================================================================== BUG: KASAN: use-after-free in atomic_read include/asm-generic/atomic-instrumented.h:26 [inline] BUG: KASAN: use-after-free in refcount_inc_not_zero_checked+0x81/0x200 lib/refcount.c:123 Read of size 4 at addr ffff8880934217c0 by task syz-executor283/14958 CPU: 0 PID: 14958 Comm: syz-executor283 Not tainted 5.2.0+ #67 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x172/0x1f0 lib/dump_stack.c:113 print_address_description.cold+0xd4/0x306 mm/kasan/report.c:351 __kasan_report.cold+0x1b/0x36 mm/kasan/report.c:482 kasan_report+0x12/0x17 mm/kasan/common.c:612 check_memory_region_inline mm/kasan/generic.c:185 [inline] check_memory_region+0x134/0x1a0 mm/kasan/generic.c:192 __kasan_check_read+0x11/0x20 mm/kasan/common.c:92 atomic_read include/asm-generic/atomic-instrumented.h:26 [inline] refcount_inc_not_zero_checked+0x81/0x200 lib/refcount.c:123 refcount_inc_checked+0x17/0x70 lib/refcount.c:156 sock_hold include/net/sock.h:649 [inline] nr_release+0x62/0x3e0 net/netrom/af_netrom.c:520 __sock_release+0xce/0x280 net/socket.c:590 sock_close+0x1e/0x30 net/socket.c:1268 __fput+0x2ff/0x890 fs/file_table.c:280 ____fput+0x16/0x20 fs/file_table.c:313 task_work_run+0x145/0x1c0 kernel/task_work.c:113 tracehook_notify_resume include/linux/tracehook.h:188 [inline] exit_to_usermode_loop+0x316/0x380 arch/x86/entry/common.c:163 prepare_exit_to_usermode arch/x86/entry/common.c:194 [inline] syscall_return_slowpath arch/x86/entry/common.c:274 [inline] do_syscall_64+0x5a9/0x6a0 arch/x86/entry/common.c:299 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x406881 Code: 75 14 b8 03 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 24 1a 00 00 c3 48 83 ec 08 e8 6a fc ff ff 48 89 04 24 b8 03 00 00 00 0f 05 <48> 8b 3c 24 48 89 c2 e8 b3 fc ff ff 48 89 d0 48 83 c4 08 48 3d 01 RSP: 002b:00007ffcb0ffffc0 EFLAGS: 00000293 ORIG_RAX: 0000000000000003 RAX: 0000000000000000 RBX: 0000000000000004 RCX: 0000000000406881 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000003 RBP: 00000000006dcc30 R08: 0000000120080522 R09: 0000000120080522 R10: 00007ffcb0ffffe0 R11: 0000000000000293 R12: 00007ffcb1000010 R13: 0000000000000004 R14: 00000000006dcc3c R15: 0000000000000064 Allocated by task 0: save_stack+0x23/0x90 mm/kasan/common.c:69 set_track mm/kasan/common.c:77 [inline] __kasan_kmalloc mm/kasan/common.c:487 [inline] __kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:460 kasan_kmalloc+0x9/0x10 mm/kasan/common.c:501 __do_kmalloc mm/slab.c:3655 [inline] __kmalloc+0x163/0x770 mm/slab.c:3664 kmalloc include/linux/slab.h:557 [inline] sk_prot_alloc+0x23a/0x310 net/core/sock.c:1603 sk_alloc+0x39/0xf70 net/core/sock.c:1657 nr_make_new net/netrom/af_netrom.c:476 [inline] nr_rx_frame+0x733/0x1e73 net/netrom/af_netrom.c:959 nr_loopback_timer+0x7b/0x170 net/netrom/nr_loopback.c:59 call_timer_fn+0x1ac/0x780 kernel/time/timer.c:1322 expire_timers kernel/time/timer.c:1366 [inline] __run_timers kernel/time/timer.c:1685 [inline] __run_timers kernel/time/timer.c:1653 [inline] run_timer_softirq+0x697/0x17a0 kernel/time/timer.c:1698 __do_softirq+0x262/0x98c kernel/softirq.c:292 Freed by task 14963: save_stack+0x23/0x90 mm/kasan/common.c:69 set_track mm/kasan/common.c:77 [inline] __kasan_slab_free+0x102/0x150 mm/kasan/common.c:449 kasan_slab_free+0xe/0x10 mm/kasan/common.c:457 __cache_free mm/slab.c:3425 [inline] kfree+0x10a/0x2c0 mm/slab.c:3756 sk_prot_free net/core/sock.c:1640 [inline] __sk_destruct+0x4f7/0x6e0 net/core/sock.c:1726 sk_destruct+0x86/0xa0 net/core/sock.c:1734 __sk_free+0xfb/0x360 net/core/sock.c:1745 sk_free+0x42/0x50 net/core/sock.c:1756 sock_put include/net/sock.h:1725 [inline] sock_efree+0x61/0x80 net/core/sock.c:2042 skb_release_head_state+0xeb/0x250 net/core/skbuff.c:652 skb_release_all+0x16/0x60 net/core/skbuff.c:663 __kfree_skb net/core/skbuff.c:679 [inline] kfree_skb net/core/skbuff.c:697 [inline] kfree_skb+0x101/0x3c0 net/core/skbuff.c:691 nr_accept+0x56e/0x700 net/netrom/af_netrom.c:819 __sys_accept4+0x34e/0x6a0 net/socket.c:1754 __do_sys_accept4 net/socket.c:1789 [inline] __se_sys_accept4 net/socket.c:1786 [inline] __x64_sys_accept4+0x97/0xf0 net/socket.c:1786 do_syscall_64+0xfd/0x6a0 arch/x86/entry/common.c:296 entry_SYSCALL_64_after_hwframe+0x49/0xbe The buggy address belongs to the object at ffff888093421740 which belongs to the cache