TYPO3 Core

A realy weird problem i can not track down...

In one application i use TYPO3 7 (7.4-dev at the moment [89139e81a49259ec03c5ea6b0c35734f9528f5f3])
First of all - i looked at the logs and there was no change regarding crop or permissions, so i think it still exists in master. I did not checkout the current master so far because i really lack time.

The situation is as follows:
A redactional user (sys_file_reference, crop, tt_content and all permissions set in the group) creates a new file reference. The reference points to a image - a very large one. Everything works fine so far. Then the new crop feature is used and suddenly the record can not be opened anymore (after saving). The error comes from PHP (memory limit - limit is at 512M)

BUT: When i open the record with an admin user - it works.
Even if i open it with a different backend user (with same group) - it works.

Only for one user it does not - neither if i simulate the user. So it has definitly to do with permissions.

The cropmask contained negative floatingpoint numbers - it was like: {"x":56.23968627450987,"y":-0.03011764705879614,"width":910.7576470588235,"height":683.0682352941177,"rotate":0}
Or {"x":-0.24181706943997588,"y":0,"width":6843.423065157541,"height":5132.567298868156,"rotate":0}

If the very large crop is the problem i think the imageprocessing order in the backend is wrong, only the ratio should be extracted and be applied on the size that is needed for the backend.