================================================================== BUG: KASAN: use-after-free in x25_kill_by_device net/x25/af_x25.c:217 [inline] BUG: KASAN: use-after-free in x25_device_event+0x297/0x2b0 net/x25/af_x25.c:252 Read of size 8 at addr ffff8881b5c85ad0 by task syz-executor2/22350 CPU: 1 PID: 22350 Comm: syz-executor2 Not tainted 4.20.0-rc7+ #248 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+0x1d3/0x2c6 lib/dump_stack.c:113 print_address_description.cold.8+0x9/0x1ff mm/kasan/report.c:256 kasan_report_error mm/kasan/report.c:354 [inline] kasan_report.cold.9+0x242/0x309 mm/kasan/report.c:412 __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433 x25_kill_by_device net/x25/af_x25.c:217 [inline] x25_device_event+0x297/0x2b0 net/x25/af_x25.c:252 notifier_call_chain+0x17e/0x380 kernel/notifier.c:93 __raw_notifier_call_chain kernel/notifier.c:394 [inline] raw_notifier_call_chain+0x2d/0x40 kernel/notifier.c:401 call_netdevice_notifiers_info+0x3f/0x90 net/core/dev.c:1733 call_netdevice_notifiers net/core/dev.c:1751 [inline] __dev_notify_flags+0x29b/0x480 net/core/dev.c:7547 dev_change_flags+0xfd/0x150 net/core/dev.c:7581 dev_ifsioc+0x7d6/0xa80 net/core/dev_ioctl.c:237 dev_ioctl+0x1b5/0xcc0 net/core/dev_ioctl.c:488 sock_do_ioctl+0x1f6/0x420 net/socket.c:973 sock_ioctl+0x313/0x690 net/socket.c:1074 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:509 [inline] do_vfs_ioctl+0x1de/0x1790 fs/ioctl.c:696 ksys_ioctl+0xa9/0xd0 fs/ioctl.c:713 __do_sys_ioctl fs/ioctl.c:720 [inline] __se_sys_ioctl fs/ioctl.c:718 [inline] __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:718 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x457759 Code: fd b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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 0f 83 cb b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007f4c06d4fc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000457759 RDX: 00000000200005c0 RSI: 0000000000008914 RDI: 0000000000000005 RBP: 000000000073bfa0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f4c06d506d4 R13: 00000000004c2c32 R14: 00000000004d52f8 R15: 00000000ffffffff Allocated by task 10606: save_stack+0x43/0xd0 mm/kasan/kasan.c:448 set_track mm/kasan/kasan.c:460 [inline] kasan_kmalloc+0xc7/0xe0 mm/kasan/kasan.c:553 kmem_cache_alloc_trace+0x152/0x750 mm/slab.c:3620 kmalloc include/linux/slab.h:546 [inline] x25_link_device_up+0xb2/0x500 net/x25/x25_link.c:249 x25_device_event+0x116/0x2b0 net/x25/af_x25.c:242 notifier_call_chain+0x17e/0x380 kernel/notifier.c:93 __raw_notifier_call_chain kernel/notifier.c:394 [inline] raw_notifier_call_chain+0x2d/0x40 kernel/notifier.c:401 call_netdevice_notifiers_info+0x3f/0x90 net/core/dev.c:1733 call_netdevice_notifiers net/core/dev.c:1751 [inline] __dev_notify_flags+0x17a/0x480 net/core/dev.c:7545 dev_change_flags+0xfd/0x150 net/core/dev.c:7581 dev_ifsioc+0x7d6/0xa80 net/core/dev_ioctl.c:237 dev_ioctl+0x1b5/0xcc0 net/core/dev_ioctl.c:488 sock_do_ioctl+0x1f6/0x420 net/socket.c:973 sock_ioctl+0x313/0x690 net/socket.c:1074 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:509 [inline] do_vfs_ioctl+0x1de/0x1790 fs/ioctl.c:696 ksys_ioctl+0xa9/0xd0 fs/ioctl.c:713 __do_sys_ioctl fs/ioctl.c:720 [inline] __se_sys_ioctl fs/ioctl.c:718 [inline] __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:718 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe Freed by task 22299: save_stack+0x43/0xd0 mm/kasan/kasan.c:448 set_track mm/kasan/kasan.c:460 [inline] __kasan_slab_free+0x102/0x150 mm/kasan/kasan.c:521 kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528 __cache_free mm/slab.c:3498 [inline] kfree+0xcf/0x230 mm/slab.c:3817 x25_neigh_put include/net/x25.h:253 [inline] __x25_remove_neigh+0x233/0x310 net/x25/x25_link.c:290 x25_link_device_down+0xc7/0x130 net/x25/x25_link.c:308 x25_device_event+0x262/0x2b0 net/x25/af_x25.c:254 notifier_call_chain+0x17e/0x380 kernel/notifier.c:93 __raw_notifier_call_chain kernel/notifier.c:394 [inline] raw_notifier_call_chain+0x2d/0x40 kernel/notifier.c:401 call_netdevice_notifiers_info+0x3f/0x90 net/core/dev.c:1733 call_netdevice_notifiers net/core/dev.c:1751 [inline] __dev_notify_flags+0x29b/0x480 net/core/dev.c:7547 dev_change_flags+0xfd/0x150 net/core/dev.c:7581 dev_ifsioc+0x7d6/0xa80 net/core/dev_ioctl.c:237 dev_ioctl+0x1b5/0xcc0 net/core/dev_ioctl.c:488 sock_do_ioctl+0x1f6/0x420 net/socket.c:973 sock_ioctl+0x313/0x690 net/socket.c:1074 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:509 [inline] do_vfs_ioctl+0x1de/0x1790 fs/ioctl.c:696 ksys_ioctl+0xa9/0xd0 fs/ioctl.c:713 __do_sys_ioctl fs/ioctl.c:720 [inline] __se_sys_ioctl fs/ioctl.c:718 [inline] __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:718 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe The buggy address belongs to the object at ffff8881b5c85ac0 which belongs to the cache kmalloc-256 of size 256 The buggy address is located 16 bytes inside of 256-byte region [ffff8881b5c85ac0, ffff8881b5c85bc0) The buggy address belongs to the page: page:ffffea0006d72140 count:1 mapcount:0 mapping:ffff8881da8007c0 index:0xffff8881b5c85e80 flags: 0x2fffc0000000200(slab) raw: 02fffc0000000200 ffffea00075f33c8 ffffea000731be48 ffff8881da8007c0 raw: ffff8881b5c85e80 ffff8881b5c850c0 0000000100000008 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff8881b5c85980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8881b5c85a00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff8881b5c85a80: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb ^ ffff8881b5c85b00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8881b5c85b80: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc ==================================================================