Date: Thu, 25 Jan 2024 10:17:13 -0800
From: Kui-Feng Lee <sinquersw@...il.com>
To: Martin KaFai Lau <martin.lau@...ux.dev>
Cc: syzbot <syzbot+88f0aafe5f950d7489d7@...kaller.appspotmail.com>,
 andrii@...nel.org, ast@...nel.org, bpf@...r.kernel.org,
 daniel@...earbox.net, haoluo@...gle.com, john.fastabend@...il.com,
 jolsa@...nel.org, kpsingh@...nel.org, linux-kernel@...r.kernel.org,
 martin.lau@...nel.org, netdev@...r.kernel.org, sdf@...gle.com,
 song@...nel.org, syzkaller-bugs@...glegroups.com, thinker.li@...il.com,
 yonghong.song@...ux.dev
Subject: Re: [syzbot] [bpf?] general protection fault in
 bpf_struct_ops_find_value



On 1/25/24 10:09, Martin KaFai Lau wrote:
> On 1/25/24 9:53 AM, syzbot wrote:
>> Hello,
>>
>> syzbot found the following issue on:
>>
>> HEAD commit:    d47b9f68d289 libbpf: Correct bpf_core_read.h comment 
>> wrt b..
>> git tree:       bpf-next
>> console+strace: https://syzkaller.appspot.com/x/log.txt?x=11479fe7e80000
>> kernel config:  
>> https://syzkaller.appspot.com/x/.config?x=719e6acaf392d56b
>> dashboard link: 
>> https://syzkaller.appspot.com/bug?extid=88f0aafe5f950d7489d7
>> compiler:       gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils 
>> for Debian) 2.40
>> syz repro:      
>> https://syzkaller.appspot.com/x/repro.syz?x=14ea6be3e80000
>> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=15bc199be80000
>>
>> Downloadable assets:
>> disk image: 
>> https://storage.googleapis.com/syzbot-assets/1a9b4a5622fb/disk-d47b9f68.raw.xz
>> vmlinux: 
>> https://storage.googleapis.com/syzbot-assets/dd68baeac4fd/vmlinux-d47b9f68.xz
>> kernel image: 
>> https://storage.googleapis.com/syzbot-assets/811ba9dc9ddf/bzImage-d47b9f68.xz
>>
>> The issue was bisected to:
>>
>> commit fcc2c1fb0651477c8ed78a3a293c175ccd70697a
>> Author: Kui-Feng Lee <thinker.li@...il.com>
>> Date:   Fri Jan 19 22:49:59 2024 +0000
>>
>>      bpf: pass attached BTF to the bpf_struct_ops subsystem
>>
>> bisection log:  
>> https://syzkaller.appspot.com/x/bisect.txt?x=106a04c3e80000
>> final oops:     
>> https://syzkaller.appspot.com/x/report.txt?x=126a04c3e80000
>> console output: https://syzkaller.appspot.com/x/log.txt?x=146a04c3e80000
>>
>> IMPORTANT: if you fix the issue, please add the following tag to the 
>> commit:
>> Reported-by: syzbot+88f0aafe5f950d7489d7@...kaller.appspotmail.com
>> Fixes: fcc2c1fb0651 ("bpf: pass attached BTF to the bpf_struct_ops 
>> subsystem")
>>
>> general protection fault, probably for non-canonical address 
>> 0xdffffc0000000011: 0000 [#1] PREEMPT SMP KASAN
>> KASAN: null-ptr-deref in range [0x0000000000000088-0x000000000000008f]
>> CPU: 0 PID: 5058 Comm: syz-executor257 Not tainted 
>> 6.7.0-syzkaller-12348-gd47b9f68d289 #0
>> Hardware name: Google Google Compute Engine/Google Compute Engine, 
>> BIOS Google 11/17/2023
>> RIP: 0010:bpf_struct_ops_find_value+0x49/0x140 kernel/bpf/btf.c:8763
>> Code: 7d ea dd ff 45 85 e4 0f 84 d7 00 00 00 e8 ff ee dd ff 48 8d bb 
>> 88 00 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <80> 3c 
>> 02 00 0f 85 dc 00 00 00 48 8b 9b 88 00 00 00 48 85 db 0f 84
>> RSP: 0018:ffffc90003bb7b20 EFLAGS: 00010206
>> RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffffffff81aa3283
>> RDX: 0000000000000011 RSI: ffffffff81aa3291 RDI: 0000000000000088
>> RBP: ffffc90003bb7dd0 R08: 0000000000000005 R09: 0000000000000000
>> R10: 0000000000000002 R11: 0000000000000000 R12: 0000000000000002
>> R13: 000000000000001a R14: ffffffff8ad6bca0 R15: ffffc90003bb7e04
>> FS:  0000555556ed2380(0000) GS:ffff8880b9800000(0000) 
>> knlGS:0000000000000000
>> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>> CR2: 000000000160d398 CR3: 000000007809c000 CR4: 00000000003506f0
>> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
>> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
>> Call Trace:
>>   <TASK>
>>   bpf_struct_ops_map_alloc+0x12f/0x5d0 kernel/bpf/bpf_struct_ops.c:674
> 
> The check should be IS_ERR_"OR_NULL"(btf).  Kui-Feng, please take a 
> look. Thanks.

