WARNING in __mark_chain_precision (2)

* WARNING in __mark_chain_precision (2)
@ 2019-08-29 11:28 syzbot
  2019-09-01 18:23 ` syzbot
  2019-09-03  0:40 ` Alexei Starovoitov
  0 siblings, 2 replies; 3+ messages in thread
From: syzbot @ 2019-08-29 11:28 UTC (permalink / raw)
  To: ast, bpf, clang-built-linux, daniel, davem, hawk, jakub.kicinski,
	john.fastabend, kafai, linux-kernel, netdev, songliubraving,
	syzkaller-bugs, yhs

Hello,

syzbot found the following crash on:

HEAD commit:    47ee6e86 selftests/bpf: remove wrong nhoff in flow dissect..
git tree:       bpf-next
console output: https://syzkaller.appspot.com/x/log.txt?x=16227fa6600000
kernel config:  https://syzkaller.appspot.com/x/.config?x=d4cf1ffb87d590d7
dashboard link: https://syzkaller.appspot.com/bug?extid=c8d66267fd2b5955287e
compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=10d26ebc600000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=127805ca600000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+c8d66267fd2b5955287e@syzkaller.appspotmail.com

------------[ cut here ]------------
verifier backtracking bug
WARNING: CPU: 0 PID: 8795 at kernel/bpf/verifier.c:1782  
__mark_chain_precision+0x197a/0x1ea0 kernel/bpf/verifier.c:1782
Kernel panic - not syncing: panic_on_warn set ...
CPU: 0 PID: 8795 Comm: syz-executor439 Not tainted 5.3.0-rc3+ #101
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
Call Trace:
  __dump_stack lib/dump_stack.c:77 [inline]
  dump_stack+0x172/0x1f0 lib/dump_stack.c:113
  panic+0x2dc/0x755 kernel/panic.c:219
  __warn.cold+0x20/0x4c kernel/panic.c:576
  report_bug+0x263/0x2b0 lib/bug.c:186
  fixup_bug arch/x86/kernel/traps.c:179 [inline]
  fixup_bug arch/x86/kernel/traps.c:174 [inline]
  do_error_trap+0x11b/0x200 arch/x86/kernel/traps.c:272
  do_invalid_op+0x37/0x50 arch/x86/kernel/traps.c:291
  invalid_op+0x23/0x30 arch/x86/entry/entry_64.S:1028
RIP: 0010:__mark_chain_precision+0x197a/0x1ea0 kernel/bpf/verifier.c:1782
Code: 08 31 ff 89 de e8 a6 9e f2 ff 84 db 0f 85 07 ff ff ff e8 59 9d f2 ff  
48 c7 c7 a0 a7 91 87 c6 05 3d c6 21 08 01 e8 1e 10 c4 ff <0f> 0b 41 bc f2  
ff ff ff e9 e8 fe ff ff 48 8b bd d8 fe ff ff e8 cd
RSP: 0018:ffff88808609f380 EFLAGS: 00010286
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff815c3ba6 RDI: ffffed1010c13e62
RBP: ffff88808609f4d0 R08: ffff8880a97940c0 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000001
R13: ffff8880985b6cc0 R14: ffff88808e538e80 R15: ffff88808609f468
  mark_chain_precision kernel/bpf/verifier.c:1819 [inline]
  check_cond_jmp_op+0xcd8/0x3c30 kernel/bpf/verifier.c:5841
  do_check+0x63cd/0x8a30 kernel/bpf/verifier.c:7783
  bpf_check+0x6fff/0x99b2 kernel/bpf/verifier.c:9297
  bpf_prog_load+0xe68/0x1670 kernel/bpf/syscall.c:1709
  __do_sys_bpf+0xa44/0x3350 kernel/bpf/syscall.c:2860
  __se_sys_bpf kernel/bpf/syscall.c:2819 [inline]
  __x64_sys_bpf+0x73/0xb0 kernel/bpf/syscall.c:2819
  do_syscall_64+0xfd/0x6a0 arch/x86/entry/common.c:296
  entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x4402a9
Code: 18 89 d0 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 48 89 f8 48 89 f7  
48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff  
ff 0f 83 fb 13 fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007ffc52f10618 EFLAGS: 00000246 ORIG_RAX: 0000000000000141
RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 00000000004402a9
RDX: 0000000000000048 RSI: 0000000020000200 RDI: 0000000000000005
RBP: 00000000006ca018 R08: 0000000000000000 R09: 0000000000000000
R10: 00000000ffffffff R11: 0000000000000246 R12: 0000000000401b30
R13: 0000000000401bc0 R14: 0000000000000000 R15: 0000000000000000
Kernel Offset: disabled
Rebooting in 86400 seconds..

---
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