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Yonghong Song 2921c90d47 bpf: Fix a verifier failure with xor
bpf selftest test_progs/test_sk_assign failed with llvm 11 and llvm 12.
Compared to llvm 10, llvm 11 and 12 generates xor instruction which
is not handled properly in verifier. The following illustrates the
problem:

  16: (b4) w5 = 0
  17: ... R5_w=inv0 ...
  ...
  132: (a4) w5 ^= 1
  133: ... R5_w=inv(id=0,umax_value=4294967295,var_off=(0x0; 0xffffffff)) ...
  ...
  37: (bc) w8 = w5
  38: ... R5=inv(id=0,umax_value=4294967295,var_off=(0x0; 0xffffffff))
          R8_w=inv(id=0,umax_value=4294967295,var_off=(0x0; 0xffffffff)) ...
  ...
  41: (bc) w3 = w8
  42: ... R3_w=inv(id=0,umax_value=4294967295,var_off=(0x0; 0xffffffff)) ...
  45: (56) if w3 != 0x0 goto pc+1
   ... R3_w=inv0 ...
  46: (b7) r1 = 34
  47: R1_w=inv34 R7=pkt(id=0,off=26,r=38,imm=0)
  47: (0f) r7 += r1
  48: R1_w=invP34 R3_w=inv0 R7_w=pkt(id=0,off=60,r=38,imm=0)
  48: (b4) w9 = 0
  49: R1_w=invP34 R3_w=inv0 R7_w=pkt(id=0,off=60,r=38,imm=0)
  49: (69) r1 = *(u16 *)(r7 +0)
  invalid access to packet, off=60 size=2, R7(id=0,off=60,r=38)
  R7 offset is outside of the packet

At above insn 132, w5 = 0, but after w5 ^= 1, we give a really conservative
value of w5. At insn 45, in reality the condition should be always false.
But due to conservative value for w3, the verifier evaluates it could be
true and this later leads to verifier failure complaining potential
packet out-of-bound access.

This patch implemented proper XOR support in verifier.
In the above example, we have:
  132: R5=invP0
  132: (a4) w5 ^= 1
  133: R5_w=invP1
  ...
  37: (bc) w8 = w5
  ...
  41: (bc) w3 = w8
  42: R3_w=invP1
  ...
  45: (56) if w3 != 0x0 goto pc+1
  47: R3_w=invP1
  ...
  processed 353 insns ...
and the verifier can verify the program successfully.

Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20200825064608.2017937-1-yhs@fb.com
2020-08-26 21:47:32 -07:00
..
bpf bpf: Fix a verifier failure with xor 2020-08-26 21:47:32 -07:00
cgroup for-5.9/block-20200802 2020-08-03 11:57:03 -07:00
configs compiler: remove CONFIG_OPTIMIZE_INLINING entirely 2020-04-07 10:43:42 -07:00
debug Remove uninitialized_var() macro for v5.9-rc1 2020-08-04 13:49:43 -07:00
dma Cleanup, SECCOMP_FILTER support, message printing fixes, and other 2020-08-15 18:50:32 -07:00
entry entry: Correct 'noinstr' attributes 2020-07-26 15:42:20 +02:00
events Misc fixes, an expansion of perf syscall access to CAP_PERFMON privileged tools, 2020-08-15 10:34:24 -07:00
gcov treewide: replace '---help---' in Kconfig files with 'help' 2020-06-14 01:57:21 +09:00
irq genirq: Unlock irq descriptor after errors 2020-08-13 09:35:59 +02:00
kcsan Merge branch 'kcsan' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu into locking/core 2020-08-01 09:26:27 +02:00
livepatch livepatch: Make klp_apply_object_relocs static 2020-05-11 00:31:38 +02:00
locking A set of locking fixes and updates: 2020-08-10 19:07:44 -07:00
power libnvdimm for 5.9 2020-08-11 10:59:19 -07:00
printk Printk changes for 5.9 2020-08-04 22:22:25 -07:00
rcu rcu: kasan: record and print call_rcu() call stack 2020-08-07 11:33:28 -07:00
sched Two fixes: fix a new tracepoint's output value, and fix the formatting of show-state syslog printouts. 2020-08-15 10:36:40 -07:00
time A set oftimekeeping/VDSO updates: 2020-08-14 14:26:08 -07:00
trace bpf: Add d_path helper 2020-08-25 15:41:15 -07:00
.gitignore .gitignore: add SPDX License Identifier 2020-03-25 11:50:48 +01:00
Kconfig.freezer
Kconfig.hz
