------------[ cut here ]------------ refcount_t: addition on 0; use-after-free. WARNING: CPU: 0 PID: 7264 at lib/refcount.c:25 refcount_warn_saturate+0x108/0x1a0 lib/refcount.c:25 Modules linked in: CPU: 0 PID: 7264 Comm: syz-executor.0 Not tainted 5.12.0-syzkaller-15039-g9819f682e48c #0 Hardware name: linux,dummy-virt (DT) pstate: 60000005 (nZCv daif -PAN -UAO -TCO BTYPE=--) pc : refcount_warn_saturate+0x108/0x1a0 lib/refcount.c:25 lr : refcount_warn_saturate+0x108/0x1a0 lib/refcount.c:25 sp : ffff80001a477b30 x29: ffff80001a477b30 x28: ffff80001722f160 x27: ffff000016f24000 x26: ffff00000a238568 x25: 1fffe000014470ad x24: 1fffe000015d480a x23: ffff000016f24000 x22: ffff800015074fe0 x21: ffff00000f804ec0 x20: ffff000016f25108 x19: 0000000000000002 x18: ffff00006aaf1b48 x17: 0000000000000000 x16: 0000000000000000 x15: ffff00006aaf1b7c x14: 1ffff0000348eea4 x13: 0000000000000001 x12: ffff60000d560297 x11: 1fffe0000d560296 x10: ffff60000d560296 x9 : dfff800000000000 x8 : ffff00006ab014b7 x7 : 0000000000000001 x6 : 00009ffff2a9fd6a x5 : ffff00006ab014b0 x4 : 1fffe00001f009d9 x3 : dfff800000000000 x2 : 0000000000000000 x1 : 0000000000000000 x0 : ffff00000f804ec0 Call trace: refcount_warn_saturate+0x108/0x1a0 lib/refcount.c:25 __refcount_add include/linux/refcount.h:199 [inline] __refcount_inc include/linux/refcount.h:250 [inline] refcount_inc include/linux/refcount.h:267 [inline] kref_get include/linux/kref.h:45 [inline] j1939_netdev_start+0x7bc/0x900 net/can/j1939/main.c:271 j1939_sk_bind+0x2c8/0xd30 net/can/j1939/socket.c:479 __sys_bind+0x16c/0x1d0 net/socket.c:1637 __do_sys_bind net/socket.c:1648 [inline] __se_sys_bind net/socket.c:1646 [inline] __arm64_sys_bind+0x6c/0xa0 net/socket.c:1646 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x6c/0x260 arch/arm64/kernel/syscall.c:52 el0_svc_common.constprop.0+0xc4/0x1e4 arch/arm64/kernel/syscall.c:145 do_el0_svc+0xa4/0xd0 arch/arm64/kernel/syscall.c:184 el0_svc+0x24/0x3c arch/arm64/kernel/entry-common.c:408 el0_sync_handler+0x1a4/0x1b0 arch/arm64/kernel/entry-common.c:424 el0_sync+0x198/0x1c0 arch/arm64/kernel/entry.S:734 irq event stamp: 1644 hardirqs last enabled at (1643): [] __raw_spin_unlock_irq include/linux/spinlock_api_smp.h:168 [inline] hardirqs last enabled at (1643): [] _raw_spin_unlock_irq+0x78/0x15c kernel/locking/spinlock.c:199 hardirqs last disabled at (1644): [] el1_dbg+0x24/0x80 arch/arm64/kernel/entry-common.c:233 softirqs last enabled at (1626): [] _stext+0x9e0/0x1084 softirqs last disabled at (1617): [] do_softirq_own_stack include/asm-generic/softirq_stack.h:10 [inline] softirqs last disabled at (1617): [] invoke_softirq kernel/softirq.c:440 [inline] softirqs last disabled at (1617): [] __irq_exit_rcu+0x494/0x550 kernel/softirq.c:637 ---[ end trace e3c7e227c87a8496 ]---