Eric W. Biederman
7146db3317
signal: Better detection of synchronous signals
...
Recently syzkaller was able to create unkillablle processes by
creating a timer that is delivered as a thread local signal on SIGHUP,
and receiving SIGHUP SA_NODEFERER. Ultimately causing a loop failing
to deliver SIGHUP but always trying.
When the stack overflows delivery of SIGHUP fails and force_sigsegv is
called. Unfortunately because SIGSEGV is numerically higher than
SIGHUP next_signal tries again to deliver a SIGHUP.
From a quality of implementation standpoint attempting to deliver the
timer SIGHUP signal is wrong. We should attempt to deliver the
synchronous SIGSEGV signal we just forced.
We can make that happening in a fairly straight forward manner by
instead of just looking at the signal number we also look at the
si_code. In particular for exceptions (aka synchronous signals) the
si_code is always greater than 0.
That still has the potential to pick up a number of asynchronous
signals as in a few cases the same si_codes that are used
for synchronous signals are also used for asynchronous signals,
and SI_KERNEL is also included in the list of possible si_codes.
Still the heuristic is much better and timer signals are definitely
excluded. Which is enough to prevent all known ways for someone
sending a process signals fast enough to cause unexpected and
arguably incorrect behavior.
Cc: stable@vger.kernel.org
Fixes: a27341cd5f ("Prioritize synchronous signals over 'normal' signals")
Tested-by: Dmitry Vyukov <dvyukov@google.com>
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2019-02-07 09:00:36 -06:00
..
bpf
Remove 'type' argument from access_ok() function
2019-01-03 18:57:57 -08:00
cgroup
Merge branch 'for-4.21' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
2018-12-29 10:57:20 -08:00
configs
kvm_config: add CONFIG_VIRTIO_MENU
2018-10-24 20:55:56 -04:00
debug
kdb: use bool for binary state indicators
2018-12-30 08:31:52 +00:00
dma
dma-direct: fix DMA_ATTR_NO_KERNEL_MAPPING for remapped allocations
2019-01-05 08:28:29 +01:00
events
Remove 'type' argument from access_ok() function
2019-01-03 18:57:57 -08:00
gcov
irq
genirq/affinity: Add is_managed to struct irq_affinity_desc
2018-12-19 11:32:08 +01:00
livepatch
livepatch: Replace synchronize_sched() with synchronize_rcu()
2018-12-01 12:38:50 -08:00
locking
kernel/locking/mutex.c: remove caller signal_pending branch predictions
2019-01-04 13:13:48 -08:00
power
mm: convert totalram_pages and totalhigh_pages variables to atomic
2018-12-28 12:11:47 -08:00
printk
Remove 'type' argument from access_ok() function
2019-01-03 18:57:57 -08:00
rcu
rcutorture: Don't do busted forward-progress testing
2018-12-01 12:45:42 -08:00
sched
jump_label: move 'asm goto' support test to Kconfig
2019-01-06 09:46:51 +09:00
time
y2038: more syscalls and cleanups
2018-12-28 12:45:04 -08:00
trace
Remove 'type' argument from access_ok() function
2019-01-03 18:57:57 -08:00
.gitignore
acct.c
async.c
audit.c
audit: remove duplicated include from audit.c
2018-12-14 12:09:30 -05:00
audit.h
audit: use current whenever possible
2018-11-26 18:41:21 -05:00
audit_fsnotify.c
audit: minimize our use of audit_log_format()
2018-11-26 18:40:00 -05:00
audit_tree.c
audit: minimize our use of audit_log_format()
2018-11-26 18:40:00 -05:00
audit_watch.c
audit: minimize our use of audit_log_format()
2018-11-26 18:40:00 -05:00
auditfilter.c
auditsc.c
audit: use current whenever possible
2018-11-26 18:41:21 -05:00
backtracetest.c
bounds.c
kbuild: fix kernel/bounds.c 'W=1' warning
2018-10-31 08:54:14 -07:00
capability.c
compat.c
make 'user_access_begin()' do 'access_ok()'
2019-01-04 12:56:09 -08:00
configs.c
context_tracking.c
cpu.c
x86/speculation: Rework SMT state change
2018-11-28 11:57:07 +01:00
cpu_pm.c
crash_core.c
kernel/crash_core.c: print timestamp using time64_t
2018-08-22 10:52:47 -07:00
crash_dump.c
cred.c
cred: export get_task_cred().
