Re: [moderation/CI] Re: bpf: Prep patches for static stack liveness.

Aleksandr Nogikh
2026-04-02T12:52:13Z

#syz upstream

On Thu, Apr 2, 2026 at 2:38 PM syzbot ci
<syzbot+cic39b201f25563d8b@syzkaller.appspotmail.com> wrote:
>
> syzbot ci has tested the following series
>
> [v2] bpf: Prep patches for static stack liveness.
> https://lore.kernel.org/all/20260402061744.10885-1-alexei.starovoitov@gmail.com
> * [PATCH v2 bpf-next 1/6] bpf: Do register range validation early
> * [PATCH v2 bpf-next 2/6] bpf: Sort subprogs in topological order after check_cfg()
> * [PATCH v2 bpf-next 3/6] selftests/bpf: Add tests for subprog topological ordering
> * [PATCH v2 bpf-next 4/6] bpf: Add bpf_compute_const_regs() and bpf_prune_dead_branches() passes
> * [PATCH v2 bpf-next 5/6] bpf: Move verifier helpers to header
> * [PATCH v2 bpf-next 6/6] bpf: Add helper and kfunc stack access size resolution
>
> and found the following issue:
> UBSAN: array-index-out-of-bounds in do_check
>
> Full report is available here:
> https://ci.syzbot.org/series/472db170-a3e5-4e2f-992a-f066f3ec68a0
>
> ***
>
> UBSAN: array-index-out-of-bounds in do_check
>
> tree: bpf-next
> URL: https://kernel.googlesource.com/pub/scm/linux/kernel/git/bpf/bpf-next.git
> base: 0eeb0094ba0321f0927806857b5f01c1577bc245
> arch: amd64
> compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
> config: https://ci.syzbot.org/builds/35679c0d-9085-497b-89c5-d447be366fc7/config
>
> can: raw protocol
> can: broadcast manager protocol
> can: netlink gateway - max_hops=1
> can: SAE J1939
> can: isotp protocol (max_pdu_size 8300)
> Bluetooth: RFCOMM TTY layer initialized
> Bluetooth: RFCOMM socket layer initialized
> Bluetooth: RFCOMM ver 1.11
> Bluetooth: BNEP (Ethernet Emulation) ver 1.3
> Bluetooth: BNEP filters: protocol multicast
> Bluetooth: BNEP socket layer initialized
> Bluetooth: HIDP (Human Interface Emulation) ver 1.2
> Bluetooth: HIDP socket layer initialized
> NET: Registered PF_RXRPC protocol family
> Key type rxrpc registered
> Key type rxrpc_s registered
> NET: Registered PF_KCM protocol family
> lec:lane_module_init: lec.c: initialized
> mpoa:atm_mpoa_init: mpc.c: initialized
> l2tp_core: L2TP core driver, V2.0
> l2tp_ppp: PPPoL2TP kernel driver, V2.0
> l2tp_ip: L2TP IP encapsulation support (L2TPv3)
> l2tp_netlink: L2TP netlink interface
> l2tp_eth: L2TP ethernet pseudowire support (L2TPv3)
> l2tp_ip6: L2TP IP encapsulation support for IPv6 (L2TPv3)
> NET: Registered PF_PHONET protocol family
> 8021q: 802.1Q VLAN Support v1.8
> sctp: Hash tables configured (bind 32/56)
> NET: Registered PF_RDS protocol family
> Registered RDS/infiniband transport
> Registered RDS/tcp transport
> tipc: Activated (version 2.0.0)
> NET: Registered PF_TIPC protocol family
> tipc: Started in single node mode
> smc: adding smcd device lo without pnetid
> NET: Registered PF_SMC protocol family
> 9pnet: Installing 9P2000 support
> NET: Registered PF_CAIF protocol family
> NET: Registered PF_IEEE802154 protocol family
> Key type dns_resolver registered
> Key type ceph registered
> libceph: loaded (mon/osd proto 15/24)
> batman_adv: B.A.T.M.A.N. advanced 2025.5 (compatibility version 15) loaded
> openvswitch: Open vSwitch switching datapath
> NET: Registered PF_VSOCK protocol family
> mpls_gso: MPLS GSO support
> IPI shorthand broadcast: enabled
> sched_clock: Marking stable (24350040289, 119535998)->(24496627492, -27051205)
> registered taskstats version 1
> ------------[ cut here ]------------
> UBSAN: array-index-out-of-bounds in kernel/bpf/verifier.c:21711:16
> index 10 is out of range for type 'u32[10]' (aka 'unsigned int[10]')
> CPU: 0 UID: 0 PID: 1 Comm: swapper/0 Not tainted syzkaller #0 PREEMPT(full)
> Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
> Call Trace:
> <TASK>
> dump_stack_lvl+0xe8/0x150
> ubsan_epilogue+0xa/0x30
> __ubsan_handle_out_of_bounds+0xe8/0xf0
> do_check+0x77a1/0x11d50
> do_check_common+0x21ea/0x2dc0
> bpf_check+0x242f/0x1cd90
> bpf_prog_load+0x1484/0x1ae0
> __sys_bpf+0x618/0x950
> kern_sys_bpf+0x185/0x700
> load+0x488/0xad0
> do_one_initcall+0x250/0x8d0
> do_initcall_level+0x104/0x190
> do_initcalls+0x59/0xa0
> kernel_init_freeable+0x2a6/0x3e0
> kernel_init+0x1d/0x1d0
> ret_from_fork+0x51e/0xb90
> ret_from_fork_asm+0x1a/0x30
> </TASK>
> ---[ end trace ]---
>
>
> ***
>
> If these findings have caused you to resend the series or submit a
> separate fix, please add the following tag to your commit message:
> Tested-by: syzbot@syzkaller.appspotmail.com
>
> ---
> This report is generated by a bot. It may contain errors.
> syzbot ci engineers can be reached at syzkaller@googlegroups.com.
>
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