1# SPDX-License-Identifier: GPL-2.0-only 2 3config HAVE_ARCH_KFENCE 4 bool 5 6menuconfig KFENCE 7 bool "KFENCE: low-overhead sampling-based memory safety error detector" 8 depends on HAVE_ARCH_KFENCE && (SLAB || SLUB) 9 select STACKTRACE 10 select IRQ_WORK 11 help 12 KFENCE is a low-overhead sampling-based detector of heap out-of-bounds 13 access, use-after-free, and invalid-free errors. KFENCE is designed 14 to have negligible cost to permit enabling it in production 15 environments. 16 17 See <file:Documentation/dev-tools/kfence.rst> for more details. 18 19 Note that, KFENCE is not a substitute for explicit testing with tools 20 such as KASAN. KFENCE can detect a subset of bugs that KASAN can 21 detect, albeit at very different performance profiles. If you can 22 afford to use KASAN, continue using KASAN, for example in test 23 environments. If your kernel targets production use, and cannot 24 enable KASAN due to its cost, consider using KFENCE. 25 26if KFENCE 27 28config KFENCE_STATIC_KEYS 29 bool "Use static keys to set up allocations" 30 default y 31 depends on JUMP_LABEL # To ensure performance, require jump labels 32 help 33 Use static keys (static branches) to set up KFENCE allocations. Using 34 static keys is normally recommended, because it avoids a dynamic 35 branch in the allocator's fast path. However, with very low sample 36 intervals, or on systems that do not support jump labels, a dynamic 37 branch may still be an acceptable performance trade-off. 38 39config KFENCE_SAMPLE_INTERVAL 40 int "Default sample interval in milliseconds" 41 default 100 42 help 43 The KFENCE sample interval determines the frequency with which heap 44 allocations will be guarded by KFENCE. May be overridden via boot 45 parameter "kfence.sample_interval". 46 47 Set this to 0 to disable KFENCE by default, in which case only 48 setting "kfence.sample_interval" to a non-zero value enables KFENCE. 49 50config KFENCE_NUM_OBJECTS 51 int "Number of guarded objects available" 52 range 1 65535 53 default 255 54 help 55 The number of guarded objects available. For each KFENCE object, 2 56 pages are required; with one containing the object and two adjacent 57 ones used as guard pages. 58 59config KFENCE_STRESS_TEST_FAULTS 60 int "Stress testing of fault handling and error reporting" if EXPERT 61 default 0 62 help 63 The inverse probability with which to randomly protect KFENCE object 64 pages, resulting in spurious use-after-frees. The main purpose of 65 this option is to stress test KFENCE with concurrent error reports 66 and allocations/frees. A value of 0 disables stress testing logic. 67 68 Only for KFENCE testing; set to 0 if you are not a KFENCE developer. 69 70config KFENCE_KUNIT_TEST 71 tristate "KFENCE integration test suite" if !KUNIT_ALL_TESTS 72 default KUNIT_ALL_TESTS 73 depends on TRACEPOINTS && KUNIT 74 help 75 Test suite for KFENCE, testing various error detection scenarios with 76 various allocation types, and checking that reports are correctly 77 output to console. 78 79 Say Y here if you want the test to be built into the kernel and run 80 during boot; say M if you want the test to build as a module; say N 81 if you are unsure. 82 83endif # KFENCE 84