[syzbot] [bpf?] WARNING in __mark_chain_precision (3)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 577a4ee0b96f Add linux-next specific files for 20231206
git tree: linux-next
console+strace: https://syzkaller.appspot.com/x/log.txt?x=16eee286e80000
kernel config: https://syzkaller.appspot.com/x/.config?x=a3081237da77b539
dashboard link: https://syzkaller.appspot.com/bug?extid=4d6330e14407721955eb
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=16a19474e80000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=11abb46ae80000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/14bcd8d77be7/disk-577a4ee0.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/9f03a87f3ac1/vmlinux-577a4ee0.xz
kernel image: https://storage.googleapis.com/syzbot-assets/0c655bc6a307/bzImage-577a4ee0.xz

The issue was bisected to:

commit 41f6f64e6999a837048b1bd13a2f8742964eca6b
Author: Andrii Nakryiko <and...@kernel.org>
Date: Tue Dec 5 18:42:39 2023 +0000

bpf: support non-r10 register spill/fill to/from stack in precision tracking

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=10a03302e80000
final oops: https://syzkaller.appspot.com/x/report.txt?x=12a03302e80000
console output: https://syzkaller.appspot.com/x/log.txt?x=14a03302e80000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+4d6330...@syzkaller.appspotmail.com
Fixes: 41f6f64e6999 ("bpf: support non-r10 register spill/fill to/from stack in precision tracking")

------------[ cut here ]------------
verifier backtracking bug (stack slot out of bounds)
WARNING: CPU: 0 PID: 5066 at kernel/bpf/verifier.c:4266 __mark_chain_precision+0x2a84/0x4d60 kernel/bpf/verifier.c:4266
Modules linked in:
CPU: 0 PID: 5066 Comm: syz-executor245 Not tainted 6.7.0-rc4-next-20231206-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/10/2023
RIP: 0010:__mark_chain_precision+0x2a84/0x4d60 kernel/bpf/verifier.c:4266
Code: ff 89 de e8 8e e5 ec ff 84 db 0f 85 2c e1 ff ff e8 51 ea ec ff c6 05 60 54 88 0d 01 90 48 c7 c7 a0 4b d4 8a e8 2d d9 b2 ff 90 <0f> 0b 90 90 e9 09 e1 ff ff e8 2e ea ec ff 48 8d 7b 04 48 b8 00 00
RSP: 0018:ffffc90003abf2e8 EFLAGS: 00010282
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffff814e05d9
RDX: ffff888024c3bb80 RSI: ffffffff814e05e6 RDI: 0000000000000001
RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000001 R12: ffff88801b2e0000
R13: 0000000000000000 R14: 0000000000000001 R15: dffffc0000000000
FS: 0000555556ba0380(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f6c37df1b10 CR3: 0000000074a2e000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
mark_chain_precision kernel/bpf/verifier.c:4314 [inline]
check_cond_jmp_op+0xea0/0x72b0 kernel/bpf/verifier.c:14724
do_check kernel/bpf/verifier.c:17516 [inline]
do_check_common+0x8cbc/0xe8e0 kernel/bpf/verifier.c:19955
do_check_main kernel/bpf/verifier.c:20046 [inline]
bpf_check+0x5129/0xa420 kernel/bpf/verifier.c:20683
bpf_prog_load+0x1533/0x2200 kernel/bpf/syscall.c:2742
__sys_bpf+0xbf7/0x49d0 kernel/bpf/syscall.c:5414
__do_sys_bpf kernel/bpf/syscall.c:5518 [inline]
__se_sys_bpf kernel/bpf/syscall.c:5516 [inline]
__x64_sys_bpf+0x78/0xc0 kernel/bpf/syscall.c:5516
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x40/0x110 arch/x86/entry/common.c:82
entry_SYSCALL_64_after_hwframe+0x62/0x6a
RIP: 0033:0x7f3f5a049af9
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:00007ffcd0ae5d58 EFLAGS: 00000246 ORIG_RAX: 0000000000000141
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f3f5a049af9
RDX: 0000000000000048 RSI: 00000000200017c0 RDI: 0000000000000005
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000006
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 431bde82d7b634db R14: 0000000000000001 R15: 0000000000000001
</TASK>


---
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#syz fix: exact-commit-title

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[Andrii Nakryiko]

#syz test: https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git
482d548d40b0af9af730e4869903d4433e44f014

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-and-tested-by: syzbot+4d6330...@syzkaller.appspotmail.com

Tested on:

commit: 482d548d bpf: handle fake register spill to stack with..
git tree: https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git
console output: https://syzkaller.appspot.com/x/log.txt?x=16064fcae80000
kernel config: https://syzkaller.appspot.com/x/.config?x=f8715b6ede5c4b90

dashboard link: https://syzkaller.appspot.com/bug?extid=4d6330e14407721955eb
compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40

Note: no patches were applied.
Note: testing is done by a robot and is best-effort only.

[Andrii Nakryiko]

#syz fix: 482d548d bpf: handle fake register spill to stack with
BPF_ST_MEM instruction

[Aleksandr Nogikh]

> #syz fix: 482d548d bpf: handle fake register spill to stack with
> BPF_ST_MEM instruction

It needs to stay on one line, otherwise only part of the title
is considered.

#syz fix: bpf: handle fake register spill to stack with BPF_ST_MEM instruction

[Andrii Nakryiko]

On Wed, Jan 10, 2024 at 1:15 AM Aleksandr Nogikh <nog...@google.com> wrote:
>
>
> > #syz fix: 482d548d bpf: handle fake register spill to stack with
> > BPF_ST_MEM instruction
>
> It needs to stay on one line, otherwise only part of the title
> is considered.

Gmail is not very cooperative here, unfortunately. Thanks!