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cdeea29719
linux/kernel
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Kumar Kartikeya Dwivedi 8901cee931
bpf: Compare stack frames in regs_exact() 
regs_exact() compares the register state up to id, followed by the ID
mappings, but does not compare frameno. The PTR_TO_STACK case in regsafe()
checks frameno separately, which is bypassed when exact comparison is
requested. Consequently, infinite-loop detection can treat pointers to
different stack frames as the same pointer and reject a finite loop.

For example, initialize fp-8 to zero in the caller and to one in the
callee, then pass the caller's fp-8 to the callee as r1:

    loop:
        r0 = *(u64 *)(r1 + 0);
        if r0 != 0 goto done;
        r1 = r10;
        r1 += -8;
        goto loop;
    done:
        exit;

The loop terminates after reading the callee's slot on its second
iteration. At the loop header, however, the only relevant difference is
r1's frameno, so exact comparison incorrectly reports an infinite loop.
The same problem occurs when the pointer is spilled to the stack.

Move frameno into the type-specific metadata union, ahead of id, so the
existing prefix comparison in regs_exact() covers it. Ordinary stack
pointers do not use another union member. Iterator and IRQ stack-slot
states use their dedicated union views and do not need a frame lookup.
This also keeps bpf_reg_state at 80 bytes.

Since frameno now shares storage with other pointer metadata, it is only
meaningful for PTR_TO_STACK registers. Return NULL from bpf_func() for
other register types. process_iter_arg(), get_constant_map_key() and
is_dynptr_reg_valid_init() look up the frame before checking the register
type and would otherwise index frame[] with a byte of the register's map
or BTF pointer. They dereference the frame only after their type check.

Move the states_maybe_looping() boundary from frameno to precise after the
field relocation. Its prefix comparison continues to cover the complete
value state and now includes frameno.

Continue to ignore precise. Precision marks control whether pruning may
ignore scalar ranges; they do not change the represented values, and exact
comparison already compares those ranges unconditionally. Marks can also
change through backtracking while an ancestor state is still being
explored.

