------------[ cut here ]------------
WARNING: CPU: 0 PID: 15191 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: 15191 Comm: syz.1.4237 Not tainted 6.11.0-syzkaller #0
Hardware name: ARM-Versatile Express
Call trace: 
[<81985f40>] (dump_backtrace) from [<8198603c>] (show_stack+0x18/0x1c arch/arm/kernel/traps.c:257)
 r7:00000000 r6:826228c4 r5:00000000 r4:82035a48
[<81986024>] (show_stack) from [<819a431c>] (__dump_stack lib/dump_stack.c:93 [inline])
[<81986024>] (show_stack) from [<819a431c>] (dump_stack_lvl+0x54/0x7c lib/dump_stack.c:119)
[<819a42c8>] (dump_stack_lvl) from [<819a435c>] (dump_stack+0x18/0x1c lib/dump_stack.c:128)
 r5:00000000 r4:8286dd18
[<819a4344>] (dump_stack) from [<81986b68>] (panic+0x120/0x370 kernel/panic.c:354)
[<81986a48>] (panic) from [<802421dc>] (check_panic_on_warn kernel/panic.c:243 [inline])
[<81986a48>] (panic) from [<802421dc>] (get_taint+0x0/0x1c kernel/panic.c:238)
 r3:8260c5c4 r2:00000001 r1:8201e0ec r0:82025eb8
 r7:808348c0
[<80242168>] (check_panic_on_warn) from [<8024233c>] (__warn+0x80/0x188 kernel/panic.c:748)
[<802422bc>] (__warn) from [<8024262c>] (warn_slowpath_fmt+0x1e8/0x1f4 kernel/panic.c:783)
 r8:00000009 r7:82084ad8 r6:ead41c84 r5:8483ec00 r4:00000000
[<80242448>] (warn_slowpath_fmt) from [<808348c0>] (refcount_warn_saturate+0x13c/0x174 lib/refcount.c:28)
 r10:00000000 r9:849bde84 r8:00000000 r7:00000000 r6:81813f34 r5:00000002
 r4:844823c0
[<80834784>] (refcount_warn_saturate) from [<814867d0>] (__refcount_sub_and_test include/linux/refcount.h:275 [inline])
[<80834784>] (refcount_warn_saturate) from [<814867d0>] (__refcount_dec_and_test include/linux/refcount.h:307 [inline])
[<80834784>] (refcount_warn_saturate) from [<814867d0>] (refcount_dec_and_test include/linux/refcount.h:325 [inline])
[<80834784>] (refcount_warn_saturate) from [<814867d0>] (skb_unref include/linux/skbuff.h:1232 [inline])
[<80834784>] (refcount_warn_saturate) from [<814867d0>] (__sk_skb_reason_drop net/core/skbuff.c:1213 [inline])
[<80834784>] (refcount_warn_saturate) from [<814867d0>] (sk_skb_reason_drop+0x1d8/0x248 net/core/skbuff.c:1241)
[<814865f8>] (sk_skb_reason_drop) from [<81813f34>] (kfree_skb_reason include/linux/skbuff.h:1262 [inline])
[<814865f8>] (sk_skb_reason_drop) from [<81813f34>] (kfree_skb include/linux/skbuff.h:1271 [inline])
[<814865f8>] (sk_skb_reason_drop) from [<81813f34>] (j1939_session_destroy+0x78/0x200 net/can/j1939/transport.c:282)
 r9:849bde84 r8:00000000 r7:ead41f38 r6:8490a850 r5:8490a800 r4:844823c0
[<81813ebc>] (j1939_session_destroy) from [<81815250>] (__j1939_session_release net/can/j1939/transport.c:294 [inline])
[<81813ebc>] (j1939_session_destroy) from [<81815250>] (kref_put include/linux/kref.h:65 [inline])
[<81813ebc>] (j1939_session_destroy) from [<81815250>] (j1939_session_put+0x54/0x58 net/can/j1939/transport.c:299)
 r6:8490a800 r5:84ca7b80 r4:00000004
[<818151fc>] (j1939_session_put) from [<81813284>] (j1939_sk_send_loop net/can/j1939/socket.c:1202 [inline])
[<818151fc>] (j1939_session_put) from [<81813284>] (j1939_sk_sendmsg+0x41c/0x548 net/can/j1939/socket.c:1277)
[<81812e68>] (j1939_sk_sendmsg) from [<8147147c>] (sock_sendmsg_nosec net/socket.c:730 [inline])
[<81812e68>] (j1939_sk_sendmsg) from [<8147147c>] (__sock_sendmsg+0x44/0x78 net/socket.c:745)
 r10:00000000 r9:ead41dd4 r8:ead41dd4 r7:00000000 r6:84ca7b80 r5:ead41f38
 r4:00000000
[<81471438>] (__sock_sendmsg) from [<81472480>] (____sys_sendmsg+0x2ac/0x2cc net/socket.c:2603)
 r7:00000000 r6:00000000 r5:84ca7b80 r4:ead41f38
[<814721d4>] (____sys_sendmsg) from [<814743ec>] (___sys_sendmsg+0x9c/0xd0 net/socket.c:2657)
 r10:ead41e34 r9:20000180 r8:00000000 r7:00000000 r6:84ca7b80 r5:ead41f38
 r4:00000000
[<81474350>] (___sys_sendmsg) from [<81474904>] (__sys_sendmsg net/socket.c:2686 [inline])
[<81474350>] (___sys_sendmsg) from [<81474904>] (__do_sys_sendmsg net/socket.c:2695 [inline])
[<81474350>] (___sys_sendmsg) from [<81474904>] (sys_sendmsg+0x78/0xbc net/socket.c:2693)
 r10:00000128 r9:8483ec00 r8:8020029c r7:00000000 r6:20000180 r5:84ca7b80
 r4:00000000
[<8147488c>] (sys_sendmsg) from [<80200060>] (ret_fast_syscall+0x0/0x1c arch/arm/mm/proc-v7.S:67)
Exception stack(0xead41fa8 to 0xead41ff0)
1fa0:                   00000000 00000000 00000004 20000180 00000000 00000000
1fc0: 00000000 00000000 002862f0 00000128 00000000 00006364 003d0f00 76bad0bc
1fe0: 76bacec0 76baceb0 000189d0 00132da0
 r7:00000128 r6:002862f0 r5:00000000 r4:00000000
Rebooting in 86400 seconds..