[syzbot] [bpf?] [net?] general protection fault in bpf_struct_ops_link_create

[syzbot]

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 <kui...@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+71ccc0...@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.
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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

[Daniel Borkmann]

On 3/24/23 7:11 AM, 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 <kui...@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

Kui-Feng, please take a look & fix.

> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+71ccc0...@syzkaller.appspotmail.com
> Fixes: 68b04864ca42 ("bpf: Create links for BPF struct_ops maps.")

Thanks,
Daniel

[Kui-Feng Lee]

I am investigating on this issue.