Kconfig.locks sched/rt, locking: Use CONFIG_PREEMPTION 2019-12-08 14:37:36 +01:00
Kconfig.preempt sched/Kconfig: Fix spelling mistake in user-visible help text 2019-11-12 11:35:32 +01:00
Makefile bpf: Add kernel module with user mode driver that populates bpffs. 2020-08-20 16:02:36 +02:00
acct.c mmap locking API: convert mmap_sem comments 2020-06-09 09:39:14 -07:00
async.c treewide: Remove uninitialized_var() usage 2020-07-16 12:35:15 -07:00
audit.c audit/stable-5.9 PR 20200803 2020-08-04 14:20:26 -07:00
audit.h revert: 1320a4052e ("audit: trigger accompanying records when no rules present") 2020-07-29 10:00:36 -04:00
audit_fsnotify.c fsnotify: create method handle_inode_event() in fsnotify_operations 2020-07-27 23:25:50 +02:00
audit_tree.c \n 2020-08-06 19:29:51 -07:00
audit_watch.c fsnotify: create method handle_inode_event() in fsnotify_operations 2020-07-27 23:25:50 +02:00
auditfilter.c audit: fix a net reference leak in audit_list_rules_send() 2020-04-22 15:23:10 -04:00
auditsc.c audit/stable-5.9 PR 20200803 2020-08-04 14:20:26 -07:00
backtracetest.c treewide: Replace DECLARE_TASKLET() with DECLARE_TASKLET_OLD() 2020-07-30 11:15:58 -07:00
bounds.c
capability.c
compat.c uaccess: Selectively open read or write user access 2020-05-01 12:35:21 +10:00
configs.c proc: convert everything to "struct proc_ops" 2020-02-04 03:05:26 +00:00
context_tracking.c context_tracking: Ensure that the critical path cannot be instrumented 2020-06-11 15:14:36 +02:00
cpu.c The changes in this cycle are: 2020-06-03 13:06:42 -07:00
cpu_pm.c kernel/cpu_pm: Fix uninitted local in cpu_pm 2020-05-15 11:44:34 -07:00
crash_core.c kdump: append kernel build-id string to VMCOREINFO 2020-08-12 10:58:01 -07:00
crash_dump.c crash_dump: Remove no longer used saved_max_pfn 2020-04-15 11:21:54 +02:00
cred.c exec: Teach prepare_exec_creds how exec treats uids & gids 2020-05-20 14:44:21 -05:00
delayacct.c
dma.c
elfcore.c
exec_domain.c
exit.c kernel: add a kernel_wait helper 2020-08-12 10:57:59 -07:00
extable.c kernel/extable.c: use address-of operator on section symbols 2020-04-07 10:43:42 -07:00
fail_function.c
fork.c A set of locking fixes and updates: 2020-08-10 19:07:44 -07:00
freezer.c
futex.c futex: Convert to use the preferred 'fallthrough' macro 2020-08-13 21:02:12 +02:00
gen_kheaders.sh kbuild: add variables for compression tools 2020-06-06 23:42:01 +09:00
groups.c mm: remove the pgprot argument to __vmalloc 2020-06-02 10:59:11 -07:00
hung_task.c kernel/hung_task.c: introduce sysctl to print all traces when a hung task is detected 2020-06-08 11:05:56 -07:00
iomem.c
irq_work.c irq_work, smp: Allow irq_work on call_single_queue 2020-05-28 10:54:15 +02:00
jump_label.c
kallsyms.c Linux 5.8-rc7 2020-07-28 13:18:01 +02:00
kcmp.c kernel/kcmp.c: Use new infrastructure to fix deadlocks in execve 2020-03-25 10:04:01 -05:00
kcov.c kcov: make some symbols static 2020-08-12 10:58:02 -07:00
kexec.c kexec: add machine_kexec_post_load() 2020-01-08 16:32:55 +00:00
kexec_core.c kexec: add machine_kexec_post_load() 2020-01-08 16:32:55 +00:00
kexec_elf.c
kexec_file.c Misc fixes and small updates all around the place: 2020-08-15 10:38:03 -07:00
kexec_internal.h kexec: add machine_kexec_post_load() 2020-01-08 16:32:55 +00:00
kheaders.c
kmod.c kmod: remove redundant "be an" in the comment 2020-08-12 10:58:01 -07:00
kprobes.c Tracing updates for 5.9 2020-08-07 18:29:15 -07:00
ksysfs.c
kthread.c uaccess: add force_uaccess_{begin,end} helpers 2020-08-12 10:57:59 -07:00
latencytop.c sysctl: pass kernel pointers to ->proc_handler 2020-04-27 02:07:40 -04:00
module-internal.h
