================================================================== BUG: KASAN: use-after-free in free_netdev+0x186/0x300 net/core/dev.c:9582 Read of size 8 at addr ffff8881cae404f0 by task syz-executor.0/2339 CPU: 0 PID: 2339 Comm: syz-executor.0 Not tainted 5.4.24-syzkaller-00171-g3fe2bfe139ad #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+0x1b0/0x228 lib/dump_stack.c:118 print_address_description+0x96/0x5d0 mm/kasan/report.c:374 __kasan_report+0x14b/0x1c0 mm/kasan/report.c:506 kasan_report+0x26/0x50 mm/kasan/common.c:634 __asan_report_load8_noabort+0x14/0x20 mm/kasan/generic_report.c:132 free_netdev+0x186/0x300 net/core/dev.c:9582 netdev_run_todo+0xbc4/0xe00 net/core/dev.c:9333 rtnl_unlock net/core/rtnetlink.c:112 [inline] rtnetlink_rcv_msg+0x963/0xc20 net/core/rtnetlink.c:5255 netlink_rcv_skb+0x1f0/0x460 net/netlink/af_netlink.c:2478 rtnetlink_rcv+0x1c/0x20 net/core/rtnetlink.c:5272 netlink_unicast_kernel net/netlink/af_netlink.c:1303 [inline] netlink_unicast+0x87c/0xa20 net/netlink/af_netlink.c:1329 netlink_sendmsg+0x9a7/0xd40 net/netlink/af_netlink.c:1918 sock_sendmsg_nosec net/socket.c:638 [inline] sock_sendmsg net/socket.c:658 [inline] ____sys_sendmsg+0x56f/0x860 net/socket.c:2298 ___sys_sendmsg net/socket.c:2352 [inline] __sys_sendmsg+0x26a/0x350 net/socket.c:2398 __do_sys_sendmsg net/socket.c:2407 [inline] __se_sys_sendmsg net/socket.c:2405 [inline] __x64_sys_sendmsg+0x7f/0x90 net/socket.c:2405 do_syscall_64+0xc0/0x100 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x45c4a9 Code: ad b6 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 7b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007fe08ee36c78 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 00007fe08ee376d4 RCX: 000000000045c4a9 RDX: 0000000000000000 RSI: 0000000020000140 RDI: 0000000000000005 RBP: 000000000076c060 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 00000000000009f9 R14: 00000000004cc766 R15: 000000000076c06c Allocated by task 2337: save_stack mm/kasan/common.c:69 [inline] set_track mm/kasan/common.c:77 [inline] __kasan_kmalloc+0x117/0x1b0 mm/kasan/common.c:510 kasan_kmalloc+0x9/0x10 mm/kasan/common.c:524 __kmalloc+0x102/0x310 mm/slub.c:3802 kmalloc include/linux/slab.h:561 [inline] sk_prot_alloc+0x11c/0x2f0 net/core/sock.c:1605 sk_alloc+0x35/0x300 net/core/sock.c:1659 tun_chr_open+0x7b/0x4a0 drivers/net/tun.c:3416 misc_open+0x3ea/0x440 drivers/char/misc.c:141 chrdev_open+0x60a/0x670 fs/char_dev.c:414 do_dentry_open+0x8f7/0x1070 fs/open.c:809 vfs_open+0x73/0x80 fs/open.c:926 do_last fs/namei.c:3528 [inline] path_openat+0x1681/0x42d0 fs/namei.c:3646 do_filp_open+0x1f7/0x430 fs/namei.c:3676 do_sys_open+0x36f/0x7a0 fs/open.c:1109 __do_sys_openat fs/open.c:1136 [inline] __se_sys_openat fs/open.c:1130 [inline] __x64_sys_openat+0xa2/0xb0 fs/open.c:1130 do_syscall_64+0xc0/0x100 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x44/0xa9 Freed by task 2335: save_stack mm/kasan/common.c:69 [inline] set_track mm/kasan/common.c:77 [inline] kasan_set_free_info mm/kasan/common.c:332 [inline] __kasan_slab_free+0x168/0x220 mm/kasan/common.c:471 kasan_slab_free+0xe/0x10 mm/kasan/common.c:480 slab_free_hook mm/slub.c:1424 [inline] slab_free_freelist_hook mm/slub.c:1457 [inline] slab_free mm/slub.c:3004 [inline] kfree+0x170/0x6d0 mm/slub.c:3956 sk_prot_free net/core/sock.c:1642 [inline] __sk_destruct+0x45f/0x4e0 net/core/sock.c:1726 sk_destruct net/core/sock.c:1741 [inline] __sk_free+0x35d/0x430 net/core/sock.c:1752 sk_free+0x45/0x50 net/core/sock.c:1763 sock_put include/net/sock.h:1735 [inline] __tun_detach+0x15d0/0x1a40 drivers/net/tun.c:728 tun_detach drivers/net/tun.c:740 [inline] tun_chr_close+0xb8/0xd0 drivers/net/tun.c:3452 __fput+0x295/0x710 fs/file_table.c:280 ____fput+0x15/0x20 fs/file_table.c:313 task_work_run+0x176/0x1a0 kernel/task_work.c:113 tracehook_notify_resume include/linux/tracehook.h:188 [inline] exit_to_usermode_loop arch/x86/entry/common.c:163 [inline] prepare_exit_to_usermode+0x2d8/0x370 arch/x86/entry/common.c:194 syscall_return_slowpath+0x6f/0x500 arch/x86/entry/common.c:274 do_syscall_64+0xe8/0x100 arch/x86/entry/common.c:300 entry_SYSCALL_64_after_hwframe+0x44/0xa9 The buggy address belongs to the object at ffff8881cae40000 which belongs to the cache kmalloc-2k of size 2048 The buggy address is located 1264 bytes inside of 2048-byte region [ffff8881cae40000, ffff8881cae40800) The buggy address belongs to the page: page:ffffea00072b9000 refcount:1 mapcount:0 mapping:ffff8881da802800 index:0x0 compound_mapcount: 0 flags: 0x8000000000010200(slab|head) raw: 8000000000010200 dead000000000100 dead000000000122 ffff8881da802800 raw: 0000000000000000 0000000080080008 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff8881cae40380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8881cae40400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff8881cae40480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff8881cae40500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8881cae40580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================