kmalloc-2k of size 2048 The buggy address is located 128 bytes inside of 2048-byte region [ffff888093421740, ffff888093421f40) The buggy address belongs to the page: page:ffffea00024d0800 refcount:1 mapcount:0 mapping:ffff8880aa400e00 index:0x0 compound_mapcount: 0 flags: 0x1fffc0000010200(slab|head) raw: 01fffc0000010200 ffffea000250c988 ffff8880aa401948 ffff8880aa400e00 raw: 0000000000000000 ffff888093420640 0000000100000003 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff888093421680: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff888093421700: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb >ffff888093421780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888093421800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888093421880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ================================================================== ------------[ cut here ]------------ ODEBUG: activate not available (active state 0) object type: timer_list hint: nr_t1timer_expiry+0x0/0x340 net/netrom/nr_timer.c:157 WARNING: CPU: 0 PID: 14958 at lib/debugobjects.c:481 debug_print_object+0x168/0x250 lib/debugobjects.c:481 Modules linked in: CPU: 0 PID: 14958 Comm: syz-executor283 Tainted: G B 5.2.0+ #67 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:debug_print_object+0x168/0x250 lib/debugobjects.c:481 Code: dd 60 37 c6 87 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 b5 00 00 00 48 8b 14 dd 60 37 c6 87 48 c7 c7 60 2c c6 87 e8 00 f7 05 fe <0f> 0b 83 05 e3 33 67 06 01 48 83 c4 20 5b 41 5c 41 5d 41 5e 5d c3 RSP: 0018:ffff888091affaf0 EFLAGS: 00010082 RAX: 0000000000000000 RBX: 0000000000000005 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffffffff815c3a26 RDI: ffffed101235ff50 RBP: ffff888091affb30 R08: ffff8880906f6700 R09: ffffed1015d040f1 R10: ffffed1015d040f0 R11: ffff8880ae820787 R12: 0000000000000001 R13: ffffffff88db62e0 R14: ffffffff8161d660 R15: 1ffff1101235ff6c FS: 000055555734c880(0000) GS:ffff8880ae800000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fa750b39e78 CR3: 00000000a2d78000 CR4: 00000000001406f0 Call Trace: debug_object_activate+0x2e5/0x470 lib/debugobjects.c:680 debug_timer_activate kernel/time/timer.c:710 [inline] __mod_timer kernel/time/timer.c:1035 [inline] mod_timer+0x452/0xc10 kernel/time/timer.c:1096 sk_reset_timer+0x24/0x60 net/core/sock.c:2821 nr_start_t1timer+0x6e/0xa0 net/netrom/nr_timer.c:52 nr_release+0x1de/0x3e0 net/netrom/af_netrom.c:537 __sock_release+0xce/0x280 net/socket.c:590 sock_close+0x1e/0x30 net/socket.c:1268 __fput+0x2ff/0x890 fs/file_table.c:280 ____fput+0x16/0x20 fs/file_table.c:313 task_work_run+0x145/0x1c0 kernel/task_work.c:113 tracehook_notify_resume include/linux/tracehook.h:188 [inline] exit_to_usermode_loop+0x316/0x380 arch/x86/entry/common.c:163 prepare_exit_to_usermode arch/x86/entry/common.c:194 [inline] syscall_return_slowpath arch/x86/entry/common.c:274 [inline] do_syscall_64+0x5a9/0x6a0 arch/x86/entry/common.c:299 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x406881 Code: 75 14 b8 03 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 24 1a 00 00 c3 48 83 ec 08 e8 6a fc ff ff 48 89 04 24 b8 03 00 00 00 0f 05 <48> 8b 3c 24 48 89 c2 e8 b3 fc ff ff 48 89 d0 48 83 c4 08 48 3d 01 RSP: 002b:00007ffcb0ffffc0 EFLAGS: 00000293 ORIG_RAX: 0000000000000003 RAX: 0000000000000000 RBX: 0000000000000004 RCX: 0000000000406881 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000003 RBP: 00000000006dcc30 R08: 0000000120080522 R09: 0000000120080522 R10: 00007ffcb0ffffe0 R11: 0000000000000293 R12: 00007ffcb1000010 R13: 0000000000000004 R14: 00000000006dcc3c R15: 0000000000000064 irq event stamp: 940 hardirqs last enabled at (939): [] __raw_spin_unlock_irq include/linux/spinlock_api_smp.h:168 [inline] hardirqs last enabled at (939): [] _raw_spin_unlock_irq+0x28/0x90 kernel/locking/spinlock.c:199 hardirqs last disabled at (940): [] __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:108 [inline] hardirqs last disabled at (940): [] _raw_spin_lock_irqsave+0x6f/0xcd kernel/locking/spinlock.c:159 softirqs last enabled at (644): [] memcpy include/linux/string.h:359 [inline] softirqs last enabled at (644): [] fpu__copy+0x17e/0x8c0 arch/x86/kernel/fpu/core.c:195 softirqs last disabled at (642): [] fpu__copy+0xa7/0x8c0 arch/x86/kernel/fpu/core.c:183 ---[ end trace 19080e736484713c ]---