------------[ cut here ]------------
refcount_t: underflow; use-after-free.
WARNING: CPU: 0 PID: 7867 at lib/refcount.c:28 refcount_warn_saturate+0x15a/0x1d0 lib/refcount.c:28
Modules linked in:
CPU: 0 UID: 0 PID: 7867 Comm: syz.0.653 Not tainted 6.12.0-syzkaller-01518-ga5c93bfec0be #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/30/2024
RIP: 0010:refcount_warn_saturate+0x15a/0x1d0 lib/refcount.c:28
Code: 20 0b 60 8c e8 47 8a 9f fc 90 0f 0b 90 90 eb 99 e8 9b 8a de fc c6 05 68 d9 4f 0b 01 90 48 c7 c7 80 0b 60 8c e8 27 8a 9f fc 90 <0f> 0b 90 90 e9 76 ff ff ff e8 78 8a de fc c6 05 42 d9 4f 0b 01 90
RSP: 0018:ffffc90002def8e8 EFLAGS: 00010246
RAX: 19a8204ee5718300 RBX: ffff888057ffd4a4 RCX: 0000000000040000
RDX: ffffc900045ba000 RSI: 0000000000031eda RDI: 0000000000031edb
RBP: 0000000000000003 R08: ffffffff8155e382 R09: fffffbfff1cfa48c
R10: dffffc0000000000 R11: fffffbfff1cfa48c R12: ffff888031b1d468
R13: ffff888057ffd4a4 R14: 1ffff11006363a98 R15: ffff888031b1d400
FS:  00007fb7cc7c56c0(0000) GS:ffff8880b8600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020001800 CR3: 0000000077b34000 CR4: 00000000003526f0
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: 0033:0x7fb7cb97e759
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:00007fb7cc7c5038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fb7cbb35f80 RCX: 00007fb7cb97e759
RDX: 0000000000000000 RSI: 0000000020000180 RDI: 0000000000000004
RBP: 00007fb7cb9f175e R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fb7cbb35f80 R15: 00007ffc2b48e898
 </TASK>