2018-12-19 13:52:44 -05:00
delayacct.c
delayacct: track delays from thrashing cache pages
2018-10-26 16:26:32 -07:00
dma.c
elfcore.c
exec_domain.c
exit.c
make 'user_access_begin()' do 'access_ok()'
2019-01-04 12:56:09 -08:00
extable.c
fail_function.c
kernel/fail_function.c: remove meaningless null pointer check before debugfs_remove_recursive
2018-10-31 08:54:12 -07:00
fork.c
fork: fix some -Wmissing-prototypes warnings
2019-01-04 13:13:47 -08:00
freezer.c
PM / reboot: Eliminate race between reboot and suspend
2018-08-06 12:35:20 +02:00
futex.c
Remove 'type' argument from access_ok() function
2019-01-03 18:57:57 -08:00
groups.c
hung_task.c
kernel/hung_task.c: break RCU locks based on jiffies
2019-01-04 13:13:45 -08:00
iomem.c
irq_work.c
jump_label.c
jump_label: move 'asm goto' support test to Kconfig
2019-01-06 09:46:51 +09:00
kallsyms.c
kallsyms: reduce size a little on 64-bit
2018-09-10 22:54:33 +09:00
kcmp.c
Kconfig.freezer
Kconfig.hz
Kconfig.locks
Kconfig.preempt
kconfig: warn no new line at end of file
2018-12-15 17:44:35 +09:00
kcov.c
kernel/kcov.c: mark write_comp_data() as notrace
2019-01-04 13:13:47 -08:00
kexec.c
kexec: add call to LSM hook in original kexec_load syscall
2018-07-16 12:31:57 -07:00
kexec_core.c
mm: convert totalram_pages and totalhigh_pages variables to atomic
2018-12-28 12:11:47 -08:00
kexec_file.c
kexec_file: kexec_walk_memblock() only walks a dedicated region at kdump
2018-12-06 14:38:50 +00:00
kexec_internal.h
kmod.c
kprobes.c
Merge branch 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
2018-12-26 14:45:18 -08:00
ksysfs.c
kthread.c
Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
2018-08-13 11:25:07 -07:00
latencytop.c
Makefile
kbuild: change filechk to surround the given command with { }
2019-01-06 09:46:51 +09:00
memremap.c
mm/hmm: fix memremap.h, move dev_page_fault_t callback to hmm
2018-12-28 12:11:52 -08:00
module-internal.h
module.c
jump_label: move 'asm goto' support test to Kconfig
2019-01-06 09:46:51 +09:00
module_signing.c
modsign: use all trusted keys to verify module signature
2018-11-07 14:41:41 +01:00
notifier.c
nsproxy.c
padata.c
padata: clean an indentation issue, remove extraneous space
2018-11-16 14:11:04 +08:00
panic.c
kernel/sysctl: add panic_print into sysctl
2019-01-04 13:13:47 -08:00
params.c
pid.c
Fix failure path in alloc_pid()
2018-12-28 12:42:30 -08:00
pid_namespace.c
signal: Use group_send_sig_info to kill all processes in a pid namespace
2018-09-16 16:08:25 +02:00
profile.c
mm: remove include/linux/bootmem.h
2018-10-31 08:54:16 -07:00
ptrace.c
Remove 'type' argument from access_ok() function
2019-01-03 18:57:57 -08:00
range.c
reboot.c
kernel/reboot.c: export pm_power_off_prepare
2018-09-11 16:13:24 +01:00
relay.c
resource.c
kernel, resource: check for IORESOURCE_SYSRAM in release_mem_region_adjustable
2018-12-28 12:11:49 -08:00
rseq.c
Remove 'type' argument from access_ok() function
2019-01-03 18:57:57 -08:00
seccomp.c
seccomp: fix poor type promotion
2018-12-13 16:49:01 -08:00
signal.c
signal: Better detection of synchronous signals
2019-02-07 09:00:36 -06:00
smp.c
smp,cpumask: introduce on_each_cpu_cond_mask
2018-10-09 16:51:11 +02:00
smpboot.c
smpboot.h
softirq.c
Merge branch 'irq-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
2018-10-25 11:43:47 -07:00
stackleak.c
stackleak: Mark stackleak_track_stack() as notrace
2018-12-05 19:31:44 -08:00
stacktrace.c
stop_machine.c
Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
2018-08-13 11:25:07 -07:00
sys.c
Remove 'type' argument from access_ok() function
2019-01-03 18:57:57 -08:00
sys_ni.c
y2038: socket: Add compat_sys_recvmmsg_time64
2018-12-18 16:13:04 +01:00
sysctl.c
kernel/sysctl: add panic_print into sysctl
2019-01-04 13:13:47 -08:00
sysctl_binary.c
kernel/sysctl: add panic_print into sysctl
2019-01-04 13:13:47 -08:00
task_work.c
taskstats.c
test_kprobes.c
torture.c
torture: Remove unnecessary "ret" variables
2018-12-01 12:45:35 -08:00
tracepoint.c
tracing: Replace synchronize_sched() and call_rcu_sched()
2018-11-27 09:21:41 -08:00
tsacct.c
ucount.c
uid16.c
uid16.h
umh.c
umh: Add command line to user mode helpers
2018-10-22 19:37:36 -07:00
up.c
smp,cpumask: introduce on_each_cpu_cond_mask
2018-10-09 16:51:11 +02:00
user-return-notifier.c
user.c
userns: use irqsave variant of refcount_dec_and_lock()
2018-08-22 10:52:47 -07:00
user_namespace.c
userns: also map extents in the reverse map to kernel IDs
2018-11-07 23:51:16 -06:00
utsname.c
utsname_sysctl.c
sys: don't hold uts_sem while accessing userspace memory
2018-08-11 02:05:53 -05:00
watchdog.c
watchdog: Mark watchdog touch functions as notrace
2018-08-30 12:56:40 +02:00
watchdog_hld.c
watchdog: Mark watchdog touch functions as notrace
2018-08-30 12:56:40 +02:00
workqueue.c
workqueue: Replace call_rcu_sched() with call_rcu()
2018-11-27 09:21:44 -08:00
workqueue_internal.h