kernel/security/Kconfig.hardening

1 # SPDX-License-Identifier: GPL-2.0-only
12 	  flaws, this plugin is available to identify and zero-initialize
23 	def_bool $(cc-option,-ftrivial-auto-var-init=pattern)
26 	def_bool $(cc-option,-ftrivial-auto-var-init=zero)
29 	# Clang 16 and later warn about using the -enable flag, but it
31 …def_bool $(cc-option,-ftrivial-auto-var-init=zero -enable-trivial-auto-var-init-zero-knowing-it-wi…
47 	  variables initialized), but the performance impact depends
64 		bool "zero-init structs marked for userspace (weak)"
68 		  Zero-initialize any structures on the stack containing
71 		  exposures, like CVE-2013-2141:
75 		bool "zero-init structs passed by reference (strong)"
80 		  Zero-initialize any structures on the stack that may
84 		  exposures, like CVE-2017-1000410:
87 		  As a side-effect, this keeps a lot of variables on the
93 		bool "zero-init everything passed by reference (very strong)"
98 		  Zero-initialize any stack variables that may be passed
104 		  As a side-effect, this keeps a lot of variables on the
110 		bool "pattern-init everything (strongest)"
121 		  non-NULL values, buffer sizes and indices are very big. The
122 		  pattern is situation-specific; Clang on 64-bit uses 0xAA
124 		  which use 0xFF repeating (-NaN). Clang on 32-bit uses 0xFF
128 		bool "zero-init everything (strongest and safest)"
138 		  (immediately NUL-terminated), pointers (NULL), indices
167 	  most uninitialized stack variable attacks, with the performance
171 	  The performance impact on a single CPU system kernel compilation
201 	  can be useful for estimating the STACKLEAK performance impact for
220 	  heap content exposures. The performance impact varies by
222 	  workloads have measured as high as 7%.
236 	  The performance impact varies by workload, but is more expensive
238 	  touching "cold" memory areas. Most cases see 3-5% impact. Some
239 	  synthetic workloads have measured as high as 8%.