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Alexander Potapenko 1eee152fce
BACKPORT: mm: add Kernel Electric-Fence infrastructure
Patch series "KFENCE: A low-overhead sampling-based memory safety error detector", v7.

This adds the Kernel Electric-Fence (KFENCE) infrastructure. KFENCE is a
low-overhead sampling-based memory safety error detector of heap
use-after-free, invalid-free, and out-of-bounds access errors.  This
series enables KFENCE for the x86 and arm64 architectures, and adds
KFENCE hooks to the SLAB and SLUB allocators.

KFENCE is designed to be enabled in production kernels, and has near
zero performance overhead. Compared to KASAN, KFENCE trades performance
for precision. The main motivation behind KFENCE's design, is that with
enough total uptime KFENCE will detect bugs in code paths not typically
exercised by non-production test workloads. One way to quickly achieve a
large enough total uptime is when the tool is deployed across a large
fleet of machines.

KFENCE objects each reside on a dedicated page, at either the left or
right page boundaries. The pages to the left and right of the object
page are "guard pages", whose attributes are changed to a protected
state, and cause page faults on any attempted access to them. Such page
faults are then intercepted by KFENCE, which handles the fault
gracefully by reporting a memory access error.

Guarded allocations are set up based on a sample interval (can be set
via kfence.sample_interval). After expiration of the sample interval,
the next allocation through the main allocator (SLAB or SLUB) returns a
guarded allocation from the KFENCE object pool. At this point, the timer
is reset, and the next allocation is set up after the expiration of the
interval.

To enable/disable a KFENCE allocation through the main allocator's
fast-path without overhead, KFENCE relies on static branches via the
static keys infrastructure. The static branch is toggled to redirect the
allocation to KFENCE.

The KFENCE memory pool is of fixed size, and if the pool is exhausted no
further KFENCE allocations occur. The default config is conservative
with only 255 objects, resulting in a pool size of 2 MiB (with 4 KiB
pages).

We have verified by running synthetic benchmarks (sysbench I/O,
hackbench) and production server-workload benchmarks that a kernel with
KFENCE (using sample intervals 100-500ms) is performance-neutral
compared to a non-KFENCE baseline kernel.

KFENCE is inspired by GWP-ASan [1], a userspace tool with similar
properties. The name "KFENCE" is a homage to the Electric Fence Malloc
Debugger [2].

For more details, see Documentation/dev-tools/kfence.rst added in the
series -- also viewable here:

	https://raw.githubusercontent.com/google/kasan/kfence/Documentation/dev-tools/kfence.rst

[1] http://llvm.org/docs/GwpAsan.html
[2] https://linux.die.net/man/3/efence

This patch (of 9):

This adds the Kernel Electric-Fence (KFENCE) infrastructure. KFENCE is a
low-overhead sampling-based memory safety error detector of heap
use-after-free, invalid-free, and out-of-bounds access errors.

KFENCE is designed to be enabled in production kernels, and has near
zero performance overhead. Compared to KASAN, KFENCE trades performance
for precision. The main motivation behind KFENCE's design, is that with
enough total uptime KFENCE will detect bugs in code paths not typically
exercised by non-production test workloads. One way to quickly achieve a
large enough total uptime is when the tool is deployed across a large
fleet of machines.

KFENCE objects each reside on a dedicated page, at either the left or
right page boundaries. The pages to the left and right of the object
page are "guard pages", whose attributes are changed to a protected
state, and cause page faults on any attempted access to them. Such page
faults are then intercepted by KFENCE, which handles the fault
gracefully by reporting a memory access error. To detect out-of-bounds
writes to memory within the object's page itself, KFENCE also uses
pattern-based redzones. The following figure illustrates the page
layout:

  ---+-----------+-----------+-----------+-----------+-----------+---
     | xxxxxxxxx | O :       | xxxxxxxxx |       : O | xxxxxxxxx |
     | xxxxxxxxx | B :       | xxxxxxxxx |       : B | xxxxxxxxx |
     | x GUARD x | J : RED-  | x GUARD x | RED-  : J | x GUARD x |
     | xxxxxxxxx | E :  ZONE | xxxxxxxxx |  ZONE : E | xxxxxxxxx |
     | xxxxxxxxx | C :       | xxxxxxxxx |       : C | xxxxxxxxx |
     | xxxxxxxxx | T :       | xxxxxxxxx |       : T | xxxxxxxxx |
  ---+-----------+-----------+-----------+-----------+-----------+---

Guarded allocations are set up based on a sample interval (can be set
via kfence.sample_interval). After expiration of the sample interval, a
guarded allocation from the KFENCE object pool is returned to the main
allocator (SLAB or SLUB). At this point, the timer is reset, and the
next allocation is set up after the expiration of the interval.

