Hello, syzbot found the following issue on: HEAD commit: f40ddce8 Linux 5.11 git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=17073738d00000 kernel config: https://syzkaller.appspot.com/x/.config?x=e53d04227c52a0df dashboard link: https://syzkaller.appspot.com/bug?extid=bdf710cfc41c186fdff3 userspace arch: i386 Unfortunately, I don't have any reproducer for this issue yet. IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+bdf710cfc41c186fdff3@xxxxxxxxxxxxxxxxxxxxxxxxx vcan0: j1939_xtp_rx_dat: no tx connection found vcan0: j1939_xtp_rx_dat: no rx connection found vcan0: j1939_xtp_rx_dat: no tx connection found vcan0: j1939_xtp_rx_dat: no rx connection found ================================================================== BUG: KASAN: use-after-free in instrument_atomic_read_write include/linux/instrumented.h:101 [inline] BUG: KASAN: use-after-free in atomic_fetch_add_relaxed include/asm-generic/atomic-instrumented.h:142 [inline] BUG: KASAN: use-after-free in __refcount_add include/linux/refcount.h:193 [inline] BUG: KASAN: use-after-free in __refcount_inc include/linux/refcount.h:250 [inline] BUG: KASAN: use-after-free in refcount_inc include/linux/refcount.h:267 [inline] BUG: KASAN: use-after-free in kref_get include/linux/kref.h:45 [inline] BUG: KASAN: use-after-free in j1939_priv_get net/can/j1939/main.c:170 [inline] BUG: KASAN: use-after-free in j1939_can_recv+0x51/0x7d0 net/can/j1939/main.c:54 Write of size 4 at addr ffff888057f81058 by task syz-executor.5/17699 CPU: 0 PID: 17699 Comm: syz-executor.5 Not tainted 5.11.0-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: <IRQ> __dump_stack lib/dump_stack.c:79 [inline] dump_stack+0x107/0x163 lib/dump_stack.c:120 print_address_description.constprop.0.cold+0x5b/0x2f8 mm/kasan/report.c:230 __kasan_report mm/kasan/report.c:396 [inline] kasan_report.cold+0x79/0xd5 mm/kasan/report.c:413 check_memory_region_inline mm/kasan/generic.c:179 [inline] check_memory_region+0x13d/0x180 mm/kasan/generic.c:185 instrument_atomic_read_write include/linux/instrumented.h:101 [inline] atomic_fetch_add_relaxed include/asm-generic/atomic-instrumented.h:142 [inline] __refcount_add include/linux/refcount.h:193 [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_priv_get net/can/j1939/main.c:170 [inline] j1939_can_recv+0x51/0x7d0 net/can/j1939/main.c:54 deliver net/can/af_can.c:574 [inline] can_rcv_filter+0x5d4/0x8d0 net/can/af_can.c:608 can_receive+0x2e3/0x520 net/can/af_can.c:665 can_rcv+0x129/0x1d0 net/can/af_can.c:696 __netif_receive_skb_one_core+0x114/0x180 net/core/dev.c:5323 __netif_receive_skb+0x27/0x1c0 net/core/dev.c:5437 process_backlog+0x232/0x6c0 net/core/dev.c:6328 napi_poll net/core/dev.c:6806 [inline] net_rx_action+0x461/0xe10 net/core/dev.c:6889 __do_softirq+0x29b/0x9f6 kernel/softirq.c:343 asm_call_irq_on_stack+0xf/0x20 </IRQ> __run_on_irqstack arch/x86/include/asm/irq_stack.h:26 [inline] run_on_irqstack_cond arch/x86/include/asm/irq_stack.h:77 [inline] do_softirq_own_stack+0xaa/0xd0 arch/x86/kernel/irq_64.c:77 invoke_softirq kernel/softirq.c:226 [inline] __irq_exit_rcu kernel/softirq.c:420 [inline] irq_exit_rcu+0x134/0x200 kernel/softirq.c:432 sysvec_apic_timer_interrupt+0x4d/0x100 arch/x86/kernel/apic/apic.c:1100 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:629 RIP: 0010:__raw_spin_unlock_irq include/linux/spinlock_api_smp.h:169 [inline] RIP: 0010:_raw_spin_unlock_irq+0x25/0x40 kernel/locking/spinlock.c:199 Code: 0f 1f 44 00 00 55 48 8b 74 24 08 48 89 fd 48 83 c7 18 e8 de d6 5b f8 48 89 ef e8 86 8b 5c f8 e8 91 b1 7b f8 fb bf 01 00 00 00 <e8> c6 92 50 f8 65 8b 05 bf f8 04 77 85 c0 74 02 5d c3 e8 4b 4e 03 RSP: 0018:ffffc9000b50f880 EFLAGS: 00000202 RAX: 0000000000001967 RBX: 0000000000000001 RCX: 1ffffffff1b46a19 RDX: 0000000000000000 RSI: 0000000000000002 RDI: 0000000000000001 RBP: ffff8880b9c34c40 R08: 0000000000000001 R09: 0000000000000001 R10: ffffffff8178a8b8 R11: 0000000000000000 R12: ffff8880b9c34c40 R13: ffff8880119b1bc0 R14: ffff888028b51500 R15: ffff88806451d340 finish_lock_switch kernel/sched/core.c:4079 [inline] finish_task_switch.isra.0+0x158/0x7e0 kernel/sched/core.c:4196 context_switch kernel/sched/core.c:4330 [inline] __schedule+0x914/0x21a0 kernel/sched/core.c:5078 schedule+0xcf/0x270 kernel/sched/core.c:5157 freezable_schedule include/linux/freezer.h:172 [inline] futex_wait_queue_me+0x2a7/0x570 kernel/futex.c:2606 futex_wait+0x1db/0x580 