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# Copyright 2020 syzkaller project authors. All rights reserved.
# Use of this source code is governed by Apache 2 LICENSE that can be found in the LICENSE file.
# Common config fragments required by syzbot for all kernels
# CONFIG_DEBUG_MEMORY was once added to mm tree and cause disabling of KASAN,
# which in turn caused storm of assorted crashes after silent memory corruptions.
# The config was reverted, but we keep it here for the case it is reintroduced to kernel again.
# CONFIG_TWIST_KERNEL_BEHAVIOR can be used to prevent fuzzers from trying stupid things.
# See https://github.com/google/syzkaller/issues/1622 for details.
# DEBUG_AID_FOR_SYZBOT can be used to enable any additional temporal debugging features in linux-next tree.
# It is kept in verbatim because it has for some reason disappeared from next-20220222.
# CONFIG_RCU_EXP_CPU_STALL_TIMEOUT is now only in the linux-next branch.
# By default it is set to a too small value, which causes tons of `rcu_preempt detected expedited stalls
# on CPUs/tasks`.
# TODO: turn it into a normal config once it reaches mainline.
verbatim: |
CONFIG_DEBUG_MEMORY=y
CONFIG_TWIST_KERNEL_BEHAVIOR=y
CONFIG_TWIST_FOR_SYZKALLER_TESTING=y
CONFIG_DEBUG_AID_FOR_SYZBOT=y
CONFIG_RCU_EXP_CPU_STALL_TIMEOUT=21000
config:
# Required to enable some other configs we set.
- EXPERT
- DEBUG_KERNEL
# Continuous fuzzing is more important than breaking on warnings.
- WERROR: n
# panic=86400: prevents kernel from rebooting so that we don't get reboot output in all crash reports.
# Huge page overcommit is disabled by default, allowing some overcommit
# with vm.nr_overcommit_hugepages is intended to give more coverage.
# secretmem_enable enables memfd_secret syscall.
- CMDLINE: "earlyprintk=serial net.ifnames=0 sysctl.kernel.hung_task_all_cpu_backtrace=1 ima_policy=tcb nf-conntrack-ftp.ports=20000 nf-conntrack-tftp.ports=20000 nf-conntrack-sip.ports=20000 nf-conntrack-irc.ports=20000 nf-conntrack-sane.ports=20000 binder.debug_mask=0 rcupdate.rcu_expedited=1 no_hash_pointers page_owner=on sysctl.vm.nr_hugepages=4 sysctl.vm.nr_overcommit_hugepages=4 secretmem.enable=1 sysctl.max_rcu_stall_to_panic=1 msr.allow_writes=off"
# We don't need lots, but some configs set it to 2 which is too low.
- NR_CPUS: 8
# We slowdown execution significantly and there is no point in low latency under test.
- HZ_100
- RCU_TRACE: n
# KPROBES pollute coverage and needlessly slow down execution.
- KPROBES: n
# Slows down execution and sometimes fuzzer actually enables it.
- STACK_TRACER: n
- FUNCTION_TRACER: n
# Slows down execution.
- RETPOLINE: n
- PAGE_TABLE_ISOLATION: n
- LATENCYTOP: n
- SCHED_DEBUG: n
# Speeds up randomness initialization.
- HW_RANDOM
- HW_RANDOM_VIRTIO
- HW_RANDOM_INTEL: n
- HW_RANDOM_AMD: n
- HW_RANDOM_VIA: n
- RANDOM_TRUST_CPU: [-arm, -riscv]
- RANDOM_TRUST_BOOTLOADER: [v4.16]
# For detection of supported syscalls
- KALLSYMS
- KALLSYMS_ALL
- KALLSYMS_BASE_RELATIVE
# For namespace sandbox.
- NAMESPACES
- USER_NS
- UTS_NS
# Depends on CONFIG_SYSVIPC.
- CONFIG_IPC_NS: [optional]
- PID_NS
- NET_NS
# Control groups are needed for better sandboxing of test processes.
- CGROUP_PIDS
- MEMCG
# Debugging features (from kernel_configs.md, do not alpha sort).
- DEBUG_BUGVERBOSE
- PANIC_ON_OOPS
- PANIC_TIMEOUT: 86400
- SCHED_STACK_END_CHECK
- FORTIFY_SOURCE: [-riscv, -clang]
- HARDENED_USERCOPY
- HARDENED_USERCOPY_FALLBACK: [-v5.15]
- BUG_ON_DATA_CORRUPTION
- DEBUG_LIST
- DEBUG_STACKOVERFLOW: [-v5.0]
# CONFIG_DEBUG_PI_LIST was renamed to CONFIG_DEBUG_PLIST in 8e18faeac3e4.
- DEBUG_PLIST: [v5.2]
- DEBUG_PI_LIST: [-v5.2]
