR_PASS_MAXNAME];
+    char temp_buf[EXR_TOT_MAXNAME + 1];
     imb_exr_insert_view_name(temp_buf, name, viewname);
     STRNCPY(name, temp_buf);
   }

source/blender/io/usd/intern/usd_capi_export.cc

@@ -371,8 +371,8 @@ static void create_temp_path_for_usdz_export(const char *filepath,
   char usdc_temp_filepath[FILE_MAX];
   BLI_path_join(usdc_temp_filepath, FILE_MAX, BKE_tempdir_session(), "USDZ", usdc_file);
 
-  BLI_strncpy(job->unarchived_filepath, usdc_temp_filepath, strlen(usdc_temp_filepath) + 1);
-  BLI_strncpy(job->usdz_filepath, filepath, strlen(filepath) + 1);
+  STRNCPY(job->unarchived_filepath, usdc_temp_filepath);
+  STRNCPY(job->usdz_filepath, filepath);
 
   MEM_freeN(usdc_file);
 }