================================================================== BUG: KASAN: use-after-free in __write_once_size include/linux/compiler.h:295 [inline] BUG: KASAN: use-after-free in __hlist_del include/linux/list.h:771 [inline] BUG: KASAN: use-after-free in detach_timer kernel/time/timer.c:824 [inline] BUG: KASAN: use-after-free in detach_if_pending kernel/time/timer.c:841 [inline] BUG: KASAN: use-after-free in try_to_del_timer_sync+0x280/0x460 kernel/time/timer.c:1238 Write of size 8 at addr ffff8881e46131c0 by task syz-executor.2/549 CPU: 0 PID: 549 Comm: syz-executor.2 Not tainted 5.4.161-syzkaller-00025-g961dd91cc692 #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+0x18e/0x1de lib/dump_stack.c:118 print_address_description+0x9b/0x650 mm/kasan/report.c:384 __kasan_report+0x182/0x260 mm/kasan/report.c:516 kasan_report+0x30/0x60 mm/kasan/common.c:653 __write_once_size include/linux/compiler.h:295 [inline] __hlist_del include/linux/list.h:771 [inline] detach_timer kernel/time/timer.c:824 [inline] detach_if_pending kernel/time/timer.c:841 [inline] try_to_del_timer_sync+0x280/0x460 kernel/time/timer.c:1238 del_timer_sync+0x78/0xe0 kernel/time/timer.c:1379 tun_flow_uninit drivers/net/tun.c:1382 [inline] tun_free_netdev+0x99/0x3b0 drivers/net/tun.c:2323 netdev_run_todo+0xa3c/0xc80 net/core/dev.c:9442 tun_detach drivers/net/tun.c:751 [inline] tun_chr_close+0xc0/0xd0 drivers/net/tun.c:3517 __fput+0x27d/0x6c0 fs/file_table.c:281 task_work_run+0x186/0x1b0 kernel/task_work.c:113 exit_task_work include/linux/task_work.h:22 [inline] do_exit+0xc0a/0x2aa0 kernel/exit.c:812 do_group_exit+0x15c/0x2c0 kernel/exit.c:910 get_signal+0x151f/0x1e10 kernel/signal.c:2735 do_signal+0x3b/0x580 arch/x86/kernel/signal.c:809 exit_to_usermode_loop arch/x86/entry/common.c:159 [inline] prepare_exit_to_usermode+0x207/0x310 arch/x86/entry/common.c:194 retint_user+0x8/0x8 RIP: 0033:0x7fb921b61051 Code: Bad RIP value. RSP: 002b:0000000020000020 EFLAGS: 00010217 RAX: 0000000000000000 RBX: 00007fb921c73f60 RCX: 00007fb921b61049 RDX: 0000000020000100 RSI: 0000000020000020 RDI: 0000000040000000 RBP: 00007fb921bbb08d R08: 0000000020000f80 R09: 0000000020000f80 R10: 0000000020000180 R11: 0000000000000206 R12: 0000000000000000 R13: 00007ffd3e0ccd4f R14: 00007fb920cd7300 R15: 0000000000022000 The buggy address belongs to the page: page:ffffea00079184c0 refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 flags: 0x8000000000000000() raw: 8000000000000000 0000000000000000 ffffea0007a4f308 0000000000000000 raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000 page dumped because: kasan: bad access detected page_owner tracks the page as freed page last allocated via order 2, migratetype Unmovable, gfp_mask 0x146dc0(GFP_USER|__GFP_NOWARN|__GFP_RETRY_MAYFAIL|__GFP_COMP|__GFP_ZERO) set_page_owner include/linux/page_owner.h:31 [inline] post_alloc_hook mm/page_alloc.c:2165 [inline] prep_new_page+0x19a/0x380 mm/page_alloc.c:2171 get_page_from_freelist+0x550/0x8b0 mm/page_alloc.c:3794 __alloc_pages_nodemask+0x2d6/0x740 mm/page_alloc.c:4855 __alloc_pages include/linux/gfp.h:503 [inline] __alloc_pages_node include/linux/gfp.h:516 [inline] alloc_pages_node include/linux/gfp.h:530 [inline] kmalloc_order mm/slab_common.c:1342 [inline] kmalloc_order_trace+0x2a/0xf0 mm/slab_common.c:1358 kmalloc_large include/linux/slab.h:485 [inline] __kmalloc+0x1ae/0x2f0 mm/slub.c:3902 __kmalloc_node include/linux/slab.h:422 [inline] kmalloc_node include/linux/slab.h:599 [inline] kvmalloc_node+0x7e/0xf0 mm/util.c:564 kvmalloc include/linux/mm.h:758 [inline] kvzalloc include/linux/mm.h:766 [inline] alloc_netdev_mqs+0x85/0xc60 net/core/dev.c:9594 tun_set_iff drivers/net/tun.c:2808 [inline] __tun_chr_ioctl+0x1e36/0x4a50 drivers/net/tun.c:3143 do_vfs_ioctl+0x6fb/0x15b0 fs/ioctl.c:47 ksys_ioctl fs/ioctl.c:742 [inline] __do_sys_ioctl fs/ioctl.c:749 [inline] __se_sys_ioctl fs/ioctl.c:747 [inline] __x64_sys_ioctl+0xd4/0x110 fs/ioctl.c:747 do_syscall_64+0xcb/0x1e0 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x44/0xa9 page last free stack trace: reset_page_owner include/linux/page_owner.h:24 [inline] free_pages_prepare mm/page_alloc.c:1176 [inline] __free_pages_ok+0xbb6/0xcc0 mm/page_alloc.c:1438 free_the_page mm/page_alloc.c:4917 [inline] __free_pages+0x47/0x1e0 mm/page_alloc.c:4923 kfree+0x200/0x690 mm/slub.c:4068 device_release+0x70/0x1a0 drivers/base/core.c:1776 kobject_cleanup+0x1de/0x3c0 lib/kobject.c:708 tun_set_iff drivers/net/tun.c:2900 [inline] __tun_chr_ioctl+0x292f/0x4a50 drivers/net/tun.c:3143 do_vfs_ioctl+0x6fb/0x15b0 fs/ioctl.c:47 ksys_ioctl fs/ioctl.c:742 [inline] __do_sys_ioctl fs/ioctl.c:749 [inline] __se_sys_ioctl fs/ioctl.c:747 [inline] __x64_sys_ioctl+0xd4/0x110 fs/ioctl.c:747 do_syscall_64+0xcb/0x1e0 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x44/0xa9 Memory state around the buggy address: ffff8881e4613080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ffff8881e4613100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff >ffff8881e4613180: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ^ ffff8881e4613200: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ffff8881e4613280: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ==================================================================