kernel/futex.c:2708 do_futex+0x15d/0x1700 kernel/futex.c:3736 __do_sys_futex_time32 kernel/futex.c:3989 [inline] __se_sys_futex_time32 kernel/futex.c:3961 [inline] __ia32_sys_futex_time32+0x321/0x530 kernel/futex.c:3961 do_syscall_32_irqs_on arch/x86/entry/common.c:77 [inline] __do_fast_syscall_32+0x56/0x80 arch/x86/entry/common.c:139 do_fast_syscall_32+0x2f/0x70 arch/x86/entry/common.c:164 entry_SYSENTER_compat_after_hwframe+0x4d/0x5c RIP: 0023:0xf7f15549 Code: 03 74 c0 01 10 05 03 74 b8 01 10 06 03 74 b4 01 10 07 03 74 b0 01 10 08 03 74 d8 01 00 00 00 00 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 8d b4 26 00 00 00 00 8d b4 26 00 00 00 00 RSP: 002b:00000000f550f67c EFLAGS: 00000296 ORIG_RAX: 00000000000000f0 RAX: ffffffffffffffda RBX: 000000000818afc8 RCX: 0000000000000080 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 000000000818afcc RBP: 0000000000000081 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 Allocated by task 17710: kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38 kasan_set_track mm/kasan/common.c:46 [inline] set_alloc_info mm/kasan/common.c:401 [inline] ____kasan_kmalloc.constprop.0+0x82/0xa0 mm/kasan/common.c:429 kmalloc include/linux/slab.h:552 [inline] kzalloc include/linux/slab.h:682 [inline] j1939_priv_create net/can/j1939/main.c:124 [inline] j1939_netdev_start+0xfc/0x730 net/can/j1939/main.c:260 j1939_sk_bind+0x9c0/0xec0 net/can/j1939/socket.c:484 __sys_bind+0x1e9/0x250 net/socket.c:1635 __do_sys_bind net/socket.c:1646 [inline] __se_sys_bind net/socket.c:1644 [inline] __ia32_sys_bind+0x6e/0xb0 net/socket.c:1644 do_syscall_32_irqs_on arch/x86/entry/common.c:77 [inline] __do_fast_syscall_32+0x56/0x80 arch/x86/entry/common.c:139 do_fast_syscall_32+0x2f/0x70 arch/x86/entry/common.c:164 entry_SYSENTER_compat_after_hwframe+0x4d/0x5c Freed by task 17704: kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38 kasan_set_track+0x1c/0x30 mm/kasan/common.c:46 kasan_set_free_info+0x20/0x30 mm/kasan/generic.c:356 ____kasan_slab_free+0xe1/0x110 mm/kasan/common.c:362 kasan_slab_free include/linux/kasan.h:192 [inline] slab_free_hook mm/slub.c:1547 [inline] slab_free_freelist_hook+0x5d/0x150 mm/slub.c:1580 slab_free mm/slub.c:3143 [inline] kfree+0xdb/0x3b0 mm/slub.c:4139 kref_put include/linux/kref.h:65 [inline] j1939_priv_put+0x78/0xa0 net/can/j1939/main.c:165 j1939_sk_sock_destruct+0x44/0x90 net/can/j1939/socket.c:370 __sk_destruct+0x4b/0x900 net/core/sock.c:1778 sk_destruct+0xbd/0xe0 net/core/sock.c:1822 __sk_free+0xef/0x3d0 net/core/sock.c:1833 sk_free+0x78/0xa0 net/core/sock.c:1844 sock_put include/net/sock.h:1797 [inline] j1939_sk_release+0x519/0x790 net/can/j1939/socket.c:645 __sock_release+0xcd/0x280 net/socket.c:597 sock_close+0x18/0x20 net/socket.c:1256 __fput+0x283/0x920 fs/file_table.c:280 task_work_run+0xdd/0x190 kernel/task_work.c:140 tracehook_notify_resume include/linux/tracehook.h:189 [inline] exit_to_user_mode_loop kernel/entry/common.c:174 [inline] exit_to_user_mode_prepare+0x249/0x250 kernel/entry/common.c:201 __syscall_exit_to_user_mode_work kernel/entry/common.c:283 [inline] syscall_exit_to_user_mode+0x19/0x50 kernel/entry/common.c:294 __do_fast_syscall_32+0x62/0x80 arch/x86/entry/common.c:142 do_fast_syscall_32+0x2f/0x70 arch/x86/entry/common.c:164 entry_SYSENTER_compat_after_hwframe+0x4d/0x5c The buggy address belongs to the object at ffff888057f80000 which belongs to the cache kmalloc-8k of size 8192 The buggy address is located 4184 bytes inside of 8192-byte region [ffff888057f80000, ffff888057f82000) The buggy address belongs to the page: page:0000000047611f6c refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x57f80 head:0000000047611f6c order:3 compound_mapcount:0 compound_pincount:0 flags: 0xfff00000010200(slab|head) raw: 00fff00000010200 0000000000000000 0000000100000001 ffff888010c42280 raw: 0000000000000000 0000000000020002 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff888057f80f00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888057f80f80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff888057f81000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888057f81080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888057f81100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ================================================================== --- This report is generated by a bot. 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