core: add VA overflow check in shdr_alloc_and_copy()
core: add VA overflow check in shdr_alloc_and_copy()

Make sure that no address overflow can occur when shdr_alloc_and_copy()
copies the signed header.

Signed-off-by: Jerome Forissier <ced78d268b4c9a0a20a59a9feeebd2ad90da03d3@linaro.org>
Reported-by: Bastien Simondi <fa964f737d98550ec78fc8da041b1f5763f7be04@netflix.com> [2.4]
Reviewed-by: Joakim Bech <741f90e2a7f4d9afbad8bd50be20560f4cf38962@linaro.org>

pascal-brand-st-dev/optee_os,pascal-brand-st-dev/optee_os,pascal-brand-st-dev/optee_os,pascal-brand-st-dev/optee_os,pascal-brand-st-dev/optee_os