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Daniel Borkmann f70280ee89 bpf: Fix passing modified ctx to ld/abs/ind instruction 
commit 6d4f151acf9a4f6fab09b615f246c717ddedcf0c upstream.

Anatoly has been fuzzing with kBdysch harness and reported a KASAN
slab oob in one of the outcomes:

  [...]
  [   77.359642] BUG: KASAN: slab-out-of-bounds in bpf_skb_load_helper_8_no_cache+0x71/0x130
  [   77.360463] Read of size 4 at addr ffff8880679bac68 by task bpf/406
  [   77.361119]
  [   77.361289] CPU: 2 PID: 406 Comm: bpf Not tainted 5.5.0-rc2-xfstests-00157-g2187f215eba #1
  [   77.362134] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014
  [   77.362984] Call Trace:
  [   77.363249]  dump_stack+0x97/0xe0
  [   77.363603]  print_address_description.constprop.0+0x1d/0x220
  [   77.364251]  ? bpf_skb_load_helper_8_no_cache+0x71/0x130
  [   77.365030]  ? bpf_skb_load_helper_8_no_cache+0x71/0x130
  [   77.365860]  __kasan_report.cold+0x37/0x7b
  [   77.366365]  ? bpf_skb_load_helper_8_no_cache+0x71/0x130
  [   77.366940]  kasan_report+0xe/0x20
  [   77.367295]  bpf_skb_load_helper_8_no_cache+0x71/0x130
  [   77.367821]  ? bpf_skb_load_helper_8+0xf0/0xf0
  [   77.368278]  ? mark_lock+0xa3/0x9b0
  [   77.368641]  ? kvm_sched_clock_read+0x14/0x30
  [   77.369096]  ? sched_clock+0x5/0x10
  [   77.369460]  ? sched_clock_cpu+0x18/0x110
  [   77.369876]  ? bpf_skb_load_helper_8+0xf0/0xf0
  [   77.370330]  ___bpf_prog_run+0x16c0/0x28f0
  [   77.370755]  __bpf_prog_run32+0x83/0xc0
  [   77.371153]  ? __bpf_prog_run64+0xc0/0xc0
  [   77.371568]  ? match_held_lock+0x1b/0x230
  [   77.371984]  ? rcu_read_lock_held+0xa1/0xb0
  [   77.372416]  ? rcu_is_watching+0x34/0x50
  [   77.372826]  sk_filter_trim_cap+0x17c/0x4d0
  [   77.373259]  ? sock_kzfree_s+0x40/0x40
  [   77.373648]  ? __get_filter+0x150/0x150
  [   77.374059]  ? skb_copy_datagram_from_iter+0x80/0x280
  [   77.374581]  ? do_raw_spin_unlock+0xa5/0x140
  [   77.375025]  unix_dgram_sendmsg+0x33a/0xa70
  [   77.375459]  ? do_raw_spin_lock+0x1d0/0x1d0
  [   77.375893]  ? unix_peer_get+0xa0/0xa0
  [   77.376287]  ? __fget_light+0xa4/0xf0
  [   77.376670]  __sys_sendto+0x265/0x280
  [   77.377056]  ? __ia32_sys_getpeername+0x50/0x50
  [   77.377523]  ? lock_downgrade+0x350/0x350
  [   77.377940]  ? __sys_setsockopt+0x2a6/0x2c0
  [   77.378374]  ? sock_read_iter+0x240/0x240
  [   77.378789]  ? __sys_socketpair+0x22a/0x300
  [   77.379221]  ? __ia32_sys_socket+0x50/0x50
  [   77.379649]  ? mark_held_locks+0x1d/0x90
  [   77.380059]  ? trace_hardirqs_on_thunk+0x1a/0x1c
  [   77.380536]  __x64_sys_sendto+0x74/0x90
  [   77.380938]  do_syscall_64+0x68/0x2a0
  [   77.381324]  entry_SYSCALL_64_after_hwframe+0x49/0xbe
  [   77.381878] RIP: 0033:0x44c070
  [...]

After further debugging, turns out while in case of other helper functions
we disallow passing modified ctx, the special case of ld/abs/ind instruction
which has similar semantics (except r6 being the ctx argument) is missing
such check. Modified ctx is impossible here as bpf_skb_load_helper_8_no_cache()
and others are expecting skb fields in original position, hence, add
check_ctx_reg() to reject any modified ctx. Issue was first introduced back
in f1174f77b50c ("bpf/verifier: rework value tracking").

