Kumar Kartikeya Dwivedi 275c30bcee bpf: Don't reinit map value in prealloc_lru_pop ... The LRU map that is preallocated may have its elements reused while another program holds a pointer to it from bpf_map_lookup_elem. Hence, only check_and_free_fields is appropriate when the element is being deleted, as it ensures proper synchronization against concurrent access of the map value. After that, we cannot call check_and_init_map_value again as it may rewrite bpf_spin_lock, bpf_timer, and kptr fields while they can be concurrently accessed from a BPF program. This is safe to do as when the map entry is deleted, concurrent access is protected against by check_and_free_fields, i.e. an existing timer would be freed, and any existing kptr will be released by it. The program can create further timers and kptrs after check_and_free_fields, but they will eventually be released once the preallocated items are freed on map destruction, even if the item is never reused again. Hence, the deleted item sitting in the free list can still have resources attached to it, and they would never leak. With spin_lock, we never touch the field at all on delete or update, as we may end up modifying the state of the lock. Since the verifier ensures that a bpf_spin_lock call is always paired with bpf_spin_unlock call, the program will eventually release the lock so that on reuse the new user of the value can take the lock. Essentially, for the preallocated case, we must assume that the map value may always be in use by the program, even when it is sitting in the freelist, and handle things accordingly, i.e. use proper synchronization inside check_and_free_fields, and never reinitialize the special fields when it is reused on update. Fixes: 68134668c1 ("bpf: Add map side support for bpf timers.") Acked-by: Yonghong Song <yhs@fb.com> Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com> Acked-by: Martin KaFai Lau <kafai@fb.com> Link: https://lore.kernel.org/r/20220809213033.24147-3-memxor@gmail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>		2022-08-09 18:46:11 -07:00
..
bpf	bpf: Don't reinit map value in prealloc_lru_pop	2022-08-09 18:46:11 -07:00
cgroup	Several core optimizations:	2022-08-03 09:45:08 -07:00
configs	x86/configs: Update configs in x86_debug.config	2022-07-27 18:09:11 +02:00
debug	Modules updates for v5.19-rc1	2022-05-26 17:13:43 -07:00
dma	dma-direct: use the correct size for dma_set_encrypted()	2022-06-23 15:26:59 +02:00
entry	context_tracking: Take NMI eqs entrypoints over RCU	2022-07-05 13:32:59 -07:00
events	Networking changes for 6.0.	2022-08-03 16:29:08 -07:00
futex	drm for 5.19-rc1	2022-05-25 16:18:27 -07:00
gcov	gcov: Remove compiler version check	2021-12-02 17:25:21 +09:00
irq	irqchip/genirq updates for 5.20:	2022-07-28 12:36:35 +02:00
kcsan	kcsan: test: Add a .kunitconfig to run KCSAN tests	2022-07-22 09:22:59 -06:00
livepatch	Livepatching changes for 5.19	2022-06-02 08:55:01 -07:00
locking	RCU pull request for v5.20 (or whatever)	2022-08-02 19:12:45 -07:00
module	linux-kselftest-kunit-5.20-rc1	2022-08-02 19:34:45 -07:00
power	for-5.20/block-2022-07-29	2022-08-02 13:46:35 -07:00
printk	printk: do not wait for consoles when suspended	2022-07-15 10:52:11 +02:00
rcu	RCU pull request for v5.20 (or whatever)	2022-08-02 19:12:45 -07:00
sched	Several core optimizations:	2022-08-03 09:45:08 -07:00
time	Networking changes for 6.0.	2022-08-03 16:29:08 -07:00
trace	Networking changes for 6.0.	2022-08-03 16:29:08 -07:00
.gitignore
acct.c	kernel/acct: move acct sysctls to its own file	2022-04-06 13:43:44 -07:00
