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15bc01effe
linux/kernel
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Eric W. Biederman 15bc01effe ucounts: Fix signal ucount refcounting 
In commit fda31c5029 ("signal: avoid double atomic counter
increments for user accounting") Linus made a clever optimization to
how rlimits and the struct user_struct.  Unfortunately that
optimization does not work in the obvious way when moved to nested
rlimits.  The problem is that the last decrement of the per user
namespace per user sigpending counter might also be the last decrement
of the sigpending counter in the parent user namespace as well.  Which
means that simply freeing the leaf ucount in __free_sigqueue is not
enough.

Maintain the optimization and handle the tricky cases by introducing
inc_rlimit_get_ucounts and dec_rlimit_put_ucounts.

By moving the entire optimization into functions that perform all of
the work it becomes possible to ensure that every level is handled
properly.

The new function inc_rlimit_get_ucounts returns 0 on failure to
increment the ucount.  This is different than inc_rlimit_ucounts which
increments the ucounts and returns LONG_MAX if the ucount counter has
exceeded it's maximum or it wrapped (to indicate the counter needs to
decremented).

I wish we had a single user to account all pending signals to across
all of the threads of a process so this complexity was not necessary

Cc: stable@vger.kernel.org
Fixes: d646969055 ("Reimplement RLIMIT_SIGPENDING on top of ucounts")
v1: https://lkml.kernel.org/r/87mtnavszx.fsf_-_@disp2133
Link: https://lkml.kernel.org/r/87fssytizw.fsf_-_@disp2133
Reviewed-by: Alexey Gladkov <legion@kernel.org>
Tested-by: Rune Kleveland <rune.kleveland@infomedia.dk>
Tested-by: Yu Zhao <yuzhao@google.com>
Tested-by: Jordan Glover <Golden_Miller83@protonmail.ch>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2021-10-18 16:02:30 -05:00
..
bpf bpf: Fix ringbuf helper function compatibility 2021-08-23 23:09:10 +02:00
cgroup cgroup: rstat: fix A-A deadlock on 32bit around u64_stats_sync 2021-07-27 13:12:20 -10:00
configs drivers/char: remove /dev/kmem for good 2021-05-07 00:26:34 -07:00
debug kernel: debug: Fix unreachable code in gdb_serial_stub() 2021-07-12 11:03:35 -05:00
dma dma-mapping: handle vmalloc addresses in dma_common_{mmap,get_sgtable} 2021-07-16 11:30:26 +02:00
entry tick/nohz: Only check for RCU deferred wakeup on user/guest entry when needed 2021-05-31 10:14:49 +02:00
events perf: Refactor permissions check into perf_check_permission() 2021-07-16 18:46:38 +02:00
gcov Kconfig: Introduce ARCH_WANTS_NO_INSTR and CC_HAS_NO_PROFILE_FN_ATTR 2021-06-22 11:07:18 -07:00
irq genirq/msi: Ensure deactivation on teardown 2021-08-10 15:55:19 +02:00
kcsan Merge branch 'kcsan.2021.05.18a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu 2021-07-04 12:29:16 -07:00
livepatch Livepatching changes for 5.13 2021-04-27 18:14:38 -07:00
locking locking/rtmutex: Use the correct rtmutex debugging config option 2021-08-10 08:21:52 +02:00
power PM: hibernate: disable when there are active secretmem users 2021-07-08 11:48:21 -07:00
printk printk changes for 5.14 2021-06-29 12:07:18 -07:00
rcu rcu: Fix pr_info() formats and values in show_rcu_gp_kthreads() 2021-07-06 15:53:12 -07:00
sched sched: Fix get_push_task() vs migrate_disable() 2021-08-26 19:02:00 +02:00
time timers: Move clearing of base::timer_running under base:: Lock 2021-07-27 20:57:44 +02:00
trace tracing: Limit the shooting in the foot of tp_printk 2021-08-17 09:47:18 -10:00
.gitignore .gitignore: prefix local generated files with a slash 2021-05-02 00:43:35 +09:00
