Subject: Re: [syzbot] [bpf?] [net?] general protection fault in dev_map_enqueue

From: syzbot <[email-masked]>
Date: Mon, 08 Apr 2024 15:03:03 -0700

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
general protection fault in dev_map_enqueue

general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN PTI
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
CPU: 0 PID: 8787 Comm: syz-executor.0 Not tainted 6.8.0-syzkaller-05236-g443574b03387-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
RIP: 0010:dev_map_enqueue+0x31/0x3e0 kernel/bpf/devmap.c:539
Code: 41 56 41 55 41 54 53 48 83 ec 18 49 89 d4 49 89 f5 48 89 fd 49 be 00 00 00 00 00 fc ff df e8 a6 42 d8 ff 48 89 e8 48 c1 e8 03 <42> 80 3c 30 00 74 08 48 89 ef e8 10 8a 3b 00 4c 8b 7d 00 48 83 c5
RSP: 0018:ffffc9000bc1f688 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffff888011815a00
RDX: 0000000000000000 RSI: ffff88802bed7070 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000005 R09: ffffffff894ff90e
R10: 0000000000000004 R11: ffff888011815a00 R12: ffff888022f4a000
R13: ffff88802bed7070 R14: dffffc0000000000 R15: ffff8880b943c088
FS:  00007f0b6b2916c0(0000) GS:ffff8880b9400000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f0b6a5a80c0 CR3: 000000002dad2000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 __xdp_do_redirect_frame net/core/filter.c:4384 [inline]
 xdp_do_redirect_frame+0x20d/0x4d0 net/core/filter.c:4438
 xdp_test_run_batch net/bpf/test_run.c:337 [inline]
 bpf_test_run_xdp_live+0xf0b/0x1f10 net/bpf/test_run.c:385
 bpf_prog_test_run_xdp+0x813/0x11b0 net/bpf/test_run.c:1268
 bpf_prog_test_run+0x33a/0x3b0 kernel/bpf/syscall.c:4240
 __sys_bpf+0x48d/0x810 kernel/bpf/syscall.c:5649
 __do_sys_bpf kernel/bpf/syscall.c:5738 [inline]
 __se_sys_bpf kernel/bpf/syscall.c:5736 [inline]
 __x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:5736
 do_syscall_64+0xfb/0x240
 entry_SYSCALL_64_after_hwframe+0x6d/0x75
RIP: 0033:0x7f0b6a47dda9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 20 00 00 90 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 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f0b6b2910c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000141
RAX: ffffffffffffffda RBX: 00007f0b6a5abf80 RCX: 00007f0b6a47dda9
RDX: 0000000000000050 RSI: 0000000020000240 RDI: 000000000000000a
RBP: 00007f0b6a4ca47a R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000000b R14: 00007f0b6a5abf80 R15: 00007ffe8c70ed58
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:dev_map_enqueue+0x31/0x3e0 kernel/bpf/devmap.c:539
Code: 41 56 41 55 41 54 53 48 83 ec 18 49 89 d4 49 89 f5 48 89 fd 49 be 00 00 00 00 00 fc ff df e8 a6 42 d8 ff 48 89 e8 48 c1 e8 03 <42> 80 3c 30 00 74 08 48 89 ef e8 10 8a 3b 00 4c 8b 7d 00 48 83 c5
RSP: 0018:ffffc9000bc1f688 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffff888011815a00
RDX: 0000000000000000 RSI: ffff88802bed7070 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000005 R09: ffffffff894ff90e
R10: 0000000000000004 R11: ffff888011815a00 R12: ffff888022f4a000
R13: ffff88802bed7070 R14: dffffc0000000000 R15: ffff8880b943c088
FS:  00007f0b6b2916c0(0000) GS:ffff8880b9400000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f0b6a5a80c0 CR3: 000000002dad2000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
   0:	41 56                	push   %r14
   2:	41 55                	push   %r13
   4:	41 54                	push   %r12
   6:	53                   	push   %rbx
   7:	48 83 ec 18          	sub    $0x18,%rsp
   b:	49 89 d4             	mov    %rdx,%r12
   e:	49 89 f5             	mov    %rsi,%r13
  11:	48 89 fd             	mov    %rdi,%rbp
  14:	49 be 00 00 00 00 00 	movabs $0xdffffc0000000000,%r14
  1b:	fc ff df
  1e:	e8 a6 42 d8 ff       	call   0xffd842c9
  23:	48 89 e8             	mov    %rbp,%rax
  26:	48 c1 e8 03          	shr    $0x3,%rax
* 2a:	42 80 3c 30 00       	cmpb   $0x0,(%rax,%r14,1) <-- trapping instruction
  2f:	74 08                	je     0x39
  31:	48 89 ef             	mov    %rbp,%rdi
  34:	e8 10 8a 3b 00       	call   0x3b8a49
  39:	4c 8b 7d 00          	mov    0x0(%rbp),%r15
  3d:	48                   	rex.W
  3e:	83                   	.byte 0x83
  3f:	c5                   	.byte 0xc5

Tested on:

commit:         443574b0 riscv, bpf: Fix kfunc parameters incompatibil..
git tree:       https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf.git
console output: https://syzkaller.appspot.com/x/log.txt?x=11ac5323180000
kernel config:  https://syzkaller.appspot.com/x/.config?x=6fb1be60a193d440
dashboard link: https://syzkaller.appspot.com/bug?extid=af9492708df9797198d6
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
patch:          https://syzkaller.appspot.com/x/patch.diff?x=154653d3180000