================================================================== BUG: KASAN: use-after-free in free_netdev+0x186/0x380 net/core/dev.c:9907 Read of size 8 at addr ffff888091a7e6f8 by task syz-executor.3/11272 CPU: 1 PID: 11272 Comm: syz-executor.3 Not tainted 5.6.0-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+0x1e9/0x30e lib/dump_stack.c:118 print_address_description+0x74/0x5c0 mm/kasan/report.c:374 __kasan_report+0x103/0x190 mm/kasan/report.c:503 kasan_report+0x4d/0x80 mm/kasan/common.c:648 Allocated by task 11232: save_stack mm/kasan/common.c:72 [inline] set_track mm/kasan/common.c:80 [inline] __kasan_kmalloc+0x118/0x1c0 mm/kasan/common.c:518 __do_kmalloc mm/slab.c:3656 [inline] __kmalloc+0x24b/0x330 mm/slab.c:3665 kmalloc include/linux/slab.h:560 [inline] sk_prot_alloc+0xa7/0x2b0 net/core/sock.c:1604 sk_alloc+0x35/0x990 net/core/sock.c:1658 tun_chr_open+0x77/0x470 drivers/net/tun.c:3376 misc_open+0x346/0x3c0 drivers/char/misc.c:141 chrdev_open+0x498/0x580 fs/char_dev.c:414 do_dentry_open+0x82e/0x10b0 fs/open.c:797 do_open fs/namei.c:3229 [inline] path_openat+0x2790/0x38b0 fs/namei.c:3346 do_filp_open+0x191/0x3a0 fs/namei.c:3373 do_sys_openat2+0x463/0x770 fs/open.c:1148 do_sys_open fs/open.c:1164 [inline] __do_sys_openat fs/open.c:1178 [inline] __se_sys_openat fs/open.c:1173 [inline] __x64_sys_openat+0x1c8/0x1f0 fs/open.c:1173 do_syscall_64+0xf3/0x1b0 arch/x86/entry/common.c:295 entry_SYSCALL_64_after_hwframe+0x49/0xb3 Freed by task 11231: save_stack mm/kasan/common.c:72 [inline] set_track mm/kasan/common.c:80 [inline] kasan_set_free_info mm/kasan/common.c:340 [inline] __kasan_slab_free+0x12e/0x1e0 mm/kasan/common.c:479 __cache_free mm/slab.c:3426 [inline] kfree+0x10a/0x220 mm/slab.c:3757 sk_prot_free net/core/sock.c:1641 [inline] __sk_destruct+0x61d/0x740 net/core/sock.c:1725 tun_detach drivers/net/tun.c:707 [inline] tun_chr_close+0x113/0x130 drivers/net/tun.c:3412 __fput+0x2ed/0x750 fs/file_table.c:280 task_work_run+0x147/0x1d0 kernel/task_work.c:123 tracehook_notify_resume include/linux/tracehook.h:188 [inline] exit_to_usermode_loop arch/x86/entry/common.c:165 [inline] prepare_exit_to_usermode+0x48e/0x600 arch/x86/entry/common.c:196 entry_SYSCALL_64_after_hwframe+0x49/0xb3 The buggy address belongs to the object at ffff888091a7e000 which belongs to the cache kmalloc-4k of size 4096 The buggy address is located 1784 bytes inside of 4096-byte region [ffff888091a7e000, ffff888091a7f000) The buggy address belongs to the page: page:ffffea0002469f80 refcount:1 mapcount:0 mapping:000000006f6bd16f index:0x0 head:ffffea0002469f80 order:1 compound_mapcount:0 flags: 0xfffe0000010200(slab|head) raw: 00fffe0000010200 ffffea0002249d08 ffffea0002486e08 ffff8880aa402000 raw: 0000000000000000 ffff888091a7e000 0000000100000001 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff888091a7e580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888091a7e600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff888091a7e680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888091a7e700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888091a7e780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================