Kees Cook
e01e80634e
fork: unconditionally clear stack on fork
...
One of the classes of kernel stack content leaks[1] is exposing the
contents of prior heap or stack contents when a new process stack is
allocated. Normally, those stacks are not zeroed, and the old contents
remain in place. In the face of stack content exposure flaws, those
contents can leak to userspace.
Fixing this will make the kernel no longer vulnerable to these flaws, as
the stack will be wiped each time a stack is assigned to a new process.
There's not a meaningful change in runtime performance; it almost looks
like it provides a benefit.
Performing back-to-back kernel builds before:
Run times: 157.86 157.09 158.90 160.94 160.80
Mean: 159.12
Std Dev: 1.54
and after:
Run times: 159.31 157.34 156.71 158.15 160.81
Mean: 158.46
Std Dev: 1.46
Instead of making this a build or runtime config, Andy Lutomirski
recommended this just be enabled by default.
[1] A noisy search for many kinds of stack content leaks can be seen here:
https://cve.mitre.org/cgi-bin/cvekey.cgi?keyword=linux+kernel+stack+leak
I did some more with perf and cycle counts on running 100,000 execs of
/bin/true.
before:
Cycles: 218858861551 218853036130 214727610969 227656844122 224980542841
Mean: 221015379122.60
Std Dev: 4662486552.47
after:
Cycles: 213868945060 213119275204 211820169456 224426673259 225489986348
Mean: 217745009865.40
Std Dev: 5935559279.99
It continues to look like it's faster, though the deviation is rather
wide, but I'm not sure what I could do that would be less noisy. I'm
open to ideas!
Link: http://lkml.kernel.org/r/20180221021659.GA37073@beast
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Laura Abbott <labbott@redhat.com>
Cc: Rasmus Villemoes <rasmus.villemoes@prevas.dk>
Cc: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-04-20 17:18:35 -07:00
..
bpf
kernel/bpf/syscall: fix warning defined but not used
2018-04-04 11:08:36 +02:00
cgroup
Merge branch 'for-4.17' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq
2018-04-03 18:00:13 -07:00
configs
KVM changes for 4.16
2018-02-10 13:16:35 -08:00
debug
* Fix 2032 time access issues and new compiler warnings
2018-04-12 10:21:19 -07:00
events
perf/core: Need CAP_SYS_ADMIN to create k/uprobe with perf_event_open()
2018-04-12 09:55:50 +02:00
gcov
License cleanup: add SPDX GPL-2.0 license identifier to files with no license
2017-11-02 11:10:55 +01:00
irq
genirq/affinity: Spread irq vectors among present CPUs as far as possible
2018-04-06 12:19:51 +02:00
livepatch
livepatch: Allow to call a custom callback when freeing shadow variables
2018-04-17 13:42:48 +02:00
locking
locking/rwsem: Add DEBUG_RWSEMS to look for lock/unlock mismatches
2018-03-31 07:30:50 +02:00
power
PM / QoS: mark expected switch fall-throughs
2018-04-09 13:49:40 +02:00
printk
New features:
2018-04-10 11:27:30 -07:00
rcu
Merge branches 'fixes.2018.02.23a', 'srcu.2018.02.20a' and 'torture.2018.02.20a' into HEAD
2018-02-23 15:15:41 -08:00
sched
Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
2018-04-15 12:43:30 -07:00
time
Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
2018-04-15 16:12:35 -07:00
trace
Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
2018-04-15 12:36:31 -07:00
.gitignore
acct.c
kernel/acct.c: fix the acct->needcheck check in check_free_space()
2018-01-04 16:45:09 -08:00
async.c
kernel/async.c: revert "async: simplify lowest_in_progress()"
2018-02-06 18:32:44 -08:00
audit.c
audit/stable-4.17 PR 20180403