Fixes: d5b892fd60 ("bpf: make infinite loop detection in is_state_visited() exact")
Reported-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://patch.msgid.link/20260919014213.1840880-2-memxor@gmail.com
2026-09-19 05:25:14 +00:00
..
bpf bpf: Compare stack frames in regs_exact() 2026-09-19 05:25:14 +00:00
cgroup cgroup: Fixes for v7.3-rc1 2026-08-31 14:20:32 -07:00
configs slab: support for compiler-assisted type-based slab cache partitioning 2026-05-14 10:44:09 +02:00
debug kgdb: update outdated references to kgdb_wait() 2026-04-21 16:41:54 +01:00
dma treewide: refresh kmalloc_obj() conversions 2026-09-04 21:37:00 -07:00
entry entry: Rework trace_syscall_enter() 2026-07-20 20:38:40 +02:00
events Misc perf events fixes: 2026-09-06 11:06:09 -07:00
futex Misc locking fixes: 2026-09-06 10:45:46 -07:00
gcov Convert more 'alloc_obj' cases to default GFP_KERNEL arguments 2026-02-21 20:03:00 -08:00
irq treewide: refresh kmalloc_obj() conversions 2026-09-04 21:37:00 -07:00
kcsan kcsan: avoid unintended access checking in NMIs 2026-07-20 18:18:37 +02:00
livepatch livepatch: Fix NULL pointer dereference in klp_find_func() 2026-07-07 12:54:37 +02:00
liveupdate kho: make boot time huge page allocation work nicely with KHO 2026-08-23 09:17:38 -07:00
locking Misc locking fixes: 2026-09-06 10:45:46 -07:00
module module: validate string table section types 2026-08-06 16:44:45 +02:00
power PM: sleep: Allow disabling DPM watchdog by default 2026-07-23 15:46:34 +02:00
printk Merge branch 'for-7.3-console-registration-cleanup' into for-linus 2026-08-19 10:00:46 +02:00
rcu RCU updates: 2026-08-23 18:00:22 -07:00
sched Miscellaneous scheduler fixes: 2026-09-06 11:08:44 -07:00
time s390 updates for 7.3 merge window 2026-08-23 10:26:44 -07:00
trace tracing fixes for v7.3: 2026-09-06 14:21:24 -07:00
unwind Convert more 'alloc_obj' cases to default GFP_KERNEL arguments 2026-02-21 20:03:00 -08:00
.gitignore kheaders: rebuild kheaders_data.tar.xz when a file is modified within a minute 2025-06-24 20:30:37 +09:00
acct.c fs: move SB_I_USERNS_VISIBLE to FS_USERNS_MOUNT_RESTRICTED 2026-05-11 23:13:01 +02:00
async.c Convert 'alloc_obj' family to use the new default GFP_KERNEL argument 2026-02-21 17:09:51 -08:00
audit_fsnotify.c audit: fix recursive locking deadlock in audit_dupe_exe() 2026-05-27 19:15:34 -04:00
audit_tree.c audit: use 'unsigned int' instead of 'unsigned' 2026-05-26 17:15:30 -04:00
audit_watch.c audit: drop BUG_ON() from audit_add_to_parent() 2026-07-28 15:53:48 -04:00
audit.c audit: fix potential integer overflow in audit_log_n_string() 2026-07-29 16:19:06 -04:00
audit.h audit: fix recursive locking deadlock in audit_dupe_exe() 2026-05-27 19:15:34 -04:00
auditfilter.c audit/stable-7.3 PR 20260814 2026-08-19 16:21:32 -07:00
auditsc.c audit: drop BUG_ON() from audit_signal_info_syscall() 2026-07-28 15:53:49 -04:00
backtracetest.c
bounds.c x86/asm: Remove ANNOTATE_DATA_SPECIAL usage 2025-12-03 16:53:19 +01:00
capability.c capability: unexport has_capability_noaudit 2026-08-21 09:09:55 +02:00
cfi.c cfi: Move BPF CFI types and helpers to generic code 2025-07-31 18:23:53 -07:00
compat.c
configs.c
context_tracking.c context_tracking: Remove rcu_task_trace_heavyweight_{enter,exit}() 2026-01-01 16:39:46 +08:00
cpu_pm.c syscore: Pass context data to callbacks 2025-11-14 10:01:52 +01:00
cpu.c Misc CPU hotplug fixes: 2026-06-23 16:43:24 -07:00
crash_core_test.c crash: add KUnit tests for crash_exclude_mem_range 2025-09-13 17:32:55 -07:00
crash_core.c powerpc/kexec_file: Use crash_exclude_core_ranges() helper 2026-06-30 18:49:06 +03:00
crash_dump_dm_crypt.c crash_dump: release keyring reference at the correct time 2026-07-13 10:04:47 +03:00
