netlink: 4 bytes leftover after parsing attributes in process `syz.0.39'.
------------[ cut here ]------------
WARNING: CPU: 0 PID: 3906 at lib/refcount.c:28 refcount_warn_saturate+0x13c/0x174 lib/refcount.c:28
refcount_t: underflow; use-after-free.
Modules linked in:
Kernel panic - not syncing: kernel: panic_on_warn set ...
CPU: 0 UID: 0 PID: 3906 Comm: syz.0.39 Not tainted 6.11.0-syzkaller #0
Hardware name: ARM-Versatile Express
Call trace: 
[<81966cb8>] (dump_backtrace) from [<81966db4>] (show_stack+0x18/0x1c arch/arm/kernel/traps.c:257)
 r7:00000000 r6:826228c4 r5:00000000 r4:8200e404
[<81966d9c>] (show_stack) from [<81984a58>] (__dump_stack lib/dump_stack.c:93 [inline])
[<81966d9c>] (show_stack) from [<81984a58>] (dump_stack_lvl+0x54/0x7c lib/dump_stack.c:119)
[<81984a04>] (dump_stack_lvl) from [<81984a98>] (dump_stack+0x18/0x1c lib/dump_stack.c:128)
 r5:00000000 r4:8286ed18
[<81984a80>] (dump_stack) from [<8196785c>] (panic+0x120/0x368 kernel/panic.c:354)
[<8196773c>] (panic) from [<802421d4>] (check_panic_on_warn kernel/panic.c:243 [inline])
[<8196773c>] (panic) from [<802421d4>] (get_taint+0x0/0x1c kernel/panic.c:238)
 r3:8260c5c4 r2:00000001 r1:81ff6c38 r0:81ffea04
 r7:8081a110
[<80242160>] (check_panic_on_warn) from [<80242328>] (__warn+0x7c/0x180 kernel/panic.c:741)
[<802422ac>] (__warn) from [<80242614>] (warn_slowpath_fmt+0x1e8/0x1f4 kernel/panic.c:774)
 r8:00000009 r7:8205cdc4 r6:dfbf5854 r5:8477ec00 r4:00000000
[<80242430>] (warn_slowpath_fmt) from [<8081a110>] (refcount_warn_saturate+0x13c/0x174 lib/refcount.c:28)
 r10:85026d00 r9:0000006c r8:84fdc81c r7:00000000 r6:817f4e34 r5:00000002
 r4:8465aa80
[<80819fd4>] (refcount_warn_saturate) from [<8146782c>] (__refcount_sub_and_test include/linux/refcount.h:275 [inline])
[<80819fd4>] (refcount_warn_saturate) from [<8146782c>] (__refcount_dec_and_test include/linux/refcount.h:307 [inline])
[<80819fd4>] (refcount_warn_saturate) from [<8146782c>] (refcount_dec_and_test include/linux/refcount.h:325 [inline])
[<80819fd4>] (refcount_warn_saturate) from [<8146782c>] (skb_unref include/linux/skbuff.h:1232 [inline])
[<80819fd4>] (refcount_warn_saturate) from [<8146782c>] (__sk_skb_reason_drop net/core/skbuff.c:1213 [inline])
[<80819fd4>] (refcount_warn_saturate) from [<8146782c>] (sk_skb_reason_drop+0x1d8/0x248 net/core/skbuff.c:1241)
[<81467654>] (sk_skb_reason_drop) from [<817f4e34>] (kfree_skb_reason include/linux/skbuff.h:1262 [inline])
[<81467654>] (sk_skb_reason_drop) from [<817f4e34>] (kfree_skb include/linux/skbuff.h:1271 [inline])
[<81467654>] (sk_skb_reason_drop) from [<817f4e34>] (j1939_session_destroy+0x78/0x200 net/can/j1939/transport.c:282)
 r9:0000006c r8:84fdc81c r7:00000000 r6:85026d50 r5:85026d00 r4:8465aa80
[<817f4dbc>] (j1939_session_destroy) from [<817f8818>] (__j1939_session_release net/can/j1939/transport.c:294 [inline])
[<817f4dbc>] (j1939_session_destroy) from [<817f8818>] (kref_put include/linux/kref.h:65 [inline])
[<817f4dbc>] (j1939_session_destroy) from [<817f8818>] (j1939_session_put net/can/j1939/transport.c:299 [inline])
[<817f4dbc>] (j1939_session_destroy) from [<817f8818>] (j1939_session_deactivate_locked net/can/j1939/transport.c:1086 [inline])
[<817f4dbc>] (j1939_session_destroy) from [<817f8818>] (j1939_session_deactivate_locked net/can/j1939/transport.c:1074 [inline])
[<817f4dbc>] (j1939_session_destroy) from [<817f8818>] (j1939_cancel_active_session+0x1f0/0x1fc net/can/j1939/transport.c:2211)
 r6:84fdc814 r5:85026d04 r4:84fdc810
[<817f8628>] (j1939_cancel_active_session) from [<817f1b74>] (j1939_netdev_notify+0x108/0x150 net/can/j1939/main.c:376)
 r10:8477ec00 r9:00000000 r8:ffffffcd r7:00000001 r6:84fdc000 r5:00000002
 r4:84fdc810
