Soil pipe through flat roof leak fix

[matlob]

Hi

I have a soil pipe that enters through a flat roof. Rain water is getting through the hole where the pipe enters and into the internal boxing in.

Is there a way to fix a collar on without removing any of the pipework or can I fix with blackjack paint or similarroof . The rainwater runs off past the pipe unfortunately. The roof is felt and gravel currently.

Thanks for any help or pointers to products I could use

 

[cross thread]

Bostick Flexacryl worked for me