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Message-ID: <d8d13e6e-94ed-ab16-1320-7b49d2a810b9@gmail.com>
Date:   Fri, 24 Mar 2023 11:22:05 -0700
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Subject: Re: [syzbot] [bpf?] [net?] general protection fault in
 bpf_struct_ops_link_create
To:     syzbot <syzbot+71ccc0fe37abb458406b@syzkaller.appspotmail.com>,
        andrii@kernel.org, ast@kernel.org, bpf@vger.kernel.org,
        daniel@iogearbox.net, haoluo@google.com, john.fastabend@gmail.com,
        jolsa@kernel.org, kpsingh@kernel.org, kuifeng@meta.com,
        linux-kernel@vger.kernel.org, martin.lau@kernel.org,
        martin.lau@linux.dev, netdev@vger.kernel.org, sdf@google.com,
        song@kernel.org, syzkaller-bugs@googlegroups.com, yhs@fb.com
References: <00000000000091ae5305f79f447f@google.com>
Content-Language: en-US, en-ZW
From:   Kui-Feng Lee <sinquersw@gmail.com>
In-Reply-To: <00000000000091ae5305f79f447f@google.com>
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Precedence: bulk

I am investigating on this issue.

On 3/23/23 23:11, syzbot wrote:
> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    226bc6ae6405 Merge branch 'Transit between BPF TCP congest..
> git tree:       bpf-next
> console+strace: https://syzkaller.appspot.com/x/log.txt?x=139c727ac80000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=cab35c936731a347
> dashboard link: https://syzkaller.appspot.com/bug?extid=71ccc0fe37abb458406b
> compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=11ef67a1c80000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=119c20fec80000
> 
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/ac055f681ed7/disk-226bc6ae.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/3895cc8a51d2/vmlinux-226bc6ae.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/1b18bb9fae05/bzImage-226bc6ae.xz
> 
> The issue was bisected to:
> 
> commit 68b04864ca425d1894c96b8141d4fba1181f11cb
> Author: Kui-Feng Lee <kuifeng@meta.com>
> Date:   Thu Mar 23 03:24:00 2023 +0000
> 
>      bpf: Create links for BPF struct_ops maps.
> 
> bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=116731b1c80000
> final oops:     https://syzkaller.appspot.com/x/report.txt?x=136731b1c80000
> console output: https://syzkaller.appspot.com/x/log.txt?x=156731b1c80000
> 
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+71ccc0fe37abb458406b@syzkaller.appspotmail.com
> Fixes: 68b04864ca42 ("bpf: Create links for BPF struct_ops maps.")
> 
> general protection fault, probably for non-canonical address 0xdffffc0000000001: 0000 [#1] PREEMPT SMP KASAN
> KASAN: null-ptr-deref in range [0x0000000000000008-0x000000000000000f]
> CPU: 1 PID: 5081 Comm: syz-executor182 Not tainted 6.2.0-syzkaller-13084-g226bc6ae6405 #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/02/2023
> RIP: 0010:bpf_struct_ops_valid_to_reg kernel/bpf/bpf_struct_ops.c:764 [inline]
> RIP: 0010:bpf_struct_ops_link_create+0xb1/0x390 kernel/bpf/bpf_struct_ops.c:879
> Code: 95 81 eb ff 48 85 c0 48 89 c5 0f 84 9e 02 00 00 e8 24 27 dd ff 48 8d 7d 18 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <0f> b6 04 02 84 c0 74 08 3c 03 0f 8e 60 02 00 00 44 8b 65 18 bf 1a
> RSP: 0018:ffffc90003b8fc38 EFLAGS: 00010203
> RAX: dffffc0000000000 RBX: 1ffff92000771f87 RCX: 0000000000000000
> RDX: 0000000000000001 RSI: ffffffff81a7dc8c RDI: 000000000000000f
> RBP: fffffffffffffff7 R08: 0000000000000007 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000000 R12: dffffc0000000000