crash_reserve.c kernel/crash: remove inclusion of crypto/sha1.h 2026-03-27 21:19:46 -07:00
cred.c exec_state: relocate dumpable information 2026-05-26 11:02:01 +02:00
delayacct.c sysctl: remove CONFIG_PROC_SYSCTL, it just mirrors CONFIG_SYSCTL 2026-08-05 15:28:23 +02:00
dma.c
elfcorehdr.c
exec_domain.c
exec_state.c exec_state: relocate dumpable information 2026-05-26 11:02:01 +02:00
exit.c Miscellaneous futex fixes: 2026-08-22 16:29:20 -07:00
exit.h
extable.c
fail_function.c Convert 'alloc_obj' family to use the new default GFP_KERNEL argument 2026-02-21 17:09:51 -08:00
fork.c mm.git review status for master..mm-nonmm-stable 2026-08-23 08:07:11 -07:00
freezer.c freezer: Clarify that only cgroup1 freezer uses PM freezer 2025-10-30 20:10:27 +01:00
gen_kheaders.sh kheaders: make it possible to override TAR 2025-08-06 10:23:36 +09:00
groups.c treewide: Replace kmalloc with kmalloc_obj for non-scalar types 2026-02-21 01:02:28 -08:00
hung_task.c hung_task: explicitly report I/O wait state in log output 2026-03-27 21:19:40 -07:00
iomem.c
irq_work.c irq_work: Fix use-after-free in irq_work_single() on PREEMPT_RT 2026-05-11 16:28:04 +02:00
jump_label.c treewide: refresh kmalloc_obj() conversions 2026-09-04 21:37:00 -07:00
kallsyms_internal.h kallsyms: Get rid of kallsyms relative base 2026-01-22 15:58:22 -07:00
kallsyms_selftest.c Convert 'alloc_obj' family to use the new default GFP_KERNEL argument 2026-02-21 17:09:51 -08:00
kallsyms_selftest.h
kallsyms.c mm.git review status for linus..mm-nonmm-stable 2026-02-12 12:13:01 -08:00
kcmp.c fs: add real_fs to track task's actual fs_struct 2026-06-29 10:43:45 +02:00
Kconfig.freezer
Kconfig.hz
Kconfig.kexec liveupdate: kho: move to kernel/liveupdate 2025-11-27 14:24:33 -08:00
Kconfig.locks locking/qspinlock: Add contended_release tracepoint 2026-08-07 17:58:10 +02:00
Kconfig.preempt sched_ext: Changes for v7.3 2026-08-20 11:01:37 -07:00
kcov.c mm.git review status for master..mm-nonmm-stable 2026-08-23 08:07:11 -07:00
kexec_core.c liveupdate: skip serialization for context-preserving kexec 2026-06-01 09:19:38 +03:00
kexec_elf.c
kexec_file.c kexec_file: skip checksum verification when safe 2026-07-01 13:01:08 +03:00
kexec_internal.h kexec: enable CMA based contiguous allocation 2025-08-02 12:01:38 -07:00
kexec.c Convert 'alloc_obj' family to use the new default GFP_KERNEL argument 2026-02-21 17:09:51 -08:00
kheaders.c
kprobes.c kprobes: Protect kprobe_blacklist with RCU 2026-09-03 09:04:25 +09:00
kstack_erase.c sysctl: remove __user qualifier from stack_erasing_sysctl buffer argument 2025-11-27 15:44:53 +01:00
ksyms_common.c
ksysfs.c kernel: ksysfs: initialize kernel_kobj earlier 2026-04-03 19:39:52 +02:00
kthread.c treewide: refresh kmalloc_obj() conversions 2026-09-04 21:37:00 -07:00
latencytop.c
Makefile exec: introduce struct task_exec_state 2026-05-26 11:02:01 +02:00
module_signature.c module: Give 'enum pkey_id_type' a more specific name 2026-03-24 21:42:37 +00:00
notifier.c
nscommon.c nsfs: tighten permission checks for ns iteration ioctls 2026-02-27 22:00:08 +01:00
nsproxy.c vfs-7.1-rc1.mount.v2 2026-04-14 19:59:25 -07:00
nstree.c nstree: tighten permission checks for listing 2026-02-27 22:00:11 +01:00
padata.c padata: Put CPU offline callback in ONLINE section to allow failure 2026-03-22 11:17:59 +09:00
panic.c bug/kunit: Core support for suppressing warning backtraces 2026-05-14 10:50:00 -06:00
params.c mm.git review status for master..mm-nonmm-stable 2026-08-23 08:07:11 -07:00
pid_namespace.c pid_namespace: allow opening pid_for_children before init was created 2026-03-20 14:44:26 +01:00
pid_sysctl.h
pid.c Summary 2026-08-20 08:46:41 -07:00
profile.c