Fixes: f1174f77b50c ("bpf/verifier: rework value tracking")
Reported-by: Anatoly Trosinenko <anatoly.trosinenko@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200106215157.3553-1-daniel@iogearbox.net
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-01-12 12:17:04 +01:00
..
bpf
bpf: Fix passing modified ctx to ld/abs/ind instruction
2020-01-12 12:17:04 +01:00
cgroup
cgroup: pids: use atomic64_t for pids->limit
2019-12-17 20:34:56 +01:00
configs
kconfig: tinyconfig: remove stale stack protector fixups
2018-06-15 07:15:28 +09:00
debug
kdb: Don't back trace on a cpu that didn't round up
2019-02-12 19:47:19 +01:00
dma
dma-debug: add a schedule point in debug_dma_dump_mappings()
2020-01-04 19:12:43 +01:00
events
perf/core: Consistently fail fork on allocation failures
2019-12-13 08:51:04 +01:00
gcov
gcov: remove CONFIG_GCOV_FORMAT_AUTODETECT
2018-06-08 18:56:02 +09:00
irq
irq/matrix: Fix memory overallocation
2019-12-01 09:17:13 +01:00
livepatch
livepatch: Nullify obj->mod in klp_module_coming()'s error path
2019-10-07 18:57:10 +02:00
locking
Revert "locking/pvqspinlock: Don't wait if vCPU is preempted"
2019-10-11 18:21:06 +02:00
power
PM / hibernate: memory_bm_find_bit(): Tighten node optimisation
2020-01-09 10:18:58 +01:00
printk
printk: fix integer overflow in setup_log_buf()
2019-12-01 09:16:14 +01:00
rcu
rcuperf: Fix cleanup path for invalid perf_type strings
2019-05-31 06:46:30 -07:00
sched
cpufreq: Avoid leaving stale IRQ work items during CPU offline
2019-12-31 16:36:22 +01:00
time
ptp: fix the race between the release of ptp_clock and cdev
2020-01-04 19:13:35 +01:00
trace
ftrace: Avoid potential division by zero in function profiler
2020-01-09 10:19:03 +01:00
.gitignore
…
acct.c
acct_on(): don't mess with freeze protection
2019-05-31 06:46:05 -07:00
async.c
kernel/async.c: revert "async: simplify lowest_in_progress()"
2018-02-06 18:32:44 -08:00
audit_fsnotify.c
fsnotify: add fsnotify_add_inode_mark() wrappers
2018-05-18 14:58:22 +02:00
audit_tree.c
audit: Embed key into chunk
2019-12-13 08:51:11 +01:00
audit_watch.c
audit_get_nd(): don't unlock parent too early
2019-12-13 08:51:02 +01:00
audit.c
audit: use ktime_get_coarse_real_ts64() for timestamps
2018-07-17 14:45:08 -04:00
audit.h
audit: track the owner of the command mutex ourselves
2018-02-23 11:22:22 -05:00
auditfilter.c
audit: fix a memory leak bug
2019-05-31 06:46:17 -07:00
auditsc.c
audit: print empty EXECVE args
2019-12-01 09:17:17 +01:00
backtracetest.c
…
bounds.c
kbuild: fix kernel/bounds.c 'W=1' warning
2018-11-13 11:08:47 -08:00
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
time: Enable get/put_compat_itimerspec64 always
2018-06-24 14:39:47 +02:00
configs.c
…
context_tracking.c
…
cpu_pm.c
…
cpu.c
cpu/SMT: State SMT is disabled even with nosmt and without "=force"
2019-11-24 08:20:18 +01:00
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
memcg: account security cred as well to kmemcg
2020-01-09 10:19:00 +01:00
delayacct.c
delayacct: Use raw_spinlocks
2018-04-27 14:34:51 +02:00
dma.c
proc: introduce proc_create_single{,_data}
2018-05-16 07:23:35 +02:00
elfcore.c
kernel/elfcore.c: include proper prototypes
2019-10-11 18:21:23 +02:00
exec_domain.c
proc: introduce proc_create_single{,_data}
2018-05-16 07:23:35 +02:00
exit.c
exit: panic before exit_mm() on global init exit
2020-01-09 10:19:02 +01:00
extable.c
extable: Make init_kernel_text() global
2018-02-21 16:54:06 +01:00
fail_function.c
bpf/error-inject/kprobes: Clear current_kprobe and enable preempt in kprobe
2018-06-21 12:33:19 +02:00
fork.c
fork: fix some -Wmissing-prototypes warnings
2019-12-05 09:21:04 +01:00
freezer.c
PM / reboot: Eliminate race between reboot and suspend
2018-08-06 12:35:20 +02:00
futex.c
futex: Prevent robust futex exit race
2019-12-01 09:17:38 +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
kernel: hung_task.c: disable on suspend
2019-04-20 09:16:02 +02:00
iomem.c
memremap: split devm_memremap_pages() and memremap() infrastructure
2018-05-15 23:08:33 -07:00
irq_work.c
irq_work: Do not raise an IPI when queueing work on the local CPU
2019-05-31 06:46:19 -07:00
jump_label.c
jump_label: move 'asm goto' support test to Kconfig
2019-06-04 08:02:34 +02:00
kallsyms.c
kallsyms: Don't let kallsyms_lookup_size_offset() fail on retrieving the first symbol
2019-09-21 07:17:02 +02:00