To enable/disable a KFENCE allocation through the main allocator's
fast-path without overhead, KFENCE relies on static branches via the
static keys infrastructure. The static branch is toggled to redirect the
allocation to KFENCE. To date, we have verified by running synthetic
benchmarks (sysbench I/O, hackbench) that a kernel compiled with KFENCE
is performance-neutral compared to the non-KFENCE baseline.

For more details, see Documentation/dev-tools/kfence.rst (added later in
the series).

Link: https://lkml.kernel.org/r/20201103175841.3495947-2-elver@google.com
Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Alexander Potapenko <glider@google.com>
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
Reviewed-by: SeongJae Park <sjpark@amazon.de>
Co-developed-by: Marco Elver <elver@google.com>
Reviewed-by: Jann Horn <jannh@google.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Paul E. McKenney <paulmck@kernel.org>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christopher Lameter <cl@linux.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Hillf Danton <hdanton@sina.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Joern Engel <joern@purestorage.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Bug: 177201466
(cherry picked from commit 2a8dede73c3496bbd917644657f3735a4f508cb9
    https://github.com/hnaz/linux-mm v5.11-rc4-mmots-2021-01-21-20-10)
[glider: dropped KCSAN bits missing in 5.4,
         resolved minor conflict in init/main.c]
Test: CONFIG_KFENCE_KUNIT_TEST=y passes on Cuttlefish
Signed-off-by: Alexander Potapenko <glider@google.com>
Change-Id: I6b474675cc9732c31118df53fa06c3997f577218
2026-05-07 17:24:01 +03:00
android Merge android11-5.4.302(91d385eb) into msm-5.4 2026-01-30 11:41:11 +05:30
arch UPSTREAM: net: retrieve netns cookie via getsocketopt 2026-05-07 10:18:28 -04:00
block Merge android11-5.4.302(91d385eb) into msm-5.4 2026-01-30 11:41:11 +05:30
certs
crypto BACKPORT: crypto: lib/sha1 - rename "sha" to "sha1" 2025-12-23 13:36:17 -08:00
Documentation UPSTREAM: BACKPORT: procfs/dmabuf: add inode number to /proc/*/fdinfo 2026-05-07 10:19:25 -04:00
drivers devfreq: bimc-bwmon: Don't free/reallocate IRQ during suspend/resume 2026-05-07 14:20:06 +00:00
fs FROMGIT: procfs: prevent unpriveleged processes accessing fdinfo dir 2026-05-07 10:19:32 -04:00
include BACKPORT: mm: add Kernel Electric-Fence infrastructure 2026-05-07 17:24:01 +03:00
init BACKPORT: mm: add Kernel Electric-Fence infrastructure 2026-05-07 17:24:01 +03:00
ipc ipc: adjust proc_ipc_sem_dointvec definition to match prototype 2026-02-01 20:37:47 -08:00
kernel Revert "UPSTREAM: seccomp: Remove bogus __user annotations" 2026-05-07 10:17:18 -04:00
lib BACKPORT: mm: add Kernel Electric-Fence infrastructure 2026-05-07 17:24:01 +03:00
LICENSES
mm BACKPORT: mm: add Kernel Electric-Fence infrastructure 2026-05-07 17:24:01 +03:00
net BACKPORT: net: core: enable SO_BINDTODEVICE for non-root users 2026-05-07 10:18:47 -04:00
samples UPSTREAM: devmap: Adjust tracepoint for map-less queue flush 2025-12-23 13:35:54 -08:00
scripts BACKPORT: kbuild: Switch to 'f' variants of integrated assembler flag 2026-05-05 20:02:23 +03:00
security BACKPORT: bpf: Add lockdown check for probe_write_user helper 2026-02-01 20:44:42 -08:00
sound Merge android11-5.4.302(91d385eb) into msm-5.4 2026-01-30 11:41:11 +05:30
techpack Merge tag 'LA.UM.9.14.1.r1-21100-QCM6490.QISI15.0' of https://git.codelinaro.org/clo/la/platform/vendor/opensource/video-driver into android13-5.4-lahaina 2026-04-30 21:20:07 +03:00
tools UPSTREAM: selftests/seccomp: Compare bitmap vs filter overhead 2026-05-07 10:17:18 -04:00
usr Merge android11-5.4.302(91d385eb) into msm-5.4 2026-01-30 11:41:11 +05:30
virt KVM: arm64: Ignore PMCNTENSET_EL0 while checking for overflow status 2024-12-19 18:05:04 +01:00
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore Merge tag 'ASB-2024-12-05_11-5.4' of https://android.googlesource.com/kernel/common into android13-5.4-lahaina 2024-12-17 03:24:53 +02:00
.mailmap
Android.mk
Androidbp
build.config.aarch64
build.config.allmodconfig
build.config.allmodconfig.aarch64
build.config.allmodconfig.arm
build.config.allmodconfig.x86_64
build.config.arm
build.config.common
build.config.db845c ANDROID: db845c: Enable device tree overlay support 2024-01-13 10:38:25 +05:30
build.config.gki
build.config.gki-debug.aarch64
build.config.gki-debug.x86_64
build.config.gki.aarch64 ANDROID: GKI: add Trimble symbol list 2025-01-16 06:41:15 -08:00
build.config.gki.x86_64
build.config.gki_kasan
build.config.gki_kasan.aarch64
build.config.gki_kasan.x86_64
build.config.gki_kprobes
build.config.gki_kprobes.aarch64
build.config.gki_kprobes.x86_64
build.config.hikey960
build.config.msm.common
build.config.msm.gki
build.config.msm.lahaina
build.config.x86_64
build.targets
COPYING
CREDITS
gen_headers_arm.bp Merge android11-5.4.249+ (d57e792) into msm-5.4 2023-09-28 16:45:28 +05:30
gen_headers_arm64.bp Merge android11-5.4.249+ (d57e792) into msm-5.4 2023-09-28 16:45:28 +05:30
gen_headers_arm64_auto.bp
gen_headers_arm_auto.bp
Kbuild
Kconfig
kernel_headers.py
LICENSE
MAINTAINERS UPSTREAM: bpf: Add sockmap hooks for UDP sockets 2026-02-01 20:39:38 -08:00
Makefile BACKPORT: kbuild: check CONFIG_AS_IS_LLVM instead of LLVM_IAS 2026-05-05 20:02:23 +03:00
modules.list.msm.lahaina
OWNERS ANDROID: Use GKI Dr. No OWNERS file 2023-12-04 13:28:17 +00:00
README
README.md

