------------[ cut here ]------------
WARNING: CPU: 1 PID: 16624 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: 1 UID: 0 PID: 16624 Comm: syz.1.4552 Not tainted 6.11.0-syzkaller #0
Hardware name: ARM-Versatile Express
Call trace: 
[<819839d8>] (dump_backtrace) from [<81983ad4>] (show_stack+0x18/0x1c arch/arm/kernel/traps.c:257)
 r7:00000000 r6:826228c4 r5:00000000 r4:82035550
[<81983abc>] (show_stack) from [<819a1a38>] (__dump_stack lib/dump_stack.c:93 [inline])
[<81983abc>] (show_stack) from [<819a1a38>] (dump_stack_lvl+0x54/0x7c lib/dump_stack.c:119)
[<819a19e4>] (dump_stack_lvl) from [<819a1a78>] (dump_stack+0x18/0x1c lib/dump_stack.c:128)
 r5:00000000 r4:8286ed18
[<819a1a60>] (dump_stack) from [<8198457c>] (panic+0x120/0x370 kernel/panic.c:354)
[<8198445c>] (panic) from [<802421cc>] (check_panic_on_warn kernel/panic.c:243 [inline])
[<8198445c>] (panic) from [<802421cc>] (get_taint+0x0/0x1c kernel/panic.c:238)
 r3:8260c5c4 r2:00000001 r1:8201dd08 r0:82025ad4
 r7:80832e10
[<80242158>] (check_panic_on_warn) from [<8024232c>] (__warn+0x80/0x188 kernel/panic.c:748)
[<802422ac>] (__warn) from [<8024261c>] (warn_slowpath_fmt+0x1e8/0x1f4 kernel/panic.c:783)
 r8:00000009 r7:82084040 r6:eb581c84 r5:84528000 r4:00000000
[<80242438>] (warn_slowpath_fmt) from [<80832e10>] (refcount_warn_saturate+0x13c/0x174 lib/refcount.c:28)
 r10:00000000 r9:848c1284 r8:00000000 r7:00000000 r6:81811b44 r5:00000002
 r4:856d9f00
[<80832cd4>] (refcount_warn_saturate) from [<8148453c>] (__refcount_sub_and_test include/linux/refcount.h:275 [inline])
[<80832cd4>] (refcount_warn_saturate) from [<8148453c>] (__refcount_dec_and_test include/linux/refcount.h:307 [inline])
[<80832cd4>] (refcount_warn_saturate) from [<8148453c>] (refcount_dec_and_test include/linux/refcount.h:325 [inline])
[<80832cd4>] (refcount_warn_saturate) from [<8148453c>] (skb_unref include/linux/skbuff.h:1232 [inline])
[<80832cd4>] (refcount_warn_saturate) from [<8148453c>] (__sk_skb_reason_drop net/core/skbuff.c:1213 [inline])
[<80832cd4>] (refcount_warn_saturate) from [<8148453c>] (sk_skb_reason_drop+0x1d8/0x248 net/core/skbuff.c:1241)
[<81484364>] (sk_skb_reason_drop) from [<81811b44>] (kfree_skb_reason include/linux/skbuff.h:1262 [inline])
[<81484364>] (sk_skb_reason_drop) from [<81811b44>] (kfree_skb include/linux/skbuff.h:1271 [inline])
[<81484364>] (sk_skb_reason_drop) from [<81811b44>] (j1939_session_destroy+0x78/0x200 net/can/j1939/transport.c:282)
 r9:848c1284 r8:00000000 r7:eb581f38 r6:84b4f450 r5:84b4f400 r4:856d9f00
[<81811acc>] (j1939_session_destroy) from [<81812e60>] (__j1939_session_release net/can/j1939/transport.c:294 [inline])
[<81811acc>] (j1939_session_destroy) from [<81812e60>] (kref_put include/linux/kref.h:65 [inline])
[<81811acc>] (j1939_session_destroy) from [<81812e60>] (j1939_session_put+0x54/0x58 net/can/j1939/transport.c:299)
 r6:84b4f400 r5:830a2280 r4:00000004
[<81812e0c>] (j1939_session_put) from [<81810e94>] (j1939_sk_send_loop net/can/j1939/socket.c:1202 [inline])
[<81812e0c>] (j1939_session_put) from [<81810e94>] (j1939_sk_sendmsg+0x41c/0x548 net/can/j1939/socket.c:1277)
[<81810a78>] (j1939_sk_sendmsg) from [<8146f24c>] (sock_sendmsg_nosec net/socket.c:730 [inline])
[<81810a78>] (j1939_sk_sendmsg) from [<8146f24c>] (__sock_sendmsg+0x44/0x78 net/socket.c:745)
 r10:00000000 r9:eb581dd4 r8:eb581dd4 r7:00000000 r6:830a2280 r5:eb581f38
 r4:00000000
[<8146f208>] (__sock_sendmsg) from [<81470250>] (____sys_sendmsg+0x2ac/0x2cc net/socket.c:2603)
 r7:00000000 r6:00000000 r5:830a2280 r4:eb581f38
[<8146ffa4>] (____sys_sendmsg) from [<814721bc>] (___sys_sendmsg+0x9c/0xd0 net/socket.c:2657)
 r10:eb581e34 r9:20000180 r8:00000000 r7:00000000 r6:830a2280 r5:eb581f38
 r4:00000000
[<81472120>] (___sys_sendmsg) from [<814726d4>] (__sys_sendmsg net/socket.c:2686 [inline])
[<81472120>] (___sys_sendmsg) from [<814726d4>] (__do_sys_sendmsg net/socket.c:2695 [inline])
[<81472120>] (___sys_sendmsg) from [<814726d4>] (sys_sendmsg+0x78/0xbc net/socket.c:2693)
 r10:00000128 r9:84528000 r8:8020029c r7:00000000 r6:20000180 r5:830a2280
 r4:00000000
[<8147265c>] (sys_sendmsg) from [<80200060>] (ret_fast_syscall+0x0/0x1c arch/arm/mm/proc-v7.S:67)
Exception stack(0xeb581fa8 to 0xeb581ff0)
1fa0:                   00000000 00000000 00000004 20000180 00000000 00000000
1fc0: 00000000 00000000 002862f0 00000128 00000000 00006364 003d0f00 76b690bc
1fe0: 76b68ec0 76b68eb0 000189d0 00132da0
 r7:00000128 r6:002862f0 r5:00000000 r4:00000000
Rebooting in 86400 seconds..