STM32F4 executable stack?
The stm32 can happily execute from RAM, so yes, this is possible. Depending on which variant of STM32F4 you have different sections of SRAM are attached to the I-bus, this is detailed in the reference manual for your part.

Why do you want to do this? What problem are you trying to solve?

If you are trying to execute code from RAM there are well defined ways to achieve this with the linker.