audit: type=1400 audit(1521955074.986:41): avc: denied { ioctl } for pid=8752 comm="syz-executor6" path="socket:[21836]" dev="sockfs" ino=21836 ioctlcmd=0x8903 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=netlink_generic_socket permissive=1 ================================================================== BUG: KASAN: use-after-free in inet_shutdown+0x2d4/0x350 net/ipv4/af_inet.c:824 Read of size 4 at addr ffff8801d9c54880 by task syz-executor7/8746 CPU: 0 PID: 8746 Comm: syz-executor7 Not tainted 4.9.89-gf152ce1 #5 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 ffff8801b41afb78 ffffffff81d93609 ffffea0007671500 ffff8801d9c54880 0000000000000000 ffff8801d9c54880 ffff8801b41051d8 ffff8801b41afbb0 ffffffff8153be93 ffff8801d9c54880 0000000000000004 0000000000000000 Call Trace: [] __dump_stack lib/dump_stack.c:15 [inline] [] dump_stack+0xc1/0x128 lib/dump_stack.c:51 [] print_address_description+0x73/0x280 mm/kasan/report.c:256 [] kasan_report_error mm/kasan/report.c:355 [inline] [] kasan_report+0x255/0x380 mm/kasan/report.c:412 [] __asan_report_load4_noabort+0x14/0x20 mm/kasan/report.c:432 [] inet_shutdown+0x2d4/0x350 net/ipv4/af_inet.c:824 [] pppol2tp_session_close+0xa0/0xe0 net/l2tp/l2tp_ppp.c:441 [] l2tp_tunnel_closeall+0x21f/0x3a0 net/l2tp/l2tp_core.c:1368 [] l2tp_udp_encap_destroy+0x87/0xe0 net/l2tp/l2tp_core.c:1394 [] udpv6_destroy_sock+0xb1/0xd0 net/ipv6/udp.c:1336 [] sk_common_release+0x6b/0x2f0 net/core/sock.c:2727 [] udp_lib_close+0x15/0x20 include/net/udp.h:203 [] inet_release+0xfa/0x1d0 net/ipv4/af_inet.c:434 [] inet6_release+0x50/0x70 net/ipv6/af_inet6.c:440 [] sock_release+0x8d/0x1e0 net/socket.c:599 [] sock_close+0x16/0x20 net/socket.c:1046 [] __fput+0x28c/0x6e0 fs/file_table.c:208 [] ____fput+0x15/0x20 fs/file_table.c:244 [] task_work_run+0x115/0x190 kernel/task_work.c:116 [] tracehook_notify_resume include/linux/tracehook.h:191 [inline] [] exit_to_usermode_loop+0xfc/0x120 arch/x86/entry/common.c:161 [] prepare_exit_to_usermode arch/x86/entry/common.c:191 [inline] [] syscall_return_slowpath arch/x86/entry/common.c:260 [inline] [] do_syscall_32_irqs_on arch/x86/entry/common.c:331 [inline] [] do_fast_syscall_32+0x5c1/0x870 arch/x86/entry/common.c:387 [] entry_SYSENTER_compat+0x90/0xa2 arch/x86/entry/entry_64_compat.S:137 Allocated by task 8758: save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:57 save_stack+0x43/0xd0 mm/kasan/kasan.c:505 set_track mm/kasan/kasan.c:517 [inline] kasan_kmalloc+0xad/0xe0 mm/kasan/kasan.c:609 kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:547 slab_post_alloc_hook mm/slab.h:417 [inline] slab_alloc_node mm/slub.c:2715 [inline] slab_alloc mm/slub.c:2723 [inline] kmem_cache_alloc+0xba/0x290 mm/slub.c:2728 sock_alloc_inode+0x1d/0x250 net/socket.c:250 alloc_inode+0x65/0x180 fs/inode.c:207 new_inode_pseudo+0x17/0xe0 fs/inode.c:890 sock_alloc+0x41/0x270 net/socket.c:567 __sock_create+0xa5/0x640 net/socket.c:1146 sock_create net/socket.c:1222 [inline] SYSC_socket net/socket.c:1252 [inline] SyS_socket+0xf0/0x1b0 net/socket.c:1232 do_syscall_32_irqs_on arch/x86/entry/common.c:325 [inline] do_fast_syscall_32+0x2f5/0x870 arch/x86/entry/common.c:387 entry_SYSENTER_compat+0x90/0xa2 arch/x86/entry/entry_64_compat.S:137 Freed by task 8758: save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:57 save_stack+0x43/0xd0 mm/kasan/kasan.c:505 set_track mm/kasan/kasan.c:517 [inline] kasan_slab_free+0x72/0xc0 mm/kasan/kasan.c:582 slab_free_hook mm/slub.c:1355 [inline] slab_free_freelist_hook mm/slub.c:1377 [inline] slab_free mm/slub.c:2958 [inline] kmem_cache_free+0xc7/0x300 mm/slub.c:2980 sock_destroy_inode+0x56/0x70 net/socket.c:280 destroy_inode+0xc3/0x120 fs/inode.c:264 evict+0x329/0x4f0 fs/inode.c:570 iput_final fs/inode.c:1516 [inline] iput+0x47b/0x900 fs/inode.c:1543 dentry_unlink_inode+0x470/0x570 fs/dcache.c:370 __dentry_kill+0x25b/0x480 fs/dcache.c:565 dentry_kill fs/dcache.c:606 [inline] dput.part.23+0x680/0x7b0 fs/dcache.c:823 dput+0x1f/0x30 fs/dcache.c:785 __fput+0x46a/0x6e0 fs/file_table.c:226 ____fput+0x15/0x20 fs/file_table.c:244 task_work_run+0x115/0x190 kernel/task_work.c:116 tracehook_notify_resume include/linux/tracehook.h:191 [inline] exit_to_usermode_loop+0xfc/0x120 arch/x86/entry/common.c:161 prepare_exit_to_usermode arch/x86/entry/common.c:191 [inline] syscall_return_slowpath arch/x86/entry/common.c:260 [inline] do_syscall_32_irqs_on arch/x86/entry/common.c:331 [inline] do_fast_syscall_32+0x5c1/0x870 arch/x86/entry/common.c:387 entry_SYSENTER_compat+0x90/0xa2 arch/x86/entry/entry_64_compat.S:137 The buggy address belongs to the object at ffff8801d9c54880 which belongs to the cache sock_inode_cache of size 944 The buggy address is located 0 bytes inside of 944-byte region [ffff8801d9c54880, ffff8801d9c54c30) The buggy address belongs to the page: page:ffffea0007671500 count:1 mapcount:0 mapping: (null) index:0x0 compound_mapcount: 0 flags: 0x8000000000004080(slab|head) page dumped because: kasan: bad access detected Memory state around the buggy address: ffff8801d9c54780: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 fc fc ffff8801d9c54800: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff8801d9c54880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff8801d9c54900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8801d9c54980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================