1 # SPDX-License-Identifier: GPL-2.0-only
3 config HAVE_ARCH_KFENCE
7 bool "KFENCE: low-overhead sampling-based memory safety error detector"
8 depends on HAVE_ARCH_KFENCE && !KASAN && (SLAB || SLUB)
11 KFENCE is a low-overhead sampling-based detector of heap out-of-bounds
12 access, use-after-free, and invalid-free errors. KFENCE is designed
13 to have negligible cost to permit enabling it in production
16 Note that, KFENCE is not a substitute for explicit testing with tools
17 such as KASAN. KFENCE can detect a subset of bugs that KASAN can
18 detect, albeit at very different performance profiles. If you can
19 afford to use KASAN, continue using KASAN, for example in test
20 environments. If your kernel targets production use, and cannot
21 enable KASAN due to its cost, consider using KFENCE.
25 config KFENCE_STATIC_KEYS
26 bool "Use static keys to set up allocations"
28 depends on JUMP_LABEL # To ensure performance, require jump labels
30 Use static keys (static branches) to set up KFENCE allocations. Using
31 static keys is normally recommended, because it avoids a dynamic
32 branch in the allocator's fast path. However, with very low sample
33 intervals, or on systems that do not support jump labels, a dynamic
34 branch may still be an acceptable performance trade-off.
36 config KFENCE_SAMPLE_INTERVAL
37 int "Default sample interval in milliseconds"
40 The KFENCE sample interval determines the frequency with which heap
41 allocations will be guarded by KFENCE. May be overridden via boot
42 parameter "kfence.sample_interval".
44 Set this to 0 to disable KFENCE by default, in which case only
45 setting "kfence.sample_interval" to a non-zero value enables KFENCE.
47 config KFENCE_NUM_OBJECTS
48 int "Number of guarded objects available"
52 The number of guarded objects available. For each KFENCE object, 2
53 pages are required; with one containing the object and two adjacent
54 ones used as guard pages.
56 config KFENCE_STRESS_TEST_FAULTS
57 int "Stress testing of fault handling and error reporting" if EXPERT
60 The inverse probability with which to randomly protect KFENCE object
61 pages, resulting in spurious use-after-frees. The main purpose of
62 this option is to stress test KFENCE with concurrent error reports
63 and allocations/frees. A value of 0 disables stress testing logic.
65 Only for KFENCE testing; set to 0 if you are not a KFENCE developer.