6: kd> u fffff801`7bfcc010
nt!_security_check_cookie:
fffff801`7bfcc010 483b0d49628400 cmp rcx,qword ptr [nt!_security_cookie (fffff801`7c812260)] << Compare the generated cookie and the one present on the stack
fffff801`7bfcc017 7510 jne nt!_security_check_cookie+0x19 (fffff801`7bfcc029)
fffff801`7bfcc019 48c1c110 rol rcx,10h
fffff801`7bfcc01d 66f7c1ffff test cx,0FFFFh << Check the high 16-bits; remember the h postfix means hexadecimal format, so it's comparing the 16-bits of the rcx register to 0xFFFF
fffff801`7bfcc022 7501 jne nt!_security_check_cookie+0x15 (fffff801`7bfcc025) << Validate the security cookie, and then fail
fffff801`7bfcc024 c3 ret
fffff801`7bfcc025 48c1c910 ror rcx,10h
fffff801`7bfcc029 e9824c0e00 jmp nt!_report_gsfailure (fffff801`7c0b0cb0)