Sure!

> 
>>   map_create+0x548/0x1b90 kernel/bpf/syscall.c:1237
>>   __sys_bpf+0xa32/0x4a00 kernel/bpf/syscall.c:5445
>>   __do_sys_bpf kernel/bpf/syscall.c:5567 [inline]
>>   __se_sys_bpf kernel/bpf/syscall.c:5565 [inline]
>>   __x64_sys_bpf+0x78/0xc0 kernel/bpf/syscall.c:5565
>>   do_syscall_x64 arch/x86/entry/common.c:52 [inline]
>>   do_syscall_64+0xd3/0x250 arch/x86/entry/common.c:83
>>   entry_SYSCALL_64_after_hwframe+0x63/0x6b
>> RIP: 0033:0x7f9f205ef2e9
>> Code: 48 83 c4 28 c3 e8 37 17 00 00 0f 1f 80 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 b8 ff ff ff f7 d8 64 89 01 48
>> RSP: 002b:00007fffa4ce4088 EFLAGS: 00000246 ORIG_RAX: 0000000000000141
>> RAX: ffffffffffffffda RBX: 00007fffa4ce4268 RCX: 00007f9f205ef2e9
>> RDX: 0000000000000048 RSI: 00000000200004c0 RDI: 0000000000000000
>> RBP: 00007f9f20662610 R08: 0000000000000000 R09: 0000000000000000
>> R10: 00000000ffffffff R11: 0000000000000246 R12: 0000000000000001
>> R13: 00007fffa4ce4258 R14: 0000000000000001 R15: 0000000000000001
>>   </TASK>
>> Modules linked in:
>> ---[ end trace 0000000000000000 ]---
>> RIP: 0010:bpf_struct_ops_find_value+0x49/0x140 kernel/bpf/btf.c:8763
>> Code: 7d ea dd ff 45 85 e4 0f 84 d7 00 00 00 e8 ff ee dd ff 48 8d bb 
>> 88 00 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <80> 3c 
>> 02 00 0f 85 dc 00 00 00 48 8b 9b 88 00 00 00 48 85 db 0f 84
>> RSP: 0018:ffffc90003bb7b20 EFLAGS: 00010206
>> RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffffffff81aa3283
>> RDX: 0000000000000011 RSI: ffffffff81aa3291 RDI: 0000000000000088
>> RBP: ffffc90003bb7dd0 R08: 0000000000000005 R09: 0000000000000000
>> R10: 0000000000000002 R11: 0000000000000000 R12: 0000000000000002
>> R13: 000000000000001a R14: ffffffff8ad6bca0 R15: ffffc90003bb7e04
>> FS:  0000555556ed2380(0000) GS:ffff8880b9800000(0000) 
>> knlGS:0000000000000000
>> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>> CR2: 000000000160d398 CR3: 000000007809c000 CR4: 00000000003506f0
>> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
>> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
>> ----------------
>> Code disassembly (best guess), 4 bytes skipped:
>>     0:    45 85 e4                 test   %r12d,%r12d
>>     3:    0f 84 d7 00 00 00        je     0xe0
>>     9:    e8 ff ee dd ff           call   0xffddef0d
>>     e:    48 8d bb 88 00 00 00     lea    0x88(%rbx),%rdi
>>    15:    48 b8 00 00 00 00 00     movabs $0xdffffc0000000000,%rax
>>    1c:    fc ff df
>>    1f:    48 89 fa                 mov    %rdi,%rdx
>>    22:    48 c1 ea 03              shr    $0x3,%rdx
>> * 26:    80 3c 02 00              cmpb   $0x0,(%rdx,%rax,1) <-- 
>> trapping instruction
>>    2a:    0f 85 dc 00 00 00        jne    0x10c
>>    30:    48 8b 9b 88 00 00 00     mov    0x88(%rbx),%rbx
>>    37:    48 85 db                 test   %rbx,%rbx
>>    3a:    0f                       .byte 0xf
>>    3b:    84                       .byte 0x84
>>
>>
>> ---
>> 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@...glegroups.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
>>
>> If the report is already addressed, let syzbot know by replying with:
>> #syz fix: exact-commit-title
>>
>> 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.
>>
>> If you want to overwrite report's subsystems, reply with:
>> #syz set subsystems: new-subsystem
>> (See the list of subsystem names on the web dashboard)
>>
>> If the report is a duplicate of another one, reply with:
>> #syz dup: exact-subject-of-another-report
>>
>> If you want to undo deduplication, reply with:
>> #syz undup
> 

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