================================================================== BUG: KASAN: use-after-free in free_netdev+0x186/0x350 net/core/dev.c:10352 Read of size 8 at addr ffff888049aea6f8 by task syz-executor.4/23499 CPU: 1 PID: 23499 Comm: syz-executor.4 Not tainted 5.9.0-rc4-syzkaller #0 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+0x1d6/0x29e lib/dump_stack.c:118 print_address_description+0x66/0x620 mm/kasan/report.c:383 __kasan_report mm/kasan/report.c:513 [inline] kasan_report+0x132/0x1d0 mm/kasan/report.c:530 free_netdev+0x186/0x350 net/core/dev.c:10352 netdev_run_todo+0xaaa/0xc90 net/core/dev.c:10104 rtnl_unlock net/core/rtnetlink.c:112 [inline] rtnetlink_rcv_msg+0x890/0xd40 net/core/rtnetlink.c:5564 netlink_rcv_skb+0x190/0x3a0 net/netlink/af_netlink.c:2470 netlink_unicast_kernel net/netlink/af_netlink.c:1304 [inline] netlink_unicast+0x786/0x940 net/netlink/af_netlink.c:1330 netlink_sendmsg+0xa57/0xd70 net/netlink/af_netlink.c:1919 sock_sendmsg_nosec net/socket.c:651 [inline] sock_sendmsg net/socket.c:671 [inline] ____sys_sendmsg+0x519/0x800 net/socket.c:2353 ___sys_sendmsg net/socket.c:2407 [inline] __sys_sendmsg+0x2b1/0x360 net/socket.c:2440 do_syscall_64+0x31/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x45d5f9 Code: 5d b4 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 2b b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007fb11dd37c78 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 000000000002cf00 RCX: 000000000045d5f9 RDX: 0000000000000000 RSI: 0000000020000140 RDI: 0000000000000005 RBP: 000000000118d160 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000118d12c R13: 00007ffc4df9aeef R14: 00007fb11dd389c0 R15: 000000000118d12c Allocated by task 23483: kasan_save_stack mm/kasan/common.c:48 [inline] kasan_set_track mm/kasan/common.c:56 [inline] __kasan_kmalloc+0x100/0x130 mm/kasan/common.c:461 __do_kmalloc mm/slab.c:3655 [inline] __kmalloc+0x205/0x300 mm/slab.c:3664 kmalloc include/linux/slab.h:559 [inline] sk_prot_alloc+0xa7/0x2b0 net/core/sock.c:1685 sk_alloc+0x35/0x300 net/core/sock.c:1739 tun_chr_open+0x77/0x470 drivers/net/tun.c:3372 misc_open+0x346/0x3c0 drivers/char/misc.c:141 chrdev_open+0x498/0x580 fs/char_dev.c:414 do_dentry_open+0x7c8/0x1010 fs/open.c:817 do_open fs/namei.c:3251 [inline] path_openat+0x2794/0x3840 fs/namei.c:3368 do_filp_open+0x191/0x3a0 fs/namei.c:3395 do_sys_openat2+0x463/0x830 fs/open.c:1168 do_sys_open fs/open.c:1184 [inline] __do_sys_openat fs/open.c:1200 [inline] __se_sys_openat fs/open.c:1195 [inline] __x64_sys_openat+0x1c8/0x1f0 fs/open.c:1195 do_syscall_64+0x31/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9 Freed by task 23480: kasan_save_stack mm/kasan/common.c:48 [inline] kasan_set_track+0x3d/0x70 mm/kasan/common.c:56 kasan_set_free_info+0x17/0x30 mm/kasan/generic.c:355 __kasan_slab_free+0xdd/0x110 mm/kasan/common.c:422 __cache_free mm/slab.c:3418 [inline] kfree+0x113/0x200 mm/slab.c:3756 sk_prot_free net/core/sock.c:1722 [inline] __sk_destruct+0x612/0x770 net/core/sock.c:1807 tun_detach drivers/net/tun.c:708 [inline] tun_chr_close+0x113/0x130 drivers/net/tun.c:3408 __fput+0x34f/0x7b0 fs/file_table.c:281 task_work_run+0x137/0x1c0 kernel/task_work.c:141 tracehook_notify_resume include/linux/tracehook.h:188 [inline] exit_to_user_mode_loop kernel/entry/common.c:163 [inline] exit_to_user_mode_prepare+0x11a/0x1e0 kernel/entry/common.c:190 syscall_exit_to_user_mode+0x82/0x1d0 kernel/entry/common.c:265 entry_SYSCALL_64_after_hwframe+0x44/0xa9 The buggy address belongs to the object at ffff888049aea000 which belongs to the cache kmalloc-4k of size 4096 The buggy address is located 1784 bytes inside of 4096-byte region [ffff888049aea000, ffff888049aeb000) The buggy address belongs to the page: page:00000000564a372c refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x49aea head:00000000564a372c order:1 compound_mapcount:0 flags: 0xfffe0000010200(slab|head) raw: 00fffe0000010200 ffffea0001364488 ffffea0002861308 ffff8880aa440900 raw: 0000000000000000 ffff888049aea000 0000000100000001 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff888049aea580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888049aea600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff888049aea680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888049aea700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888049aea780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================