async.c	Revert "module, async: async_synchronize_full() on module init iff async is used"	2022-02-03 11:20:34 -08:00
audit_fsnotify.c	fsnotify: make allow_dups a property of the group	2022-04-25 14:37:18 +02:00
audit_tree.c	audit: use fsnotify group lock helpers	2022-04-25 14:37:28 +02:00
audit_watch.c	fsnotify: pass flags argument to fsnotify_alloc_group()	2022-04-25 14:37:12 +02:00
audit.c	audit: make is_audit_feature_set() static	2022-06-13 14:08:57 -04:00
audit.h	audit: log AUDIT_TIME_* records only from rules	2022-02-22 13:51:40 -05:00
auditfilter.c	audit/stable-5.17 PR 20220110	2022-01-11 13:08:21 -08:00
auditsc.c	audit: free module name	2022-06-15 19:28:44 -04:00
backtracetest.c
bounds.c
capability.c	xfs: don't generate selinux audit messages for capability testing	2022-03-09 10:32:06 -08:00
cfi.c	context_tracking: Take IRQ eqs entrypoints over RCU	2022-07-05 13:32:59 -07:00
compat.c
configs.c
context_tracking.c	MAINTAINERS: Add Paul as context tracking maintainer	2022-07-05 13:33:00 -07:00
cpu_pm.c	context_tracking: Take IRQ eqs entrypoints over RCU	2022-07-05 13:32:59 -07:00
cpu.c	Intel Trust Domain Extensions	2022-05-23 17:51:12 -07:00
crash_core.c	Not a lot of material this cycle. Many singleton patches against various	2022-05-27 11:22:03 -07:00
crash_dump.c
cred.c	x86: Mark __invalid_creds() __noreturn	2022-03-15 10:32:44 +01:00
delayacct.c	delayacct: track delays from write-protect copy	2022-06-01 15:55:25 -07:00
dma.c
exec_domain.c
exit.c	fix race between exit_itimers() and /proc/pid/timers	2022-07-11 09:52:59 -07:00
extable.c	context_tracking: Take NMI eqs entrypoints over RCU	2022-07-05 13:32:59 -07:00
fail_function.c
fork.c	RCU pull request for v5.20 (or whatever)	2022-08-02 19:12:45 -07:00
freezer.c
gen_kheaders.sh	kheaders: Have cpio unconditionally replace files	2022-05-08 03:16:59 +09:00
groups.c	security: Add LSM hook to setgroups() syscall	2022-07-15 18:21:49 +00:00
hung_task.c	Merge branch 'rework/kthreads' into for-linus	2022-06-23 19:11:28 +02:00
iomem.c
irq_work.c	irq_work: use kasan_record_aux_stack_noalloc() record callstack	2022-04-15 14:49:55 -07:00
jump_label.c	jump_label: make initial NOP patching the special case	2022-06-24 09:48:55 +02:00
kallsyms.c	bpf: add a ksym BPF iterator	2022-07-12 15:27:19 -07:00
kcmp.c
Kconfig.freezer
Kconfig.hz
Kconfig.locks
Kconfig.preempt	Revert "signal, x86: Delay calling signals in atomic on RT enabled kernels"	2022-03-31 10:36:55 +02:00
kcov.c	kcov: update pos before writing pc in trace function	2022-05-25 13:05:42 -07:00
kexec_core.c	kexec: drop weak attribute from functions	2022-07-15 12:21:16 -04:00
kexec_elf.c
kexec_file.c	kexec, KEYS: make the code in bzImage64_verify_sig generic	2022-07-15 12:21:16 -04:00
kexec_internal.h
kexec.c
kheaders.c
kmod.c
kprobes.c	tracing updates for 5.19:	2022-05-29 10:31:36 -07:00
ksysfs.c	kernel/ksysfs.c: use helper macro __ATTR_RW	2022-03-23 19:00:33 -07:00
kthread.c	kthread: make it clear that kthread_create_on_node() might be terminated by any fatal signal	2022-06-16 19:11:30 -07:00
latencytop.c	latencytop: move sysctl to its own file	2022-04-21 11:40:59 -07:00
Makefile	kernel: add platform_has() infrastructure	2022-06-06 08:06:00 +02:00
module_signature.c
notifier.c	notifier: Add blocking/atomic_notifier_chain_register_unique_prio()	2022-05-19 19:30:30 +02:00
nsproxy.c	fs/exec: allow to unshare a time namespace on vfork+exec	2022-06-15 07:58:04 -07:00
padata.c	padata: replace cpumask_weight with cpumask_empty in padata.c	2022-01-31 11:21:46 +11:00
panic.c	linux-kselftest-kunit-5.20-rc1	2022-08-02 19:34:45 -07:00