[<817f1a6c>] (j1939_netdev_notify) from [<802712e0>] (notifier_call_chain+0x74/0x1ac kernel/notifier.c:93)
 r7:00000001 r6:827e7024 r5:827e7044 r4:817f1a6c
[<8027126c>] (notifier_call_chain) from [<802714fc>] (raw_notifier_call_chain+0x20/0x28 kernel/notifier.c:461)
 r10:821c86d4 r9:00000000 r8:84e58000 r7:00000001 r6:84768000 r5:00000002
 r4:dfbf59dc
[<802714dc>] (raw_notifier_call_chain) from [<81482564>] (call_netdevice_notifiers_info+0x54/0xa0 net/core/dev.c:1996)
[<81482510>] (call_netdevice_notifiers_info) from [<81482a00>] (call_netdevice_notifiers_extack net/core/dev.c:2034 [inline])
[<81482510>] (call_netdevice_notifiers_info) from [<81482a00>] (call_netdevice_notifiers net/core/dev.c:2048 [inline])
[<81482510>] (call_netdevice_notifiers_info) from [<81482a00>] (dev_close_many+0xfc/0x150 net/core/dev.c:1589)
 r6:dfbf5a48 r5:dfbf592c r4:84e5811c
[<81482904>] (dev_close_many) from [<8148dd64>] (unregister_netdevice_many_notify+0x194/0x9c0 net/core/dev.c:11373)
 r9:00000001 r8:dfbf5a48 r7:84e5811c r6:dfbf5ab0 r5:dfbf5a48 r4:dfbf599c
[<8148dbd0>] (unregister_netdevice_many_notify) from [<8149d940>] (rtnl_delete_link net/core/rtnetlink.c:3252 [inline])
[<8148dbd0>] (unregister_netdevice_many_notify) from [<8149d940>] (rtnl_dellink+0x134/0x354 net/core/rtnetlink.c:3304)
 r10:00000001 r9:00000000 r8:00000035 r7:84768000 r6:ffffffff r5:8465a9c0
 r4:82e68000
[<8149d80c>] (rtnl_dellink) from [<8149c088>] (rtnetlink_rcv_msg+0x138/0x334 net/core/rtnetlink.c:6646)
 r9:00000000 r8:82917218 r7:8465a9c0 r6:82917218 r5:00000001 r4:82e68000
[<8149bf50>] (rtnetlink_rcv_msg) from [<81575e70>] (netlink_rcv_skb+0xc0/0x120 net/netlink/af_netlink.c:2550)
 r10:00000000 r9:00000000 r8:84768000 r7:00000024 r6:82e68000 r5:8149bf50
 r4:8465a9c0
[<81575db0>] (netlink_rcv_skb) from [<8149aa28>] (rtnetlink_rcv+0x18/0x1c net/core/rtnetlink.c:6664)
 r7:8465a9c0 r6:843a0f40 r5:00000024 r4:840fe400
[<8149aa10>] (rtnetlink_rcv) from [<81575658>] (netlink_unicast_kernel net/netlink/af_netlink.c:1331 [inline])
[<8149aa10>] (rtnetlink_rcv) from [<81575658>] (netlink_unicast+0x19c/0x29c net/netlink/af_netlink.c:1357)
[<815754bc>] (netlink_unicast) from [<81575934>] (netlink_sendmsg+0x1dc/0x43c net/netlink/af_netlink.c:1901)
 r9:00000000 r8:00000000 r7:8507c400 r6:00000024 r5:8465a9c0 r4:dfbf5f38
[<81575758>] (netlink_sendmsg) from [<8145253c>] (sock_sendmsg_nosec net/socket.c:730 [inline])
[<81575758>] (netlink_sendmsg) from [<8145253c>] (__sock_sendmsg+0x44/0x78 net/socket.c:745)
 r10:00000000 r9:dfbf5dd4 r8:dfbf5dd4 r7:00000000 r6:830a7900 r5:dfbf5f38
 r4:00000000
[<814524f8>] (__sock_sendmsg) from [<81453540>] (____sys_sendmsg+0x2ac/0x2cc net/socket.c:2603)
 r7:00000000 r6:00000000 r5:830a7900 r4:dfbf5f38
[<81453294>] (____sys_sendmsg) from [<814554ac>] (___sys_sendmsg+0x9c/0xd0 net/socket.c:2657)
 r10:dfbf5e34 r9:20000140 r8:00000000 r7:00000000 r6:830a7900 r5:dfbf5f38
 r4:00000000
[<81455410>] (___sys_sendmsg) from [<814559c4>] (__sys_sendmsg net/socket.c:2686 [inline])
[<81455410>] (___sys_sendmsg) from [<814559c4>] (__do_sys_sendmsg net/socket.c:2695 [inline])
[<81455410>] (___sys_sendmsg) from [<814559c4>] (sys_sendmsg+0x78/0xbc net/socket.c:2693)
 r10:00000128 r9:8477ec00 r8:8020029c r7:00000000 r6:20000140 r5:830a7900
 r4:00000000
[<8145594c>] (sys_sendmsg) from [<80200060>] (ret_fast_syscall+0x0/0x1c arch/arm/mm/proc-v7.S:67)
Exception stack(0xdfbf5fa8 to 0xdfbf5ff0)
5fa0:                   00000000 00000000 00000006 20000140 00000000 00000000
5fc0: 00000000 00000000 002862f0 00000128 00000000 00006364 003d0f00 76b180bc
5fe0: 76b17ec0 76b17eb0 000189d0 00132da0
 r7:00000128 r6:002862f0 r5:00000000 r4:00000000
Rebooting in 86400 seconds..