How do I submit patches to Android Common Kernels

  1. BEST: Make all of your changes to upstream Linux. If appropriate, backport to the stable releases. These patches will be merged automatically in the corresponding common kernels. If the patch is already in upstream Linux, post a backport of the patch that conforms to the patch requirements below.

  2. LESS GOOD: Develop your patches out-of-tree (from an upstream Linux point-of-view). Unless these are fixing an Android-specific bug, these are very unlikely to be accepted unless they have been coordinated with kernel-team@android.com. If you want to proceed, post a patch that conforms to the patch requirements below.

Common Kernel patch requirements

  • All patches must conform to the Linux kernel coding standards and pass script/checkpatch.pl
  • Patches shall not break gki_defconfig or allmodconfig builds for arm, arm64, x86, x86_64 architectures (see https://source.android.com/setup/build/building-kernels)
  • If the patch is not merged from an upstream branch, the subject must be tagged with the type of patch: UPSTREAM:, BACKPORT:, FROMGIT:, FROMLIST:, or ANDROID:.
  • All patches must have a Change-Id: tag (see https://gerrit-review.googlesource.com/Documentation/user-changeid.html)
  • If an Android bug has been assigned, there must be a Bug: tag.
  • All patches must have a Signed-off-by: tag by the author and the submitter

Additional requirements are listed below based on patch type

Requirements for backports from mainline Linux: UPSTREAM:, BACKPORT:

  • If the patch is a cherry-pick from Linux mainline with no changes at all
    • tag the patch subject with UPSTREAM:.
    • add upstream commit information with a (cherry-picked from ...) line
    • Example:
      • if the upstream commit message is
        important patch from upstream

        This is the detailed description of the important patch

        Signed-off-by: Fred Jones <fred.jones@foo.org>
    - then Joe Smith would upload the patch for the common kernel as
        UPSTREAM: important patch from upstream

        This is the detailed description of the important patch

        Signed-off-by: Fred Jones <fred.jones@foo.org>

        Bug: 135791357
        Change-Id: I4caaaa566ea080fa148c5e768bb1a0b6f7201c01
        (cherry-picked from c31e73121f4c1ec41143423ac6ce3ce6dafdcec1)
        Signed-off-by: Joe Smith <joe.smith@foo.org>
  • If the patch requires any changes from the upstream version, tag the patch with BACKPORT: instead of UPSTREAM:.
    • use the same tags as UPSTREAM:
    • add comments about the changes under the (cherry-picked from ...) line
    • Example:
        BACKPORT: important patch from upstream

