Fix parsing of long latin strings in the json parser

Latin1 strings are usually stored as 8 bit data in the json binary
format. But that data structure has a size limitation of 16bit, so
we need to fall back to storing the string as 16 bit data if it is
too long.

Task-number: QTBUG-30946
Change-Id: I0069b1367030b0b2f819fd1f04e34c9e2534a2a3
Reviewed-by: Jędrzej Nowacki <jedrzej.nowacki@digia.com>

1 files changed, 2 insertions, 1 deletions

diff --git a/src/corelib/json/qjsonparser.cpp b/src/corelib/json/qjsonparser.cpp
index 7989d18901..b151af7955 100644
--- a/src/corelib/json/qjsonparser.cpp
+++ b/src/corelib/json/qjsonparser.cpp
@@ -886,7 +886,8 @@ bool Parser::parseString(bool *latin1)
                 return false;
             }
         }
-        if (ch > 0xff) {
+        // bail out if the string is not pure latin1 or too long to hold as a latin1string (which has only 16 bit for the length)
+        if (ch > 0xff || json - start >= 0x8000) {
             *latin1 = false;
             break;
         }