netlink: 104 bytes leftover after parsing attributes in process `syz-executor4'. ================================================================== BUG: KASAN: use-after-free in atomic_read include/asm-generic/atomic-instrumented.h:21 [inline] BUG: KASAN: use-after-free in refcount_sub_and_test_checked+0x97/0x2f0 lib/refcount.c:179 Read of size 4 at addr ffff8880a0060888 by task syz-executor5/4067 CPU: 0 PID: 4067 Comm: syz-executor5 Not tainted 5.0.0-rc4+ #53 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+0x1db/0x2d0 lib/dump_stack.c:113 print_address_description.cold+0x7c/0x20d mm/kasan/report.c:187 kasan_report.cold+0x1b/0x40 mm/kasan/report.c:317 check_memory_region_inline mm/kasan/generic.c:185 [inline] check_memory_region+0x123/0x190 mm/kasan/generic.c:191 kasan_check_read+0x11/0x20 mm/kasan/common.c:100 atomic_read include/asm-generic/atomic-instrumented.h:21 [inline] refcount_sub_and_test_checked+0x97/0x2f0 lib/refcount.c:179 refcount_dec_and_test_checked+0x1b/0x20 lib/refcount.c:212 x25_neigh_put include/net/x25.h:252 [inline] x25_connect+0xa3c/0x1050 net/x25/af_x25.c:823 __sys_connect+0x357/0x490 net/socket.c:1662 __do_sys_connect net/socket.c:1673 [inline] __se_sys_connect net/socket.c:1670 [inline] __x64_sys_connect+0x73/0xb0 net/socket.c:1670 do_syscall_64+0x1a3/0x800 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x458089 Code: 6d b7 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 3b b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007f7d7e339c78 EFLAGS: 00000246 ORIG_RAX: 000000000000002a RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000458089 RDX: 0000000000000012 RSI: 0000000020000200 RDI: 0000000000000006 RBP: 000000000073c180 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f7d7e33a6d4 R13: 00000000004be5de R14: 00000000004cecc0 R15: 00000000ffffffff Allocated by task 18053: save_stack+0x45/0xd0 mm/kasan/common.c:73 set_track mm/kasan/common.c:85 [inline] __kasan_kmalloc mm/kasan/common.c:496 [inline] __kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:469 kasan_kmalloc+0x9/0x10 mm/kasan/common.c:504 kmem_cache_alloc_trace+0x151/0x760 mm/slab.c:3609 kmalloc include/linux/slab.h:545 [inline] x25_link_device_up+0xa5/0x4f0 net/x25/x25_link.c:249 x25_device_event+0x116/0x2b0 net/x25/af_x25.c:242 notifier_call_chain+0x179/0x380 kernel/notifier.c:93 __raw_notifier_call_chain kernel/notifier.c:394 [inline] raw_notifier_call_chain+0x2e/0x40 kernel/notifier.c:401 call_netdevice_notifiers_info+0x3f/0x90 net/core/dev.c:1739 call_netdevice_notifiers_extack net/core/dev.c:1751 [inline] call_netdevice_notifiers net/core/dev.c:1765 [inline] __dev_notify_flags+0x173/0x470 net/core/dev.c:7605 dev_change_flags+0x10d/0x170 net/core/dev.c:7643 dev_ifsioc+0x359/0xa50 net/core/dev_ioctl.c:237 dev_ioctl+0x1b8/0xc70 net/core/dev_ioctl.c:488 sock_do_ioctl+0x1c1/0x3d0 net/socket.c:972 sock_ioctl+0x329/0x6b0 net/socket.c:1073 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:509 [inline] do_vfs_ioctl+0x107b/0x17d0 fs/ioctl.c:696 ksys_ioctl+0xab/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+0x1a3/0x800 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe Freed by task 4066: save_stack+0x45/0xd0 mm/kasan/common.c:73 set_track mm/kasan/common.c:85 [inline] __kasan_slab_free+0x102/0x150 mm/kasan/common.c:458 kasan_slab_free+0xe/0x10 mm/kasan/common.c:466 __cache_free mm/slab.c:3487 [inline] kfree+0xcf/0x230 mm/slab.c:3806 x25_neigh_put include/net/x25.h:253 [inline] x25_connect+0xa58/0x1050 net/x25/af_x25.c:823 __sys_connect+0x357/0x490 net/socket.c:1662 __do_sys_connect net/socket.c:1673 [inline] __se_sys_connect net/socket.c:1670 [inline] __x64_sys_connect+0x73/0xb0 net/socket.c:1670 do_syscall_64+0x1a3/0x800 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe The buggy address belongs to the object at ffff8880a00607c0 which belongs to the cache kmalloc-256 of size 256 The buggy address is located 200 bytes inside of 256-byte region [ffff8880a00607c0, ffff8880a00608c0) The buggy address belongs to the page: page:ffffea0002801800 count:1 mapcount:0 mapping:ffff88812c3f07c0 index:0xffff8880a0060b80 flags: 0x1fffc0000000200(slab) raw: 01fffc0000000200 ffffea0002460788 ffffea0002530048 ffff88812c3f07c0 raw: ffff8880a0060b80 ffff8880a0060040 0000000100000008 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff8880a0060780: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb ffff8880a0060800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff8880a0060880: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc ^ ffff8880a0060900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8880a0060980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================