        This is the detailed description of the important patch

        Signed-off-by: Fred Jones <fred.jones@foo.org>

        Bug: 135791357
        Change-Id: I4caaaa566ea080fa148c5e768bb1a0b6f7201c01
        (cherry-picked from c31e73121f4c1ec41143423ac6ce3ce6dafdcec1)
        [ Resolved minor conflict in drivers/foo/bar.c ]
        Signed-off-by: Joe Smith <joe.smith@foo.org>

Requirements for other backports: FROMGIT:, FROMLIST:,

  • If the patch has been merged into an upstream maintainer tree, but has not yet been merged into Linux mainline
    • tag the patch subject with FROMGIT:
    • add info on where the patch came from as (cherry picked from commit <sha1> <repo> <branch>). This must be a stable maintainer branch (not rebased, so don't use linux-next for example).
    • if changes were required, use BACKPORT: FROMGIT:
    • Example:
      • if the commit message in the maintainer tree is
        important patch from upstream

        This is the detailed description of the important patch

        Signed-off-by: Fred Jones <fred.jones@foo.org>
    - then Joe Smith would upload the patch for the common kernel as
        FROMGIT: important patch from upstream

        This is the detailed description of the important patch

        Signed-off-by: Fred Jones <fred.jones@foo.org>

        Bug: 135791357
        (cherry picked from commit 878a2fd9de10b03d11d2f622250285c7e63deace
         https://git.kernel.org/pub/scm/linux/kernel/git/foo/bar.git test-branch)
        Change-Id: I4caaaa566ea080fa148c5e768bb1a0b6f7201c01
        Signed-off-by: Joe Smith <joe.smith@foo.org>
  • If the patch has been submitted to LKML, but not accepted into any maintainer tree
    • tag the patch subject with FROMLIST:
    • add a Link: tag with a link to the submittal on lore.kernel.org
    • if changes were required, use BACKPORT: FROMLIST:
    • Example:
        FROMLIST: important patch from upstream

        This is the detailed description of the important patch

        Signed-off-by: Fred Jones <fred.jones@foo.org>

        Bug: 135791357
        Link: https://lore.kernel.org/lkml/20190619171517.GA17557@someone.com/
        Change-Id: I4caaaa566ea080fa148c5e768bb1a0b6f7201c01
        Signed-off-by: Joe Smith <joe.smith@foo.org>

Requirements for Android-specific patches: ANDROID:

  • If the patch is fixing a bug to Android-specific code
    • tag the patch subject with ANDROID:
    • add a Fixes: tag that cites the patch with the bug
    • Example:
        ANDROID: fix android-specific bug in foobar.c

        This is the detailed description of the important fix

        Fixes: 1234abcd2468 ("foobar: add cool feature")
        Change-Id: I4caaaa566ea080fa148c5e768bb1a0b6f7201c01
        Signed-off-by: Joe Smith <joe.smith@foo.org>
  • If the patch is a new feature
    • tag the patch subject with ANDROID:
    • add a Bug: tag with the Android bug (required for android-specific features)

Vibrator driver for HHG device

How to merge the driver into kernel source tree

  1. Copy ${this_project}/drivers/hid/hid-aksys.c into ${your_kernel_root}/drivers/hid/

  2. Compare and merge ${this_project}/drivers/hid/hid-ids.h into ${your_kernel_root}/drivers/hid/hid-ids.h : Add the following code before the last line of this file

    	#define USB_VENDER_ID_QUALCOMM  0x0a12
    	#define USB_VENDER_ID_TEMP_HHG_AKSY 0x1234
    	#define USB_PRODUCT_ID_AKSYS_HHG  0x1000
    
  3. Merge ${this_project}/drivers/hid/Kconfig into ${your_kernel_root}/drivers/hid/Kconfig : Add the following code before the last line of this file

    config HID_AKSYS_QRD
    	tristate "AKSys gamepad USB adapter support"
    	depends on HID
    	---help---
    	Support for AKSys gamepad USB adapter
    
    config AKSYS_QRD_FF
    	bool "AKSys gamepad USB adapter force feedback support"
    	depends on HID_AKSYS_QRD
    	select INPUT_FF_MEMLESS
    	---help---
    	Say Y here if you have a AKSys gamepad USB adapter and want to
    	enable force feedback support for it.
    
  4. Merge ${this_project}/drivers/hid/Makefile into ${your_kernel_root}/drivers/hid/Makefile : Add the following code at the end of this file

    obj-$(CONFIG_HID_AKSYS_QRD)	+= hid-aksys.o
    
  5. Modify your kernel's default build configuration file. Add the following two lines:

    CONFIG_HID_AKSYS_QRD=m
    CONFIG_AKSYS_QRD_FF=y