2018-04-06 15:01:25 -07:00
audit.h
audit: track the owner of the command mutex ourselves
2018-02-23 11:22:22 -05:00
audit_fsnotify.c
audit_tree.c
audit: track the owner of the command mutex ourselves
2018-02-23 11:22:22 -05:00
audit_watch.c
auditfilter.c
audit: deprecate the AUDIT_FILTER_ENTRY filter
2018-02-15 14:36:29 -05:00
auditsc.c
audit: bail before bug check if audit disabled
2018-02-15 14:40:25 -05:00
backtracetest.c
bounds.c
License cleanup: add SPDX GPL-2.0 license identifier to files with no license
2017-11-02 11:10:55 +01:00
capability.c
License cleanup: add SPDX GPL-2.0 license identifier to files with no license
2017-11-02 11:10:55 +01:00
compat.c
mm: add kernel_move_pages() helper, move compat syscall to mm/migrate.c
2018-04-02 20:15:32 +02:00
configs.c
context_tracking.c
cpu.c
cpu/hotplug: Fix unused function warning
2018-03-15 20:34:40 +01:00
cpu_pm.c
crash_core.c
kexec: export PG_swapbacked to VMCOREINFO
2018-04-13 17:10:27 -07:00
crash_dump.c
cred.c
delayacct.c
delayacct: Account blkio completion on the correct task
2018-01-16 03:29:36 +01:00
dma.c
License cleanup: add SPDX GPL-2.0 license identifier to files with no license
2017-11-02 11:10:55 +01:00
elfcore.c
License cleanup: add SPDX GPL-2.0 license identifier to files with no license
2017-11-02 11:10:55 +01:00
exec_domain.c
get rid of pointless includes of fs_struct.h
2018-02-22 14:28:50 -05:00
exit.c
kernel: use kernel_wait4() instead of sys_wait4()
2018-04-02 20:14:51 +02:00
extable.c
extable: Make init_kernel_text() global
2018-02-21 16:54:06 +01:00
fail_function.c
error-injection: Fix to prohibit jump optimization
2018-03-12 16:16:00 +01:00
fork.c
fork: unconditionally clear stack on fork
2018-04-20 17:18:35 -07:00
freezer.c
futex.c
pids: introduce find_get_task_by_vpid() helper
2018-02-06 18:32:46 -08:00
futex_compat.c
License cleanup: add SPDX GPL-2.0 license identifier to files with no license
2017-11-02 11:10:55 +01:00
groups.c
kernel: make groups_sort calling a responsibility group_info allocators
2017-12-14 16:00:49 -08:00
hung_task.c
irq_work.c
irq/work: Improve the flag definitions
2018-01-08 19:43:15 +01:00
jump_label.c
jump_label: Disable jump labels in __exit code
2018-03-20 08:57:17 +01:00
kallsyms.c
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/pmladek/printk
2018-02-01 13:36:15 -08:00
kcmp.c
License cleanup: add SPDX GPL-2.0 license identifier to files with no license
2017-11-02 11:10:55 +01:00
Kconfig.freezer
Kconfig.hz
Kconfig.locks
Kconfig.preempt
kcov.c
kcov: detect double association with a single task
2018-02-06 18:32:46 -08:00
kexec.c
kexec: call do_kexec_load() in compat syscall directly
2018-04-02 20:15:01 +02:00
kexec_core.c
kexec_file.c
kernel/kexec_file.c: allow archs to set purgatory load address
2018-04-13 17:10:28 -07:00
kexec_internal.h
License cleanup: add SPDX GPL-2.0 license identifier to files with no license
2017-11-02 11:10:55 +01:00
kmod.c
kprobes.c
kprobes: Propagate error from disarm_kprobe_ftrace()
2018-02-16 09:12:58 +01:00
ksysfs.c
kthread.c
treewide: Remove TIMER_FUNC_TYPE and TIMER_DATA_TYPE casts
2017-11-21 16:35:54 -08:00
latencytop.c
Makefile
error-injection: Support fault injection framework
2018-01-12 17:33:38 -08:00
memremap.c
kernel/memremap: Remove stale devres_free() call
2018-03-06 10:58:54 -08:00
module-internal.h
module.c
arch: remove obsolete architecture ports
2018-04-02 20:20:12 -07:00
module_signing.c
notifier.c
nsproxy.c
padata.c
padata: add SPDX identifier
2018-01-05 18:43:00 +11:00