params.c	kobject: remove kset from struct kset_uevent_ops callbacks	2021-12-28 11:26:18 +01:00
pid_namespace.c	kernel: pid_namespace: use NULL instead of using plain integer as pointer	2022-04-29 14:38:00 -07:00
pid.c	pid: add pidfd_get_task() helper	2021-10-14 13:29:18 +02:00
platform-feature.c	kernel: add platform_has() infrastructure	2022-06-06 08:06:00 +02:00
profile.c	exit: Remove profile_handoff_task	2022-01-08 12:43:57 -06:00
ptrace.c	ptrace: fix clearing of JOBCTL_TRACED in ptrace_unfreeze_traced()	2022-07-09 11:06:19 -07:00
range.c
reboot.c	Merge branch 'rework/kthreads' into for-linus	2022-06-23 19:11:28 +02:00
regset.c
relay.c	relay: remove redundant assignment to pointer buf	2022-05-12 20:38:37 -07:00
resource_kunit.c
resource.c	kernel/resource: fix kfree() of bootmem memory again	2022-03-23 19:00:35 -07:00
rseq.c	rseq: Kill process when unknown flags are encountered in ABI structures	2022-08-01 15:21:42 +02:00
scftorture.c	scftorture: Fix distribution of short handler delays	2022-04-11 17:07:29 -07:00
scs.c	kasan, vmalloc: only tag normal vmalloc allocations	2022-03-24 19:06:48 -07:00
seccomp.c	seccomp: Add wait_killable semantic to seccomp user notifier	2022-05-03 14:11:58 -07:00
signal.c	signal handling: don't use BUG_ON() for debugging	2022-07-07 09:53:43 -07:00
smp.c	locking/csd_lock: Change csdlock_debug from early_param to __setup	2022-07-19 11:40:00 -07:00
smpboot.c	cpu/hotplug: Allow the CPU in CPU_UP_PREPARE state to be brought up again.	2022-04-12 14:13:01 +02:00
smpboot.h
softirq.c	context_tracking: Take IRQ eqs entrypoints over RCU	2022-07-05 13:32:59 -07:00
stackleak.c	stackleak: add on/off stack variants	2022-05-08 01:33:09 -07:00
stacktrace.c	uaccess: remove CONFIG_SET_FS	2022-02-25 09:36:06 +01:00
static_call_inline.c	static_call: Don't make __static_call_return0 static	2022-04-05 09:59:38 +02:00
static_call.c	static_call: Don't make __static_call_return0 static	2022-04-05 09:59:38 +02:00
stop_machine.c	Scheduler changes in this cycle were:	2022-05-24 11:11:13 -07:00
sys_ni.c	mm/mempolicy: wire up syscall set_mempolicy_home_node	2022-01-15 16:30:30 +02:00
sys.c	arm64/sme: Implement vector length configuration prctl()s	2022-04-22 18:50:54 +01:00
sysctl-test.c
sysctl.c	Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net	2022-07-21 13:03:39 -07:00
task_work.c	task_work: allow TWA_SIGNAL without a rescheduling IPI	2022-04-30 08:39:32 -06:00
taskstats.c	kernel: make taskstats available from all net namespaces	2022-04-29 14:38:03 -07:00
torture.c	torture: Wake up kthreads after storing task_struct pointer	2022-02-01 17:24:39 -08:00
tracepoint.c
tsacct.c	taskstats: version 12 with thread group and exe info	2022-04-29 14:38:03 -07:00
ucount.c	ucounts: Handle wrapping in is_ucounts_overlimit	2022-02-17 09:11:57 -06:00
uid16.c
uid16.h
umh.c	kthread: Don't allocate kthread_struct for init and umh	2022-05-06 14:49:44 -05:00
up.c
user_namespace.c	ucounts: Fix systemd LimitNPROC with private users regression	2022-02-25 10:40:14 -06:00
user-return-notifier.c
user.c
usermode_driver.c	blob_to_mnt(): kern_unmount() is needed to undo kern_mount()	2022-05-19 23:25:47 -04:00
utsname_sysctl.c
utsname.c
watch_queue.c	This was a moderately busy cycle for documentation, but nothing all that	2022-08-02 19:24:24 -07:00
watchdog_hld.c	Revert "printk: add functions to prefer direct printing"	2022-06-23 18:41:40 +02:00
watchdog.c	Merge branch 'rework/kthreads' into for-linus	2022-06-23 19:11:28 +02:00
workqueue_internal.h
workqueue.c	workqueue: Avoid a false warning in unbind_workers()	2022-07-29 07:49:02 -10:00