module.c Modules updates for v5.9 2020-08-14 11:07:02 -07:00
module_signature.c
module_signing.c
notifier.c mm: remove vmalloc_sync_(un)mappings() 2020-06-02 10:59:12 -07:00
nsproxy.c nsproxy: support CLONE_NEWTIME with setns() 2020-07-08 11:14:22 +02:00
padata.c padata: remove padata_parallel_queue 2020-07-23 17:34:18 +10:00
panic.c panic: make print_oops_end_marker() static 2020-08-12 10:58:02 -07:00
params.c
pid.c cap-checkpoint-restore-v5.9 2020-08-04 15:02:07 -07:00
pid_namespace.c pid_namespace: use checkpoint_restore_ns_capable() for ns_last_pid 2020-07-19 20:14:42 +02:00
profile.c proc: convert everything to "struct proc_ops" 2020-02-04 03:05:26 +00:00
ptrace.c ptrace: reintroduce usage of subjective credentials in ptrace_has_cap() 2020-01-18 13:51:39 +01:00
range.c
reboot.c arch: remove unicore32 port 2020-07-01 12:09:13 +03:00
regset.c regset: kill ->get() 2020-07-27 14:31:12 -04:00
relay.c mmap locking API: convert mmap_sem comments 2020-06-09 09:39:14 -07:00
resource.c /dev/mem: Revoke mappings when a driver claims the region 2020-05-27 11:10:05 +02:00
rseq.c rseq: Reject unknown flags on rseq unregister 2019-12-25 10:41:20 +01:00
scs.c mm: memcontrol: account kernel stack per node 2020-08-07 11:33:25 -07:00
seccomp.c seccomp: Introduce addfd ioctl to seccomp user notifier 2020-07-14 16:29:42 -07:00
signal.c task_work: only grab task signal lock when needed 2020-08-13 09:01:38 -06:00
smp.c smp: Fix a potential usage of stale nr_cpus 2020-07-22 10:22:04 +02:00
smpboot.c
smpboot.h
softirq.c tasklets API update for v5.9-rc1 2020-08-04 13:40:35 -07:00
stackleak.c gcc-plugins/stackleak: Use asm instrumentation to avoid useless register saving 2020-06-24 07:48:28 -07:00
stacktrace.c uaccess: add force_uaccess_{begin,end} helpers 2020-08-12 10:57:59 -07:00
stop_machine.c stop_machine: Make stop_cpus() static 2020-01-17 10:19:21 +01:00
sys.c prctl: exe link permission error changed from -EINVAL to -EPERM 2020-07-19 20:14:42 +02:00
sys_ni.c all arch: remove system call sys_sysctl 2020-08-14 19:56:56 -07:00
sysctl-test.c kunit: allow kunit tests to be loaded as a module 2020-01-09 16:42:29 -07:00
sysctl.c mm: use unsigned types for fragmentation score 2020-08-12 10:57:56 -07:00
task_work.c task_work: only grab task signal lock when needed 2020-08-13 09:01:38 -06:00
taskstats.c taskstats: fix data-race 2019-12-04 15:18:39 +01:00
test_kprobes.c
torture.c torture: Dump ftrace at shutdown only if requested 2020-06-29 12:01:45 -07:00
tracepoint.c
tsacct.c tsacct: add 64-bit btime field 2019-12-18 18:07:31 +01:00
ucount.c ucount: Make sure ucounts in /proc/sys/user don't regress again 2020-04-07 21:51:27 +02:00
uid16.c
uid16.h
umh.c kernel: add a kernel_wait helper 2020-08-12 10:57:59 -07:00
up.c smp/up: Make smp_call_function_single() match SMP semantics 2020-02-07 15:34:12 +01:00
user-return-notifier.c
user.c user.c: make uidhash_table static 2020-06-04 19:06:24 -07:00
user_namespace.c nsproxy: add struct nsset 2020-05-09 13:57:12 +02:00
usermode_driver.c umd: Stop using split_argv 2020-07-07 11:58:59 -05:00
utsname.c nsproxy: add struct nsset 2020-05-09 13:57:12 +02:00
utsname_sysctl.c sysctl: pass kernel pointers to ->proc_handler 2020-04-27 02:07:40 -04:00
watch_queue.c watch_queue: Limit the number of watches a user can hold 2020-08-17 09:39:18 -07:00
watchdog.c kernel/watchdog.c: convert {soft/hard}lockup boot parameters to sysctl aliases 2020-06-08 11:05:56 -07:00
watchdog_hld.c
workqueue.c maccess: rename probe_kernel_{read,write} to copy_{from,to}_kernel_nofault 2020-06-17 10:57:41 -07:00
workqueue_internal.h