syzbot


general protection fault in btf_decl_tag_resolve

Status: upstream: reported C repro on 2022/02/03 03:36
Reported-by: syzbot+53619be9444215e785ed@syzkaller.appspotmail.com
Fix commit: d7e7b42f4f95 bpf: Fix a btf decl_tag bug when tagging a function
Patched on: [ci-qemu-upstream ci-qemu-upstream-386 ci-qemu2-arm32 ci-qemu2-arm64 ci-qemu2-arm64-compat ci-qemu2-arm64-mte ci-upstream-bpf-kasan-gce ci-upstream-bpf-next-kasan-gce ci-upstream-gce-leak ci-upstream-kasan-gce ci-upstream-kasan-gce-386 ci-upstream-kasan-gce-root ci-upstream-kasan-gce-selinux-root ci-upstream-kasan-gce-smack-root ci-upstream-kmsan-gce ci-upstream-kmsan-gce-386 ci-upstream-linux-next-kasan-gce-root ci-upstream-net-kasan-gce ci-upstream-net-this-kasan-gce ci2-upstream-kcsan-gce ci2-upstream-usb], missing on: [ci-qemu2-riscv64]
First crash: 166d, last: 146d

Cause bisection: introduced by (bisect log) :
commit b5ea834dde6b6e7f75e51d5f66dac8cd7c97b5ef
Author: Yonghong Song <yhs@fb.com>
Date: Tue Sep 14 22:30:15 2021 +0000

  bpf: Support for new btf kind BTF_KIND_TAG

Crash: general protection fault in btf_tag_resolve (log)
Repro: C syz .config

Sample crash report:
general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
CPU: 0 PID: 3592 Comm: syz-executor914 Not tainted 5.16.0-syzkaller-11424-gb7892f7d5cb2 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:btf_type_vlen include/linux/btf.h:231 [inline]
RIP: 0010:btf_decl_tag_resolve+0x83e/0xaa0 kernel/bpf/btf.c:3910
Code: c1 ea 03 80 3c 02 00 0f 85 90 01 00 00 48 8b 1b e8 b7 c9 e6 ff 48 8d 7b 04 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <0f> b6 14 02 48 89 f8 83 e0 07 83 c0 03 38 d0 7c 08 84 d2 0f 85 2b
RSP: 0018:ffffc90001b1fa00 EFLAGS: 00010247
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff81918c09 RDI: 0000000000000004
RBP: ffff888015c32000 R08: 0000000000000008 R09: 0000000000000008
R10: ffffffff81918bb1 R11: 0000000000000001 R12: 0000000000000004
R13: 0000000000000008 R14: 0000000000000000 R15: 0000000000000005
FS:  00005555556fd300(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f98c38b8220 CR3: 0000000019537000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 btf_resolve+0x251/0x1020 kernel/bpf/btf.c:4198
 btf_check_all_types kernel/bpf/btf.c:4239 [inline]
 btf_parse_type_sec kernel/bpf/btf.c:4280 [inline]
 btf_parse kernel/bpf/btf.c:4513 [inline]
 btf_new_fd+0x19fe/0x2370 kernel/bpf/btf.c:6047
 bpf_btf_load kernel/bpf/syscall.c:4039 [inline]
 __sys_bpf+0x1cbb/0x5970 kernel/bpf/syscall.c:4679
 __do_sys_bpf kernel/bpf/syscall.c:4738 [inline]
 __se_sys_bpf kernel/bpf/syscall.c:4736 [inline]
 __x64_sys_bpf+0x75/0xb0 kernel/bpf/syscall.c:4736
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7fd57f202099
Code: 28 c3 e8 2a 14 00 00 66 2e 0f 1f 84 00 00 00 00 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 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffe9e5eb898 EFLAGS: 00000246 ORIG_RAX: 0000000000000141
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fd57f202099
RDX: 0000000000000020 RSI: 0000000020000000 RDI: 0000000000000012
RBP: 00007fd57f1c6080 R08: 0000000000000000 R09: 0000000000000000
R10: 00000000ffffffff R11: 0000000000000246 R12: 00007fd57f1c6110
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:btf_type_vlen include/linux/btf.h:231 [inline]
RIP: 0010:btf_decl_tag_resolve+0x83e/0xaa0 kernel/bpf/btf.c:3910
Code: c1 ea 03 80 3c 02 00 0f 85 90 01 00 00 48 8b 1b e8 b7 c9 e6 ff 48 8d 7b 04 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <0f> b6 14 02 48 89 f8 83 e0 07 83 c0 03 38 d0 7c 08 84 d2 0f 85 2b
RSP: 0018:ffffc90001b1fa00 EFLAGS: 00010247
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff81918c09 RDI: 0000000000000004
RBP: ffff888015c32000 R08: 0000000000000008 R09: 0000000000000008
R10: ffffffff81918bb1 R11: 0000000000000001 R12: 0000000000000004
R13: 0000000000000008 R14: 0000000000000000 R15: 0000000000000005
FS:  00005555556fd300(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020000000 CR3: 0000000019537000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
   0:	c1 ea 03             	shr    $0x3,%edx
   3:	80 3c 02 00          	cmpb   $0x0,(%rdx,%rax,1)
   7:	0f 85 90 01 00 00    	jne    0x19d
   d:	48 8b 1b             	mov    (%rbx),%rbx
  10:	e8 b7 c9 e6 ff       	callq  0xffe6c9cc
  15:	48 8d 7b 04          	lea    0x4(%rbx),%rdi
  19:	48 b8 00 00 00 00 00 	movabs $0xdffffc0000000000,%rax
  20:	fc ff df
  23:	48 89 fa             	mov    %rdi,%rdx
  26:	48 c1 ea 03          	shr    $0x3,%rdx
* 2a:	0f b6 14 02          	movzbl (%rdx,%rax,1),%edx <-- trapping instruction
  2e:	48 89 f8             	mov    %rdi,%rax
  31:	83 e0 07             	and    $0x7,%eax
  34:	83 c0 03             	add    $0x3,%eax
  37:	38 d0                	cmp    %dl,%al
  39:	7c 08                	jl     0x43
  3b:	84 d2                	test   %dl,%dl
  3d:	0f                   	.byte 0xf
  3e:	85 2b                	test   %ebp,(%rbx)

Crashes (6):
Manager Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Title
ci-upstream-bpf-kasan-gce 2022/02/03 02:09 bpf b7892f7d5cb2 4ebb2798 .config log report syz C general protection fault in btf_decl_tag_resolve
ci-upstream-net-this-kasan-gce 2022/02/03 02:09 net 3aa430d33b8d 4ebb2798 .config log report syz C general protection fault in btf_decl_tag_resolve
ci-upstream-net-kasan-gce 2022/02/03 04:44 net-next 52dae93f3bad 4ebb2798 .config log report syz C general protection fault in btf_decl_tag_resolve
ci-upstream-bpf-next-kasan-gce 2022/02/03 02:12 bpf-next dd5152ab338c 4ebb2798 .config log report syz C general protection fault in btf_decl_tag_resolve
ci-upstream-bpf-kasan-gce 2022/01/17 06:13 bpf 343e53754b21 723cfaf0 .config log report info general protection fault in btf_decl_tag_resolve
ci-upstream-bpf-next-kasan-gce 2022/01/13 17:44 bpf-next 86c7ecad3bf8 44d1319a .config log report info general protection fault in btf_decl_tag_resolve