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
kconfig: include kernel/Kconfig.preempt from init/Kconfig
2018-08-02 08:06:54 +09:00
kcov.c
kernel/kcov.c: mark write_comp_data() as notrace
2019-02-12 19:47:20 +01:00
kexec_core.c
kexec: Allocate decrypted control pages for kdump if SME is enabled
2019-11-24 08:20:29 +01:00
kexec_file.c
treewide: Use array_size() in vzalloc()
2018-06-12 16:19:22 -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
kexec.c
kexec: add call to LSM hook in original kexec_load syscall
2018-07-16 12:31:57 -07:00
kmod.c
…
kprobes.c
kprobes: Blacklist symbols in arch-defined prohibited area
2019-12-05 09:20:26 +01:00
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
y2038: futex: Move compat implementation into futex.c
2019-12-01 09:17:38 +01:00
memremap.c
mm, devm_memremap_pages: add MEMORY_DEVICE_PRIVATE support
2019-01-13 09:51:04 +01:00
module_signing.c
modsign: log module name in the event of an error
2018-07-02 11:36:17 +02:00
module-internal.h
modsign: log module name in the event of an error
2018-07-02 11:36:17 +02:00
module.c
kernel/module.c: wakeup processes in module_wq on module unload
2019-12-17 20:35:57 +01:00
notifier.c
…
nsproxy.c
…
padata.c
padata: use smp_mb in padata_reorder to avoid orphaned padata jobs
2019-07-26 09:14:25 +02:00
panic.c
kernel/panic.c: do not append newline to the stack protector panic string
2019-12-01 09:17:10 +01:00
params.c
kernel/params.c: downgrade warning for unsafe parameters
2018-04-11 10:28:37 -07:00
pid_namespace.c
signal/pid_namespace: Fix reboot_pid_ns to use send_sig not force_sig
2019-07-26 09:14:01 +02:00
pid.c
Fix failure path in alloc_pid()
2019-01-13 09:51:06 +01:00
profile.c
…
ptrace.c
ptrace: Fix ->ptracer_cred handling for PTRACE_TRACEME
2019-07-10 09:53:41 +02:00
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
PM / reboot: Eliminate race between reboot and suspend
2018-08-06 12:35:20 +02:00
relay.c
relay: check return of create_buf_file() properly
2019-03-13 14:02:35 -07:00
resource.c
resource: fix locking in find_next_iomem_res()
2019-09-16 08:22:20 +02:00
rseq.c
rseq: uapi: Declare rseq_cs field as union, update includes
2018-07-10 22:18:52 +02:00
seccomp.c
audit/stable-4.18 PR 20180605
2018-06-06 16:34:00 -07:00
signal.c
signal: Always ignore SIGKILL and SIGSTOP sent to the global init
2019-11-20 18:46:21 +01:00
smp.c
cpu/hotplug: Fix "SMT disabled by BIOS" detection for KVM
2019-02-12 19:47:25 +01:00
smpboot.c
smpboot: Remove cpumask from the API
2018-07-03 09:20:44 +02:00
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
nohz: Fix missing tick reprogram when interrupting an inline softirq
2018-08-03 15:52:10 +02:00
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_ni.c
Merge branch 'core-rseq-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
2018-06-10 10:17:09 -07:00
sys.c
kernel/sys.c: prctl: fix false positive in validate_prctl_map()
2019-06-15 11:54:01 +02:00
sysctl_binary.c
staging: irda: remove remaining remants of irda code removal
2018-04-16 11:26:49 +02:00
sysctl.c
kernel: sysctl: make drop_caches write-only
2020-01-04 19:13:17 +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
taskstats: fix data-race
2020-01-09 10:18:59 +01:00
test_kprobes.c
kprobes: Remove jprobe API implementation
2018-06-21 12:33:05 +02:00
torture.c
torture: Keep old-school dmesg format
2018-06-25 11:30:10 -07:00
tracepoint.c
tracepoint: Fix tracepoint array element size mismatch
2018-10-17 15:35:29 -04:00
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
umh: fix race condition
2018-06-07 16:56:28 -04:00
up.c
…
user_namespace.c
userns: also map extents in the reverse map to kernel IDs
2018-11-13 11:09:00 -08:00
user-return-notifier.c
…
user.c
userns: use irqsave variant of refcount_dec_and_lock()
2018-08-22 10:52:47 -07:00
utsname_sysctl.c
sys: don't hold uts_sem while accessing userspace memory
2018-08-11 02:05:53 -05:00
utsname.c
uts: create "struct uts_namespace" from kmem_cache
2018-04-11 10:28:35 -07:00
watchdog_hld.c
watchdog: Mark watchdog touch functions as notrace
2018-08-30 12:56:40 +02:00
watchdog.c
watchdog: Respect watchdog cpumask on CPU hotplug
2019-04-03 06:26:29 +02:00
workqueue_internal.h
workqueue: Set worker->desc to workqueue name by default
2018-05-18 08:47:13 -07:00
workqueue.c
workqueue: Fix missing kfree(rescuer) in destroy_workqueue()
2019-12-17 20:35:50 +01:00