ptrace.c exec_state: relocate dumpable information 2026-05-26 11:02:01 +02:00
range.c
reboot.c sysctl: move the "cad_pid" entry from pid_table[] to kern_reboot_table[] 2026-08-05 15:28:23 +02:00
regset.c
relay.c Convert 'alloc_obj' family to use the new default GFP_KERNEL argument 2026-02-21 17:09:51 -08:00
resource_kunit.c Convert 'alloc_obj' family to use the new default GFP_KERNEL argument 2026-02-21 17:09:51 -08:00
resource.c resource: downgrade "resource sanity check" warning to debug level 2026-08-03 21:10:05 -07:00
rseq.c rseq: Reenable performance optimizations conditionally 2026-05-06 17:40:27 +02:00
scftorture.c smp_call_function() torture-test updates: 2026-08-23 19:28:04 -07:00
scs.c scs: fix a wrong parameter in __scs_magic 2025-11-12 10:00:13 -08:00
seccomp.c seccomp, treewide: Rename and convert __secure_computing() to return boolean 2026-07-12 12:38:02 +02:00
signal.c signal: factor out the kernel reserved si_code check 2026-08-13 15:42:08 -07:00
smp.c SMP core updates: 2026-08-18 15:29:53 -07:00
smpboot.c sched/smp: Use the SMP version of idle_thread_set_boot_cpu() 2025-06-13 08:47:20 +02:00
smpboot.h
softirq.c interrupt: Disable interrupt before modifying hardirq_disable counter 2026-08-30 08:39:04 +02:00
stacktrace.c
static_call_inline.c Convert 'alloc_obj' family to use the new default GFP_KERNEL argument 2026-02-21 17:09:51 -08:00
static_call.c
stop_machine.c stop_machine: Make stop_one_cpu_nowait() return void 2026-07-31 12:35:26 +02:00
sys_ni.c time: Respect COMPAT_32BIT_TIME for old time type functions 2026-07-07 23:52:53 +02:00
sys.c prctl: fix PR_SET_MM_AUXV losing the forced AT_NULL terminator 2026-08-19 19:55:05 -07:00
sysctl-test.c
sysctl.c sysctl: remove CONFIG_PROC_SYSCTL, it just mirrors CONFIG_SYSCTL 2026-08-05 15:28:23 +02:00
task_work.c task_work: Fix NMI race condition 2025-10-29 10:29:54 +01:00
taskstats.c taskstats: fold the two cpumask handlers into one 2026-08-13 15:42:05 -07:00
torture.c torture: Don't leak shuffle_tmp_mask when shuffler kthread fails to start 2026-08-14 14:59:21 -07:00
tracepoint.c tracepoint: balance regfunc() on func_add() failure in tracepoint_add_func() 2026-04-14 05:17:02 -04:00
tsacct.c tsacct: skip all kernel threads 2026-01-26 19:07:13 -08:00
ucount.c binfmt_misc: correctly account pre-opened interpreters 2026-08-03 23:36:18 +02:00
uid16.c
uid16.h
umh.c fs: add umh argument to struct kernel_clone_args 2026-06-29 10:54:41 +02:00
up.c smp: Refactor remote CPU selection in smp_call_function_any() 2026-07-16 09:24:55 +02:00
user_namespace.c Convert remaining multi-line kmalloc_obj/flex GFP_KERNEL uses 2026-02-22 08:26:33 -08:00
user-return-notifier.c
user.c binfmt_misc: use RCU for the handler lookup 2026-08-03 10:08:36 +02:00
utsname_sysctl.c sysctl: remove CONFIG_PROC_SYSCTL, it just mirrors CONFIG_SYSCTL 2026-08-05 15:28:23 +02:00
utsname.c namespace-6.18-rc1 2025-09-29 11:20:29 -07:00
vhost_task.c vhost_task_create: kill unnecessary .exit_signal initialization 2026-06-10 02:17:00 -04:00
vmcore_info.c mm.git review status for linus..mm-nonmm-stable 2026-04-16 20:11:56 -07:00
watch_queue.c Convert 'alloc_flex' family to use the new default GFP_KERNEL argument 2026-02-21 17:09:51 -08:00
watchdog_buddy.c watchdog/hardlockup: improve buddy system detection timeliness 2026-03-27 21:19:47 -07:00
watchdog_perf.c watchdog/hardlockup: simplify perf event probe and remove per-cpu dependency 2026-02-08 00:13:35 -08:00
watchdog.c watchdog/softlockup: fix softlockup typos 2026-08-03 21:10:06 -07:00
workqueue_internal.h workqueue: Show in-flight work item duration in stall diagnostics 2026-03-05 07:27:48 -10:00
workqueue.c workqueue: Fixes for v7.3-rc1 2026-08-31 14:38:40 -07:00