# CONFIG_REFCOUNT_FULL was removed in fb041bb7c0a9.
- REFCOUNT_FULL: [v4.16, -v5.5]
# Added in 919067cc845f ("net: add CONFIG_PCPU_DEV_REFCNT") and should appear in v5.13.
- PCPU_DEV_REFCNT: [n, v5.13]
- NET_DEV_REFCNT_TRACKER: [v5.17]
- NET_NS_REFCNT_TRACKER: [v5.17]
# Added in 5.18 to aid network debugging.
- DEBUG_NET: [linux-next]
# This config does not add any debug checks (only debug output).
- DEBUG_KOBJECT: n
- DEBUG_INFO
# One of DEBUG_INFO_DWARF_* is required to enable DEBUG_INFO in v5.18.
- DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT: [v5.18]
# CONFIG_DEBUG_INFO_BTF breaks the build since 5.14 merge window:
# https://lkml.kernel.org/r/YOLzFecogWmdZ5Hc@infradead.org
- DEBUG_INFO_BTF: [-v5.13]
- DEBUG_INFO_REDUCED: n
# This should make behavior more deterministic.
- INIT_ON_ALLOC_DEFAULT_ON: [v4.16, -kmsan]
# KCOV slows down execution too much with KASAN_HW_TAGS and in qemu emulation in general.
# KCOV crashes on Arm:
# https://lore.kernel.org/linux-arm-kernel/20210119130010.GA2338@C02TD0UTHF1T.local/T/#m78fdfcc41ae831f91c93ad5dabe63f7ccfb482f0
# KCOV is not supported on s390 with our toolchain now, config depends on:
# (!ARCH_WANTS_NO_INSTR [=y] || STACK_VALIDATION [=n] || GCC_VERSION [=110200]>=120000 || CLANG_VERSION [=0]>=130000)
- KCOV: [-arm, -s390, -nokcov]
- KCOV_INSTRUMENT_ALL: [-arm, -s390, -nokcov]
- KCOV_ENABLE_COMPARISONS: [-arm, -s390, -nokcov]
- DEBUG_FS
# Required for KCOV but also eliminates unnecessary non-determinism.
- RELOCATABLE: n
- RANDOMIZE_BASE: n
# Print thread and CPU ids.
- PRINTK_CALLER
- PRINTK_TIME
# Some kernel oops'es are large. Largest observed for a stack overflow is ~42KB.
# There are 2 such buffers per CPU (safe and nmi), so this adds 128KB per CPU.
- PRINTK_SAFE_LOG_BUF_SHIFT: 16
# Fault injection.
- FAULT_INJECTION
- FAILSLAB
- FAIL_PAGE_ALLOC
- FAIL_MAKE_REQUEST
- FAIL_IO_TIMEOUT
- FAIL_FUTEX
- FAULT_INJECTION_DEBUG_FS
- FAULT_INJECTION_USERCOPY: [v5.10]
# Options enabled to boot Debian Wheezy.
- DEVTMPFS
- DEVTMPFS_MOUNT
- INOTIFY_USER
- UEVENT_HELPER
- UEVENT_HELPER_PATH: "/sbin/hotplug"
# QEMU disk is usually on the generic PCI bus.
- PCI_HOST_GENERIC: [v4.16]
- OF: [v4.16]
# Options enabled to boot Debian Stretch.
- CONFIGFS_FS
- SECURITYFS
# If syzkaller gets to /dev/{mem,kmem,ioport}, it will destroy the machine.
# It managed to do so with some mount's, chdir's and bogus file names.
# These are not needed for fuzzing, so completely disabling them is
# the simplest and the most reliable option.
- DEVMEM: n
- DEVKMEM: n
- DEVPORT: n
# Disable magic SysRq completely, as it can be reached over USB and through tty.
- MAGIC_SYSRQ: n
# We don't need it and it enables MAGIC_SYSRQ and KPROBES.
- KGDB: n
- RUNTIME_TESTING_MENU: n
# Don't test/need this (may be enabled via HID_HYPERV_MOUSE in USB/HID configs).
- HYPERV: n
# Don't test/need this.
- XEN: n
# These are legacy gadget drivers that we don't reach/test and some of these break boot:
# https://github.com/google/syzkaller/pull/1975#issuecomment-712807462
- USB_G_NCM: n
- USB_G_SERIAL: n
- USB_G_PRINTER: n
- USB_G_NOKIA: n
- USB_G_ACM_MS: n
- USB_G_MULTI: n
- USB_G_HID: n
- USB_G_DBGP: n
- USB_G_WEBCAM: n
- USB_ZERO: n
- USB_AUDIO: n
- USB_ETH: n
- USB_FUNCTIONFS: n
- USB_MASS_STORAGE: n
- USB_GADGET_TARGET: n
- USB_MIDI_GADGET: n
- USB_CDC_COMPOSITE: n
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