Both issues reported in QTBUG-120396 came from the same dubious piece of code, which predates the public Qt history if (path->size() >= 2 && in[0].unicode() == '.' && in[1].unicode() == '/') in += 2; else if (path->size() >= 3 && in[0].unicode() == '.' && in[1].unicode() == '.' && in[2].unicode() == '/') in += 3; It makes no sense to check path->size() inside the loop, as the in pointer will have advanced past the beginning and the remaining size of the input will not be path->size(). It additionally had theoretical UB in expressions like in <= end - 4 for paths that were less than 4 characters long (it cannot happen with current QString because of the QArrayData header before the payload). So this commit rewrites the function to fix those issues and some others found during the unit-testing. It gives the function a major simplification. Fixes: QTBUG-120396 Pick-to: 6.5 6.8 Change-Id: I46feca3a447244a8ba19fffd17e012c27e410056 Reviewed-by: Edward Welbourne <edward.welbourne@qt.io> Reviewed-by: Ahmad Samir <a.samirh78@gmail.com>