> R13: 000000000000002c R14: ffffc90003b8fde8 R15: 0000000000000000
> FS:  0000555556538300(0000) GS:ffff8880b9900000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 0000000000eaa388 CR3: 00000000206d2000 CR4: 00000000003506e0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> Call Trace:
>   <TASK>
>   link_create kernel/bpf/syscall.c:4585 [inline]
>   __sys_bpf+0x3b77/0x53b0 kernel/bpf/syscall.c:5129
>   __do_sys_bpf kernel/bpf/syscall.c:5163 [inline]
>   __se_sys_bpf kernel/bpf/syscall.c:5161 [inline]
>   __x64_sys_bpf+0x79/0xc0 kernel/bpf/syscall.c:5161
>   do_syscall_x64 arch/x86/entry/common.c:50 [inline]
>   do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
>   entry_SYSCALL_64_after_hwframe+0x63/0xcd
> RIP: 0033:0x7fc374490ae9
> 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:00007fffe2184578 EFLAGS: 00000246 ORIG_RAX: 0000000000000141
> RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fc374490ae9
> RDX: 0000000000000010 RSI: 0000000020001340 RDI: 000000000000001c
> RBP: 00007fc374454c90 R08: 0000000000000000 R09: 0000000000000000
> R10: 00000000ffffffff R11: 0000000000000246 R12: 00007fc374454d20
> R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
>   </TASK>
> Modules linked in:
> ---[ end trace 0000000000000000 ]---
> RIP: 0010:bpf_struct_ops_valid_to_reg kernel/bpf/bpf_struct_ops.c:764 [inline]
> RIP: 0010:bpf_struct_ops_link_create+0xb1/0x390 kernel/bpf/bpf_struct_ops.c:879
> Code: 95 81 eb ff 48 85 c0 48 89 c5 0f 84 9e 02 00 00 e8 24 27 dd ff 48 8d 7d 18 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <0f> b6 04 02 84 c0 74 08 3c 03 0f 8e 60 02 00 00 44 8b 65 18 bf 1a
> RSP: 0018:ffffc90003b8fc38 EFLAGS: 00010203
> RAX: dffffc0000000000 RBX: 1ffff92000771f87 RCX: 0000000000000000
> RDX: 0000000000000001 RSI: ffffffff81a7dc8c RDI: 000000000000000f
> RBP: fffffffffffffff7 R08: 0000000000000007 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000000 R12: dffffc0000000000
> R13: 000000000000002c R14: ffffc90003b8fde8 R15: 0000000000000000
> FS:  0000555556538300(0000) GS:ffff8880b9900000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 0000000000eaa388 CR3: 00000000206d2000 CR4: 00000000003506e0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> ----------------
> Code disassembly (best guess):
>     0:	95                   	xchg   %eax,%ebp
>     1:	81 eb ff 48 85 c0    	sub    $0xc08548ff,%ebx
>     7:	48 89 c5             	mov    %rax,%rbp
>     a:	0f 84 9e 02 00 00    	je     0x2ae
>    10:	e8 24 27 dd ff       	callq  0xffdd2739
>    15:	48 8d 7d 18          	lea    0x18(%rbp),%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 04 02          	movzbl (%rdx,%rax,1),%eax <-- trapping instruction
>    2e:	84 c0                	test   %al,%al
>    30:	74 08                	je     0x3a
>    32:	3c 03                	cmp    $0x3,%al
>    34:	0f 8e 60 02 00 00    	jle    0x29a
>    3a:	44 8b 65 18          	mov    0x18(%rbp),%r12d
>    3e:	bf                   	.byte 0xbf
>    3f:	1a                   	.byte 0x1a
> 
> 
> ---
> This report is generated by a bot. It may contain errors.
> See https://goo.gl/tpsmEJ for more information about syzbot.
> syzbot engineers can be reached at syzkaller@googlegroups.com.
> 
> syzbot will keep track of this issue. See:
> https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
> For information about bisection process see: https://goo.gl/tpsmEJ#bisection
> syzbot can test patches for this issue, for details see:
> https://goo.gl/tpsmEJ#testing-patches