syzbot

netlink: 44 bytes leftover after parsing attributes in process `syz.0.17'.
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memcpy: detected field-spanning write (size 32) of single field "&new->sel" at net/sched/cls_u32.c:853 (size 16)
WARNING: CPU: 1 PID: 4537 at net/sched/cls_u32.c:853 u32_init_knode net/sched/cls_u32.c:853 [inline]
WARNING: CPU: 1 PID: 4537 at net/sched/cls_u32.c:853 u32_change+0x1698/0x1f18 net/sched/cls_u32.c:919
Modules linked in:
CPU: 1 PID: 4537 Comm: syz.0.17 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
pstate: 62400005 (nZCv daif +PAN -UAO +TCO -DIT -SSBS BTYPE=--)
pc : u32_init_knode net/sched/cls_u32.c:853 [inline]
pc : u32_change+0x1698/0x1f18 net/sched/cls_u32.c:919
lr : u32_init_knode net/sched/cls_u32.c:853 [inline]
lr : u32_change+0x1698/0x1f18 net/sched/cls_u32.c:919
sp : ffff800021646be0
x29: ffff800021646d40 x28: ffff0000d4b8c000 x27: 0000000000000000
x26: 1fffe0001a97180d x25: ffff0000d4b98400 x24: ffff0000d4b8c400
x23: 0000000000000010 x22: ffff7000042c8d8c x21: dfff800000000000
x20: ffff800021647400 x19: ffff800017c11000 x18: ffff800011babf60
x17: 20646c6569662065 x16: ffff800011a529a8 x15: 0000000000000000
x14: 0000000000000001 x13: 1fffe00033ea39a3 x12: 0000000000ff0100
x11: ff00800008194b40 x10: 0000000000000000 x9 : 836b2d3191fa7400
x8 : 836b2d3191fa7400 x7 : 0000000000000001 x6 : 0000000000000001
x5 : ffff800021646678 x4 : ffff800015324ea0 x3 : ffff80000853974c
x2 : 0000000000000001 x1 : 0000000100000000 x0 : 0000000000000000
Call trace:
 u32_init_knode net/sched/cls_u32.c:853 [inline]
 u32_change+0x1698/0x1f18 net/sched/cls_u32.c:919
 tc_new_tfilter+0xf60/0x1474 net/sched/cls_api.c:2194
 rtnetlink_rcv_msg+0x6d8/0xcdc net/core/rtnetlink.c:6149
 netlink_rcv_skb+0x218/0x3e8 net/netlink/af_netlink.c:2511
 rtnetlink_rcv+0x28/0x38 net/core/rtnetlink.c:6176
 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
 netlink_unicast+0x60c/0x814 net/netlink/af_netlink.c:1344
 netlink_sendmsg+0x6f4/0x9c0 net/netlink/af_netlink.c:1872
 sock_sendmsg_nosec net/socket.c:718 [inline]
 __sock_sendmsg net/socket.c:730 [inline]
 ____sys_sendmsg+0x5c8/0x938 net/socket.c:2518
 ___sys_sendmsg net/socket.c:2572 [inline]
 __sys_sendmmsg+0x344/0x834 net/socket.c:2658
 __do_sys_sendmmsg net/socket.c:2687 [inline]
 __se_sys_sendmmsg net/socket.c:2684 [inline]
 __arm64_sys_sendmmsg+0xa0/0xbc net/socket.c:2684
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x290 arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140
 do_el0_svc+0x58/0x130 arch/arm64/kernel/syscall.c:204
 el0_svc+0x58/0x128 arch/arm64/kernel/entry-common.c:637
 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585
irq event stamp: 2184
hardirqs last  enabled at (2183): [<ffff800008310650>] __up_console_sem+0xb4/0xfc kernel/printk/printk.c:261
hardirqs last disabled at (2184): [<ffff800011a4ebe4>] el1_dbg+0x24/0x80 arch/arm64/kernel/entry-common.c:405
softirqs last  enabled at (2178): [<ffff8000081acd08>] softirq_handle_end kernel/softirq.c:439 [inline]
softirqs last  enabled at (2178): [<ffff8000081acd08>] handle_softirqs+0xaec/0xc60 kernel/softirq.c:624
softirqs last disabled at (2067): [<ffff800008020e4c>] __do_softirq+0x14/0x20 kernel/softirq.c:630
---[ end trace 0000000000000000 ]---
Zero length message leads to an empty skb