acct.c kernel/acct.c: use #elif instead of #end and #elif 2020-12-15 22:46:15 -08:00
async.c kernel/async.c: remove async_unregister_domain() 2021-05-07 00:26:33 -07:00
audit_fsnotify.c audit_alloc_mark(): don't open-code ERR_CAST() 2021-02-23 10:25:27 -05:00
audit_tree.c audit: Use list_move instead of list_del/list_add 2021-06-08 22:18:35 -04:00
audit_watch.c fsnotify: generalize handle_inode_event() 2020-12-03 14:58:35 +01:00
audit.c lsm: separate security_task_getsecid() into subjective and objective variants 2021-03-22 15:23:32 -04:00
audit.h audit: remove trailing spaces and tabs 2021-06-10 20:59:05 -04:00
auditfilter.c lsm: separate security_task_getsecid() into subjective and objective variants 2021-03-22 15:23:32 -04:00
auditsc.c audit: remove trailing spaces and tabs 2021-06-10 20:59:05 -04:00
backtracetest.c
bounds.c
capability.c capability: handle idmapped mounts 2021-01-24 14:27:16 +01:00
cfi.c cfi: Use rcu_read_{un}lock_sched_notrace 2021-08-11 13:11:12 -07:00
compat.c
configs.c
context_tracking.c
cpu_pm.c
cpu.c A fix for the CPU hotplug and cpusets interaction: 2021-06-29 12:23:02 -07:00
crash_core.c kdump: use vmlinux_build_id to simplify 2021-07-08 11:48:22 -07:00
crash_dump.c
cred.c ucounts: Increase ucounts reference counter before the security hook 2021-08-23 16:13:04 -05:00
delayacct.c delayacct: Add sysctl to enable at runtime 2021-05-12 11:43:25 +02:00
dma.c
exec_domain.c
exit.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace 2021-06-28 20:39:26 -07:00
extable.c
fail_function.c fault-injection: handle EI_ETYPE_TRUE 2020-12-15 22:46:19 -08:00
fork.c ucounts: Fix regression preventing increasing of rlimits in init_user_ns 2021-08-23 16:10:42 -05:00
freezer.c sched: Add get_current_state() 2021-06-18 11:43:08 +02:00
futex.c Locking changes for this cycle: 2021-06-28 11:45:29 -07:00
gen_kheaders.sh kbuild: clean up ${quiet} checks in shell scripts 2021-05-27 04:01:50 +09:00
groups.c groups: simplify struct group_info allocation 2021-02-26 09:41:03 -08:00
hung_task.c Merge branch 'akpm' (patches from Andrew) 2021-07-02 12:08:10 -07:00
iomem.c
irq_work.c irq_work: Make irq_work_queue() NMI-safe again 2021-06-10 10:00:08 +02:00
jump_label.c jump_label: Fix jump_label_text_reserved() vs __init 2021-07-05 10:46:20 +02:00
kallsyms.c module: add printk formats to add module build ID to stacktraces 2021-07-08 11:48:22 -07:00
kcmp.c Merge branch 'exec-update-lock-for-v5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace 2020-12-15 19:36:48 -08:00
Kconfig.freezer
Kconfig.hz
Kconfig.locks
Kconfig.preempt sched/core: Disable CONFIG_SCHED_CORE by default 2021-06-28 22:43:05 +02:00
kcov.c kernel: make kcov_common_handle consider the current context 2020-11-02 18:00:20 -08:00
kexec_core.c kernel.h: split out panic and oops helpers 2021-07-01 11:06:04 -07:00
kexec_elf.c
kexec_file.c kernel: kexec_file: fix error return code of kexec_calculate_store_digests() 2021-05-07 00:26:32 -07:00
kexec_internal.h kexec: move machine_kexec_post_load() to public interface 2021-02-22 12:33:26 +00:00
kexec.c
kheaders.c
kmod.c modules: add CONFIG_MODPROBE_PATH 2021-05-07 00:26:33 -07:00
kprobes.c Locking fixes: 2021-07-11 11:06:09 -07:00
ksysfs.c
kthread.c Merge branch 'akpm' (patches from Andrew) 2021-06-29 17:29:11 -07:00
latencytop.c
Makefile kbuild: update config_data.gz only when the content of .config is changed 2021-05-02 00:43:35 +09:00
module_signature.c module: harden ELF info handling 2021-01-19 10:24:45 +01:00
module_signing.c module: harden ELF info handling 2021-01-19 10:24:45 +01:00
module-internal.h
module.c module: add printk formats to add module build ID to stacktraces 2021-07-08 11:48:22 -07:00
