Lines Matching +full:1 +full:- +full:based
5 --------
8 designed to find out-of-bounds and use-after-free bugs.
12 1. Generic KASAN
13 2. Software Tag-Based KASAN
14 3. Hardware Tag-Based KASAN
20 Software Tag-Based KASAN or SW_TAGS KASAN, enabled with CONFIG_KASAN_SW_TAGS,
23 using it for testing on memory-restricted devices with real workloads.
25 Hardware Tag-Based KASAN or HW_TAGS KASAN, enabled with CONFIG_KASAN_HW_TAGS,
26 is the mode intended to be used as an in-field memory bug detector or as a
34 The Generic and the Software Tag-Based modes are commonly referred to as the
35 software modes. The Software Tag-Based and the Hardware Tag-Based modes are
36 referred to as the tag-based modes.
39 -------
45 xtensa, and the tag-based KASAN modes are supported only on arm64.
50 Software KASAN modes use compile-time instrumentation to insert validity checks
52 support for that. The Hardware Tag-Based mode relies on hardware to perform
59 Software Tag-Based KASAN requires GCC 11+
62 Hardware Tag-Based KASAN requires GCC 10+ or Clang 12+.
70 Software Tag-Based KASAN supports slab, page_alloc, vmalloc, and stack memory.
72 Hardware Tag-Based KASAN supports slab, page_alloc, and non-executable vmalloc
76 Hardware Tag-Based KASAN only supports SLUB.
79 -----
86 ``CONFIG_KASAN_SW_TAGS`` (to enable Software Tag-Based KASAN), and
87 ``CONFIG_KASAN_HW_TAGS`` (to enable Hardware Tag-Based KASAN).
110 - ``kasan.fault=report`` or ``=panic`` controls whether to only print a KASAN
114 Software and Hardware Tag-Based KASAN modes (see the section about various
117 - ``kasan.stacktrace=off`` or ``=on`` disables or enables alloc and free stack
119 - ``kasan.stack_ring_size=<number of entries>`` specifies the number of entries
122 Hardware Tag-Based KASAN mode is intended for use in production as a security
126 - ``kasan=off`` or ``=on`` controls whether KASAN is enabled (default: ``on``).
128 - ``kasan.mode=sync``, ``=async`` or ``=asymm`` controls whether KASAN
140 - ``kasan.vmalloc=off`` or ``=on`` disables or enables tagging of vmalloc
149 BUG: KASAN: slab-out-of-bounds in kmalloc_oob_right+0xa8/0xbc [test_kasan]
150 Write of size 1 at addr ffff8801f44ec37b by task insmod/2760
152 CPU: 1 PID: 2760 Comm: insmod Not tainted 4.19.0-rc3+ #698
153 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1 04/01/2014
200 which belongs to the cache kmalloc-128 of size 128
202 128-byte region [ffff8801f44ec300, ffff8801f44ec380)
204 page:ffffea0007d13b00 count:1 mapcount:0 mapping:ffff8801f7001640 index:0x0
222 and a stack trace of where the object was freed (in case of a use-after-free
236 memory region are accessible; number N (1 <= N <= 7) means that the first N
237 bytes are accessible, and other (8 - N) bytes are not; any negative value
238 indicates that the entire 8-byte word is inaccessible. KASAN uses different
245 For tag-based KASAN modes, this last report section shows the memory tags around
248 Note that KASAN bug titles (like ``slab-out-of-bounds`` or ``use-after-free``)
249 are best-effort: KASAN prints the most probable bug type based on the limited
258 ----------------------
264 safe to access and use compile-time instrumentation to insert shadow memory
267 Generic KASAN dedicates 1/8th of kernel memory to its shadow memory (16TB
282 Compile-time instrumentation is used to insert memory access checks. Compiler
284 each memory access of size 1, 2, 4, 8, or 16. These functions check whether
289 enlarges the kernel, but it gives an x1.1-x2 performance boost over the
290 outline-instrumented kernel.
295 Software Tag-Based KASAN
298 Software Tag-Based KASAN uses a software memory tagging approach to checking
301 Software Tag-Based KASAN uses the Top Byte Ignore (TBI) feature of arm64 CPUs
303 to store memory tags associated with each 16-byte memory cell (therefore, it
304 dedicates 1/16th of the kernel memory for shadow memory).
306 On each memory allocation, Software Tag-Based KASAN generates a random tag, tags
310 Software Tag-Based KASAN uses compile-time instrumentation to insert checks
313 this memory. In case of a tag mismatch, Software Tag-Based KASAN prints a bug
316 Software Tag-Based KASAN also has two instrumentation modes (outline, which
323 Software Tag-Based KASAN uses 0xFF as a match-all pointer tag (accesses through
327 Hardware Tag-Based KASAN
330 Hardware Tag-Based KASAN is similar to the software mode in concept but uses
334 Hardware Tag-Based KASAN is currently only implemented for arm64 architecture
335 and based on both arm64 Memory Tagging Extension (MTE) introduced in ARMv8.5
344 Hardware Tag-Based KASAN uses 0xFF as a match-all pointer tag (accesses through
348 If the hardware does not support MTE (pre ARMv8.5), Hardware Tag-Based KASAN
351 Note that enabling CONFIG_KASAN_HW_TAGS always results in in-kernel TBI being
355 Hardware Tag-Based KASAN only reports the first found bug. After that, MTE tag
359 -------------
374 other areas - such as vmalloc and vmemmap space - a single read-only
375 page is mapped over the shadow area. This read-only shadow page
384 lives in vmalloc space, it will be shadowed by the read-only page, and
415 This will require changes in arch-specific code.
421 --------------
438 - For a single file (e.g., main.o)::
442 - For all files in one directory::
446 For software KASAN modes, to disable instrumentation on a per-function basis,
447 use the KASAN-specific ``__no_sanitize_address`` function attribute or the
450 Note that disabling compiler instrumentation (either on a per-file or a
451 per-function basis) makes KASAN ignore the accesses that happen directly in
454 Tag-Based KASAN, which does not use compiler instrumentation.
461 For tag-based KASAN modes, to disable access checking, use
464 restoring the per-page KASAN tag via ``page_kasan_tag``/``page_kasan_tag_set``.
472 1. Tests that are integrated with the KUnit Test Framework. Enabled with
481 Each KUnit-compatible KASAN test prints one of multiple KASAN reports if an
486 ok 28 - kmalloc_double_kzfree
492 not ok 4 - kmalloc_large_oob_right
498 not ok 44 - kmalloc_double_kzfree
503 ok 1 - kasan
507 not ok 1 - kasan
509 There are a few ways to run KUnit-compatible KASAN tests.
511 1. Loadable module
513 With ``CONFIG_KUNIT`` enabled, KASAN-KUnit tests can be built as a loadable
516 2. Built-In
518 With ``CONFIG_KUNIT`` built-in, KASAN-KUnit tests can be built-in as well.
519 In this case, the tests will run at boot as a late-init call.
523 With ``CONFIG_KUNIT`` and ``CONFIG_KASAN_KUNIT_TEST`` built-in, it is also
526 See `KUnit documentation <https://www.kernel.org/doc/html/latest/dev-tools/kunit/index.html>`_
527 for more up-to-date information on ``kunit_tool``.
529 .. _KUnit: https://www.kernel.org/doc/html/latest/dev-tools/kunit/index.html