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

[Jesper Dangaard Brouer <hawk@kernel.org>]

On 27/03/2024 16.19, Alexei Starovoitov wrote:
> Toke, Jesper,
> 
> please take a look.
> It's reproducible 100% of the time.
> dst is NULL in dev_map_enqueue().
> 

The `dst` (NULL) is basically `ri->tgt_value` being passed through
(unmodified) via xdp_do_redirect_frame() and __xdp_do_redirect_frame()
into dev_map_enqueue().

I think something is wrong in xdp_test_run_batch().
The `ri->tgt_value` is being set in __bpf_xdp_redirect_map(), but I
cannot see __bpf_xdp_redirect_map() being used in xdp_test_run_batch().

Toke, can you take a look at xdp_test_run_batch() and where
`ri->tgt_value` is getting set?


> On Wed, Mar 27, 2024 at 1:10 AM syzbot
> <syzbot+af9492708df9797198d6@syzkaller.appspotmail.com> wrote:
>>
>> syzbot has found a reproducer for the following issue on:
>>
>> HEAD commit:    443574b03387 riscv, bpf: Fix kfunc parameters incompatibil..
>> git tree:       bpf
>> console+strace: https://syzkaller.appspot.com/x/log.txt?x=17d370b1180000
>> 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
>> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=13d6b041180000
>> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1060cc81180000
>>
>> Downloadable assets:
>> disk image: https://storage.googleapis.com/syzbot-assets/3f355021a085/disk-443574b0.raw.xz
>> vmlinux: https://storage.googleapis.com/syzbot-assets/44cf4de7472a/vmlinux-443574b0.xz
>> kernel image: https://storage.googleapis.com/syzbot-assets/a99a36c7ad65/bzImage-443574b0.xz
>>
>> IMPORTANT: if you fix the issue, please add the following tag to the commit:
>> Reported-by: syzbot+af9492708df9797198d6@syzkaller.appspotmail.com
>>
>> general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN PTI
>> KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
>> CPU: 1 PID: 5078 Comm: syz-executor295 Not tainted 6.8.0-syzkaller-05236-g443574b03387 #0
>> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/29/2024
>> 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:ffffc90003bef688 EFLAGS: 00010246
>> RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffff888022169e00
>> RDX: 0000000000000000 RSI: ffff88802ef65070 RDI: 0000000000000000
>> RBP: 0000000000000000 R08: 0000000000000005 R09: ffffffff894ff90e
>> R10: 0000000000000004 R11: ffff888022169e00 R12: ffff888015bd0000
>> R13: ffff88802ef65070 R14: dffffc0000000000 R15: ffff8880b953c088
>> FS:  000055558e3b9380(0000) GS:ffff8880b9500000(0000) knlGS:0000000000000000
>> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>> CR2: 00007f1141b380d0 CR3: 0000000021838000 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:336 [inline]
>>   bpf_test_run_xdp_live+0xe8a/0x1e90 net/bpf/test_run.c:384
>>   bpf_prog_test_run_xdp+0x813/0x11b0 net/bpf/test_run.c:1267
>>   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: 0033:0x7f1141ac0fb9
>> Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 c1 17 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 b8 ff ff ff f7 d8 64 89 01 48
>> RSP: 002b:00007ffe180a1958 EFLAGS: 00000246 ORIG_RAX: 0000000000000141
>> RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f1141ac0fb9
>> RDX: 0000000000000048 RSI: 0000000020000340 RDI: 000000000000000a
>> RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000006
>> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
>> R13: 0000000000000000 R14: 0000000000000001 R15: 0000000000000001
>>   </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:ffffc90003bef688 EFLAGS: 00010246
>> RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffff888022169e00
>> RDX: 0000000000000000 RSI: ffff88802ef65070 RDI: 0000000000000000
>> RBP: 0000000000000000 R08: 0000000000000005 R09: ffffffff894ff90e
>> R10: 0000000000000004 R11: ffff888022169e00 R12: ffff888015bd0000
>> R13: ffff88802ef65070 R14: dffffc0000000000 R15: ffff8880b953c088
>> FS:  000055558e3b9380(0000) GS:ffff8880b9500000(0000) knlGS:0000000000000000
>> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>> CR2: 00007f1141b380d0 CR3: 0000000021838000 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
>>
>>
>> ---
>> If you want syzbot to run the reproducer, reply with:
>> #syz test: git://repo/address.git branch-or-commit-hash
>> If you attach or paste a git patch, syzbot will apply it before testing.