[syzbot] [can?] WARNING in __netif_receive_skb_core
From: syzbot <hidden>
Date: 2026-09-15 15:56:41
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Hello, syzbot found the following issue on: HEAD commit: 704340f1cd0d Merge tag 'x86_urgent_for_7.3-rc4' of git://g.. git tree: upstream console+strace: https://syzkaller.appspot.com/x/log.txt?x=15a62471580000 kernel config: https://syzkaller.appspot.com/x/.config?x=8c5c3949d762a91f dashboard link: https://syzkaller.appspot.com/bug?extid=1aae11dc8d42ec1a87ec compiler: gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1580bc8e580000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=169f9905580000 Downloadable assets: disk image: https://storage.googleapis.com/syzbot-assets/192c594c6096/disk-704340f1.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/79d1488deb4b/vmlinux-704340f1.xz kernel image: https://storage.googleapis.com/syzbot-assets/fd108c2b8ca0/bzImage-704340f1.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+1aae11dc8d42ec1a87ec@syzkaller.appspotmail.com ------------[ cut here ]------------ 1 WARNING: ./include/linux/skbuff.h:3003 at skb_reset_mac_len include/linux/skbuff.h:3003 [inline], CPU#0: kworker/u8:1/13 WARNING: ./include/linux/skbuff.h:3003 at __netif_receive_skb_core.constprop.0+0x1706/0x3530 net/core/dev.c:6061, CPU#0: kworker/u8:1/13 Modules linked in: CPU: 0 UID: 0 PID: 13 Comm: kworker/u8:1 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/05/2026 Workqueue: events_unbound flush_to_ldisc RIP: 0010:skb_reset_mac_len include/linux/skbuff.h:3003 [inline] RIP: 0010:__netif_receive_skb_core.constprop.0+0x1706/0x3530 net/core/dev.c:6061 Code: de 4c 8b bc 24 e8 00 00 00 e8 86 f7 6b f8 85 db 0f 88 11 f2 ff ff 31 db 4d 8d af 81 00 00 00 e9 01 ed ff ff e8 fb fc 6b f8 90 <0f> 0b 90 31 db e9 43 eb ff ff e8 eb fc 6b f8 e8 66 af 4f f8 31 ff RSP: 0018:ffffc90000007990 EFLAGS: 00010246 RAX: 0000000000000000 RBX: 0000000000000040 RCX: 0000000000000101 RDX: ffff88801f2a0000 RSI: ffffffff89a02015 RDI: ffff88801f2a0000 RBP: 000000000000ffff R08: 0000000000000003 R09: 000000000000ffff R10: 000000000000ffff R11: 0000000000000001 R12: ffff888075f88140 R13: ffffc90000007c10 R14: ffff888075f88140 R15: ffff888075f88140 FS: 0000000000000000(0000) GS:ffff888123b59000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007ffd21e26870 CR3: 00000000729f5000 CR4: 00000000003526f0 Call Trace: <IRQ> __netif_receive_skb_one_core+0xb0/0x1e0 net/core/dev.c:6262 __netif_receive_skb+0x1f/0x120 net/core/dev.c:6377 process_backlog+0x487/0x1600 net/core/dev.c:6728 __napi_poll.constprop.0+0xaf/0x450 net/core/dev.c:7787 napi_poll net/core/dev.c:7850 [inline] net_rx_action+0xa40/0xf20 net/core/dev.c:8007 handle_softirqs+0x1e6/0x9d0 kernel/softirq.c:645 do_softirq kernel/softirq.c:546 [inline] do_softirq+0xaf/0xf0 kernel/softirq.c:533 </IRQ> <TASK> __local_bh_enable_ip+0xff/0x120 kernel/softirq.c:473 local_bh_enable include/linux/bottom_half.h:33 [inline] netif_rx net/core/dev.c:5837 [inline] netif_rx+0x93/0xb0 net/core/dev.c:5826 slcan_bump_err drivers/net/can/slcan/slcan-core.c:448 [inline] slcan_bump drivers/net/can/slcan/slcan-core.c:463 [inline] slcan_unesc drivers/net/can/slcan/slcan-core.c:476 [inline] slcan_receive_buf+0x1a66/0x1f30 drivers/net/can/slcan/slcan-core.c:807 tty_ldisc_receive_buf+0x15a/0x1a0 drivers/tty/tty_buffer.c:398 tty_port_default_receive_buf+0x70/0xb0 drivers/tty/tty_port.c:37 receive_buf drivers/tty/tty_buffer.c:452 [inline] flush_to_ldisc+0x26b/0x730 drivers/tty/tty_buffer.c:502 process_one_work+0xac7/0x1b10 kernel/workqueue.c:3396 process_scheduled_works kernel/workqueue.c:3479 [inline] worker_thread+0x5ef/0xe50 kernel/workqueue.c:3560 kthread+0x373/0x450 kernel/kthread.c:436 ret_from_fork+0x730/0xd60 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 </TASK> --- 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. 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