SafeSEH and x64

Question

I read here that

/SAFESEH is only valid when linking for x86 targets. /SAFESEH is not supported for platforms that already have the exception handlers noted. For example, on x64 and Itanium, all exception handlers are noted in the PDATA.

What does this mean? Is the SEH chain checked with a x64 target (stored into the PDATA structure) ? Or there is no safeSEH check with x64 targets?

Answer 1

SafeSEH is a mechanism that protects stack-based exception handler chains from being overwritten. However, on x64 and Itanium architectures, the exception handlers are table-based (i.e. stored in PDATA) and therefore cannot be overwritten directly by a stack buffer overflow - they're simply not on the stack. As such, SafeSEH is irrelevant to those systems.