------------[ cut here ]------------
refcount_t: underflow; use-after-free.
WARNING: CPU: 1 PID: 8425 at lib/refcount.c:28 refcount_warn_saturate+0x15a/0x1d0 lib/refcount.c:28
Modules linked in:
CPU: 1 UID: 0 PID: 8425 Comm: syz.9.547 Not tainted 6.12.0-syzkaller-12038-gc4bb3a2d641c #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
RIP: 0010:refcount_warn_saturate+0x15a/0x1d0 lib/refcount.c:28
Code: a0 4b 5e 8c e8 07 52 9e fc 90 0f 0b 90 90 eb 99 e8 ab aa dd fc c6 05 c0 95 40 0b 01 90 48 c7 c7 00 4c 5e 8c e8 e7 51 9e fc 90 <0f> 0b 90 90 e9 76 ff ff ff e8 88 aa dd fc c6 05 9a 95 40 0b 01 90
RSP: 0018:ffffc90000a18620 EFLAGS: 00010246
RAX: 7751291da98c5b00 RBX: ffff88807f6b5364 RCX: ffff888029735a00
RDX: 0000000000000100 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000003 R08: ffffffff81601b22 R09: fffffbfff1cfa210
R10: dffffc0000000000 R11: fffffbfff1cfa210 R12: ffff88807dd46800
R13: ffff88807f6b5364 R14: ffff88807dd46800 R15: ffff88803418d218
FS: 00007fb2553d36c0(0000) GS:ffff8880b8700000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000008 CR3: 0000000033718000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
kfree_skb_reason include/linux/skbuff.h:1263 [inline]
kfree_skb include/linux/skbuff.h:1272 [inline]
j1939_session_skb_drop_old net/can/j1939/transport.c:347 [inline]
j1939_xtp_rx_cts_one net/can/j1939/transport.c:1445 [inline]
j1939_xtp_rx_cts+0x552/0xc70 net/can/j1939/transport.c:1484
j1939_tp_cmd_recv net/can/j1939/transport.c:2089 [inline]
j1939_tp_recv+0x8ae/0x1050 net/can/j1939/transport.c:2161
j1939_can_recv+0x732/0xb20 net/can/j1939/main.c:108
deliver net/can/af_can.c:573 [inline]
can_rcv_filter+0x359/0x7f0 net/can/af_can.c:607
can_receive+0x327/0x480 net/can/af_can.c:664
can_rcv+0x144/0x260 net/can/af_can.c:688
__netif_receive_skb_one_core net/core/dev.c:5672 [inline]
__netif_receive_skb+0x2e0/0x650 net/core/dev.c:5785
process_backlog+0x662/0x15b0 net/core/dev.c:6117
__napi_poll+0xcb/0x490 net/core/dev.c:6877
napi_poll net/core/dev.c:6946 [inline]
net_rx_action+0x89b/0x1240 net/core/dev.c:7068
handle_softirqs+0x2d4/0x9b0 kernel/softirq.c:554
__do_softirq kernel/softirq.c:588 [inline]
invoke_softirq kernel/softirq.c:428 [inline]
__irq_exit_rcu+0xf7/0x220 kernel/softirq.c:655
irq_exit_rcu+0x9/0x30 kernel/softirq.c:671
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1049 [inline]
sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1049
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
RIP: 0010:lock_acquire+0x264/0x550 kernel/locking/lockdep.c:5853
Code: 2b 00 74 08 4c 89 f7 e8 ca 80 8c 00 f6 44 24 61 02 0f 85 85 01 00 00 41 f7 c7 00 02 00 00 74 01 fb 48 c7 44 24 40 0e 36 e0 45 <4b> c7 44 25 00 00 00 00 00 43 c7 44 25 09 00 00 00 00 43 c7 44 25
RSP: 0018:ffffc90004597320 EFLAGS: 00000206
RAX: 0000000000000001 RBX: 1ffff920008b2e70 RCX: ffff8880297364d8
RDX: dffffc0000000000 RSI: ffffffff8c0aa880 RDI: ffffffff8c5e90a0
RBP: ffffc90004597470 R08: ffffffff94282887 R09: 1ffffffff2850510
R10: dffffc0000000000 R11: fffffbfff2850511 R12: 1ffff920008b2e6c
R13: dffffc0000000000 R14: ffffc90004597380 R15: 0000000000000246
rcu_lock_acquire include/linux/rcupdate.h:337 [inline]
rcu_read_lock include/linux/rcupdate.h:849 [inline]
smack_privileged_cred+0xd6/0x380 security/smack/smack_access.c:661
smack_unix_may_send+0x210/0x300 security/smack/smack_lsm.c:3915
security_unix_may_send+0xb9/0x280 security/security.c:4533
unix_dgram_sendmsg+0xcfc/0x1f80 net/unix/af_unix.c:2118
sock_sendmsg_nosec net/socket.c:711 [inline]
__sock_sendmsg+0x221/0x270 net/socket.c:726
____sys_sendmsg+0x52a/0x7e0 net/socket.c:2583
___sys_sendmsg net/socket.c:2637 [inline]
__sys_sendmmsg+0x36a/0x720 net/socket.c:2726
__do_sys_sendmmsg net/socket.c:2753 [inline]
__se_sys_sendmmsg net/socket.c:2750 [inline]
__x64_sys_sendmmsg+0xa0/0xb0 net/socket.c:2750
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: 0033:0x7fb254580849
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:00007fb2553d3058 EFLAGS: 00000246 ORIG_RAX: 0000000000000133
RAX: ffffffffffffffda RBX: 00007fb254745fa0 RCX: 00007fb254580849
RDX: 0000000000000651 RSI: 0000000020000000 RDI: 0000000000000007
RBP: 00007fb2545f3986 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fb254745fa0 R15: 00007fffe4f2e678
----------------
Code disassembly (best guess):
0: 2b 00 sub (%rax),%eax
2: 74 08 je 0xc
4: 4c 89 f7 mov %r14,%rdi
7: e8 ca 80 8c 00 call 0x8c80d6
c: f6 44 24 61 02 testb $0x2,0x61(%rsp)
11: 0f 85 85 01 00 00 jne 0x19c
17: 41 f7 c7 00 02 00 00 test $0x200,%r15d
1e: 74 01 je 0x21
20: fb sti
21: 48 c7 44 24 40 0e 36 movq $0x45e0360e,0x40(%rsp)
28: e0 45
* 2a: 4b c7 44 25 00 00 00 movq $0x0,0x0(%r13,%r12,1) <-- trapping instruction
31: 00 00
33: 43 c7 44 25 09 00 00 movl $0x0,0x9(%r13,%r12,1)
3a: 00 00
3c: 43 rex.XB
3d: c7 .byte 0xc7
3e: 44 rex.R
3f: 25 .byte 0x25