notifier.c
nsproxy.c fixes-v5.11 2020-12-14 16:40:27 -08:00
padata.c
panic.c kernel.h: split out panic and oops helpers 2021-07-01 11:06:04 -07:00
params.c Modules updates for v5.11 2020-12-17 13:01:31 -08:00
pid_namespace.c fixes-v5.11 2020-12-14 16:40:27 -08:00
pid.c Merge branch 'exec-update-lock-for-v5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace 2020-12-15 19:36:48 -08:00
profile.c kernel: Initialize cpumask before parsing 2021-04-10 13:35:54 +02:00
ptrace.c sched: Change task_struct::state 2021-06-18 11:43:09 +02:00
range.c kernel.h: split out min()/max() et al. helpers 2020-10-16 11:11:19 -07:00
reboot.c reboot: Add hardware protection power-off 2021-06-21 13:08:36 +01:00
regset.c
relay.c relay: allow the use of const callback structs 2020-12-15 22:46:18 -08:00
resource_kunit.c resource: provide meaningful MODULE_LICENSE() in test suite 2020-11-25 18:52:35 +01:00
resource.c kernel/resource: fix return code check in __request_free_mem_region 2021-05-14 19:41:32 -07:00
rseq.c rseq: Optimise rseq_get_rseq_cs() and clear_rseq_cs() 2021-04-14 18:04:09 +02:00
scftorture.c scftorture: Avoid false-positive warnings in scftorture_invoker() 2021-07-06 12:37:55 -07:00
scs.c scs: switch to vmapped shadow stacks 2020-12-01 10:30:28 +00:00
seccomp.c seccomp: Fix setting loaded filter count during TSYNC 2021-08-11 11:48:28 -07:00
signal.c ucounts: Fix signal ucount refcounting 2021-10-18 16:02:30 -05:00
smp.c smp: Fix smp_call_function_single_async prototype 2021-05-06 15:33:49 +02:00
smpboot.c smpboot: fix duplicate and misplaced inlining directive 2021-07-25 11:06:37 -07:00
smpboot.h
softirq.c sched: Introduce task_is_running() 2021-06-18 11:43:07 +02:00
stackleak.c
stacktrace.c
static_call.c static_call: Fix static_call_text_reserved() vs __init 2021-07-05 10:46:33 +02:00
stop_machine.c stop_machine: Add caller debug info to queue_stop_cpus_work 2021-03-23 16:01:58 +01:00
sys_ni.c mm: introduce memfd_secret system call to create "secret" memory areas 2021-07-08 11:48:21 -07:00
sys.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace 2021-06-28 20:39:26 -07:00
sysctl-test.c kernel/sysctl-test: Remove some casts which are no-longer required 2021-06-23 16:41:24 -06:00
sysctl.c Merge branch 'akpm' (patches from Andrew) 2021-07-02 12:08:10 -07:00
task_work.c kasan: record task_work_add() call stack 2021-04-30 11:20:42 -07:00
taskstats.c treewide: rename nla_strlcpy to nla_strscpy. 2020-11-16 08:08:54 -08:00
test_kprobes.c
torture.c torture: Replace torture_init_begin string with %s 2021-03-08 14:22:28 -08:00
tracepoint.c tracepoint: Use rcu get state and cond sync for static call updates 2021-08-06 10:54:41 -04:00
tsacct.c
ucount.c ucounts: Fix signal ucount refcounting 2021-10-18 16:02:30 -05:00
uid16.c
uid16.h
umh.c kernel/umh.c: fix some spelling mistakes 2021-05-07 00:26:34 -07:00
up.c A set of locking related fixes and updates: 2021-05-09 13:07:03 -07:00
user_namespace.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace 2021-06-28 20:39:26 -07:00
user-return-notifier.c
user.c Reimplement RLIMIT_MEMLOCK on top of ucounts 2021-04-30 14:14:02 -05:00
usermode_driver.c Merge branch 'work.namei' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2021-07-03 11:41:14 -07:00
utsname_sysctl.c
utsname.c
watch_queue.c watch_queue: rectify kernel-doc for init_watch() 2021-01-26 11:16:34 +00:00
watchdog_hld.c
watchdog.c kernel: watchdog: modify the explanation related to watchdog thread 2021-06-29 10:53:46 -07:00
workqueue_internal.h
workqueue.c workqueue: fix UAF in pwq_unbound_release_workfn() 2021-07-21 06:42:31 -10:00