------------[ cut here ]------------
refcount_t: underflow; use-after-free.
WARNING: CPU: 0 PID: 5326 at lib/refcount.c:28 refcount_warn_saturate+0x15a/0x1d0 lib/refcount.c:28
Modules linked in:
CPU: 0 UID: 0 PID: 5326 Comm: syz.0.0 Not tainted 6.12.0-syzkaller-01782-gbf9aa14fc523 #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
RIP: 0010:refcount_warn_saturate+0x15a/0x1d0 lib/refcount.c:28
Code: e0 dd 60 8c e8 87 f7 96 fc 90 0f 0b 90 90 eb 99 e8 bb ff d5 fc c6 05 87 87 48 0b 01 90 48 c7 c7 40 de 60 8c e8 67 f7 96 fc 90 <0f> 0b 90 90 e9 76 ff ff ff e8 98 ff d5 fc c6 05 61 87 48 0b 01 90
RSP: 0018:ffffc9000d6af8e8 EFLAGS: 00010246
RAX: bbefae909426b300 RBX: ffff88804fa8a9a4 RCX: 0000000000040000
RDX: ffffc9000d3fa000 RSI: 00000000000009a8 RDI: 00000000000009a9
RBP: 0000000000000003 R08: ffffffff8155e432 R09: 1ffff11003f8519a
R10: dffffc0000000000 R11: ffffed1003f8519b R12: ffff8880404f5068
R13: ffff88804fa8a9a4 R14: 1ffff1100809ea18 R15: ffff8880404f5000
FS:  00007f440084a6c0(0000) GS:ffff88801fc00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f43ffb2d0f0 CR3: 0000000042ed8000 CR4: 0000000000352ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 kfree_skb_reason include/linux/skbuff.h:1262 [inline]
 kfree_skb include/linux/skbuff.h:1271 [inline]
 j1939_session_destroy net/can/j1939/transport.c:282 [inline]
 __j1939_session_release net/can/j1939/transport.c:294 [inline]
 kref_put include/linux/kref.h:65 [inline]
 j1939_session_put+0x1ed/0x440 net/can/j1939/transport.c:299
 j1939_sk_send_loop net/can/j1939/socket.c:1202 [inline]
 j1939_sk_sendmsg+0x121b/0x14c0 net/can/j1939/socket.c:1277
 sock_sendmsg_nosec net/socket.c:711 [inline]
 __sock_sendmsg+0x221/0x270 net/socket.c:726
 ____sys_sendmsg+0x52a/0x7e0 net/socket.c:2581
 ___sys_sendmsg net/socket.c:2635 [inline]
 __sys_sendmsg+0x269/0x350 net/socket.c:2667
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f43ff97e759
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f440084a038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f43ffb35f80 RCX: 00007f43ff97e759
RDX: 0000000000000000 RSI: 0000000020000180 RDI: 0000000000000004
RBP: 00007f43ff9f175e R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f43ffb35f80 R15: 00007fff0798ab18
 </TASK>