panic.c
taint: add taint for randstruct
2018-04-11 10:28:35 -07:00
params.c
kernel/params.c: downgrade warning for unsafe parameters
2018-04-11 10:28:37 -07:00
pid.c
xarray: add the xa_lock to the radix_tree_root
2018-04-11 10:28:39 -07:00
pid_namespace.c
Merge branch 'userns-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace
2018-04-03 19:15:32 -07:00
profile.c
ptrace.c
pids: introduce find_get_task_by_vpid() helper
2018-02-06 18:32:46 -08:00
range.c
License cleanup: add SPDX GPL-2.0 license identifier to files with no license
2017-11-02 11:10:55 +01:00
reboot.c
kernel/reboot.c: add devm_register_reboot_notifier()
2017-11-17 16:10:04 -08:00
relay.c
kernel/relay.c: limit kmalloc size to KMALLOC_MAX_SIZE
2018-02-21 15:35:43 -08:00
resource.c
resource: fix integer overflow at reallocation
2018-04-13 17:10:27 -07:00
seccomp.c
- Fix seccomp GET_METADATA to deal with field sizes correctly (Tycho Andersen)
2018-02-22 10:50:24 -08:00
signal.c
Merge branch 'next-general' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security
2018-04-07 11:11:41 -07:00
smp.c
smp/core: Use lockdep to assert IRQs are disabled/enabled
2017-11-08 11:13:50 +01:00
smpboot.c
smpboot.h
License cleanup: add SPDX GPL-2.0 license identifier to files with no license
2017-11-02 11:10:55 +01:00
softirq.c
softirq: Consolidate common code in tasklet_[hi]_action()
2018-03-09 11:50:55 +01:00
stacktrace.c
stop_machine.c
sys.c
kernel: add ksys_setsid() helper; remove in-kernel call to sys_setsid()
2018-04-02 20:16:06 +02:00
sys_ni.c
syscalls/core: Prepare CONFIG_ARCH_HAS_SYSCALL_WRAPPER=y for compat syscalls
2018-04-05 16:59:38 +02:00
sysctl.c
kernel/sysctl.c: add kdoc comments to do_proc_do{u}intvec_minmax_conv_param
2018-04-11 10:28:38 -07:00
sysctl_binary.c
License cleanup: add SPDX GPL-2.0 license identifier to files with no license
2017-11-02 11:10:55 +01:00
task_work.c
locking/barriers: Convert users of lockless_dereference() to READ_ONCE()
2017-12-17 13:57:15 +01:00
taskstats.c
pids: introduce find_get_task_by_vpid() helper
2018-02-06 18:32:46 -08:00
test_kprobes.c
kprobes: Disable the jprobes test code
2017-10-20 11:02:54 +02:00
torture.c
torture: Save a line in stutter_wait(): while -> for
2017-12-11 09:18:30 -08:00
tracepoint.c
tracepoint: Remove smp_read_barrier_depends() from comment
2017-12-04 10:52:56 -08:00
tsacct.c
ucount.c
headers: untangle kmemleak.h from mm.h
2018-04-05 21:36:27 -07:00
uid16.c
fs: add do_fchownat(), ksys_fchown() helpers and ksys_{,l}chown() wrappers
2018-04-02 20:15:59 +02:00
uid16.h
kernel: provide ksys_*() wrappers for syscalls called by kernel/uid16.c
2018-04-02 20:15:30 +02:00
umh.c
kernel: use kernel_wait4() instead of sys_wait4()
2018-04-02 20:14:51 +02:00
up.c
user-return-notifier.c
user.c
efivarfs: Limit the rate for non-root to read files
2018-02-22 10:21:02 -08:00
user_namespace.c
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace
2017-11-16 12:20:15 -08:00
utsname.c
uts: create "struct uts_namespace" from kmem_cache
2018-04-11 10:28:35 -07:00
utsname_sysctl.c
watchdog.c
Merge branch 'linus' into sched/core, to pick up fixes
2017-11-08 10:17:15 +01:00
watchdog_hld.c
Merge branch 'linus' into core/urgent, to pick up dependent commits
2017-11-04 08:53:04 +01:00
workqueue.c
Merge branch 'for-4.17' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq
2018-04-03 18:00:13 -07:00
workqueue_internal.h
Merge branch 'for-4.14-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq
2017-11-06 12:26:49 -08:00