LXR linux/lib/Kconfig.kfence

   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