================================================================== BUG: KASAN: use-after-free in ip6_dst_idev include/net/ip6_fib.h:141 [inline] BUG: KASAN: use-after-free in ip6_xmit+0x1838/0x1b80 net/ipv6/ip6_output.c:254 Read of size 8 at addr ffff8801cf75e3d8 by task syz-executor3/14948 CPU: 1 PID: 14948 Comm: syz-executor3 Not tainted 4.9.124-g09eb2ba #83 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 ffff8801cc757540 ffffffff81eb95e9 ffffea00073dd780 ffff8801cf75e3d8 0000000000000000 ffff8801cf75e3d8 0000000000000040 ffff8801cc757578 ffffffff8156c35e ffff8801cf75e3d8 0000000000000008 0000000000000000 Call Trace: [] __dump_stack lib/dump_stack.c:15 [inline] [] dump_stack+0xc1/0x128 lib/dump_stack.c:51 [] print_address_description+0x6c/0x234 mm/kasan/report.c:256 [] kasan_report_error mm/kasan/report.c:355 [inline] [] kasan_report.cold.6+0x242/0x2fe mm/kasan/report.c:412 [] __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433 [] ip6_dst_idev include/net/ip6_fib.h:141 [inline] [] ip6_xmit+0x1838/0x1b80 net/ipv6/ip6_output.c:254 [] inet6_csk_xmit+0x27c/0x4d0 net/ipv6/inet6_connection_sock.c:178 [] l2tp_xmit_core net/l2tp/l2tp_core.c:1178 [inline] [] l2tp_xmit_skb+0xc45/0xf30 net/l2tp/l2tp_core.c:1273 [] pppol2tp_sendmsg+0x4e0/0x790 net/l2tp/l2tp_ppp.c:339 [] sock_sendmsg_nosec net/socket.c:648 [inline] [] sock_sendmsg+0xcc/0x110 net/socket.c:658 [] ___sys_sendmsg+0x47a/0x840 net/socket.c:1982 [] __sys_sendmmsg+0x161/0x3d0 net/socket.c:2072 [] SYSC_sendmmsg net/socket.c:2103 [inline] [] SyS_sendmmsg+0x35/0x60 net/socket.c:2098 [] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282 [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb Allocated by task 12851: 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+0xc7/0xe0 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+0xbe/0x290 mm/slub.c:2728 dst_alloc+0xb5/0x1a0 net/core/dst.c:210 rt_dst_alloc+0x78/0x430 net/ipv4/route.c:1486 __mkroute_output net/ipv4/route.c:2145 [inline] __ip_route_output_key_hash+0x9ac/0x23c0 net/ipv4/route.c:2355 __ip_route_output_key include/net/route.h:123 [inline] __xfrm4_dst_lookup net/ipv4/xfrm4_policy.c:40 [inline] xfrm4_get_saddr+0xec/0x1b0 net/ipv4/xfrm4_policy.c:64 xfrm_get_saddr net/xfrm/xfrm_policy.c:1445 [inline] xfrm_tmpl_resolve_one+0x47b/0x850 net/xfrm/xfrm_policy.c:1474 xfrm_tmpl_resolve net/xfrm/xfrm_policy.c:1527 [inline] xfrm_resolve_and_create_bundle+0x219/0x1ff0 net/xfrm/xfrm_policy.c:1875 xfrm_bundle_lookup+0x3f4/0x1220 net/xfrm/xfrm_policy.c:2119 flow_cache_lookup+0x9d9/0x1090 net/core/flow.c:273 xfrm_lookup+0x4e6/0xb70 net/xfrm/xfrm_policy.c:2259 xfrm_lookup_route+0x39/0x1b0 net/xfrm/xfrm_policy.c:2351 ip_route_output_flow+0x90/0xa0 net/ipv4/route.c:2448 ip_route_output_ports include/net/route.h:160 [inline] ip_queue_xmit+0x1231/0x1ba0 net/ipv4/ip_output.c:456 __tcp_transmit_skb+0x16af/0x2e00 net/ipv4/tcp_output.c:1041 tcp_transmit_skb net/ipv4/tcp_output.c:1057 [inline] tcp_write_xmit+0x10f1/0x4ca0 net/ipv4/tcp_output.c:2221 __tcp_push_pending_frames+0xa0/0x240 net/ipv4/tcp_output.c:2402 tcp_send_fin+0x17f/0xac0 net/ipv4/tcp_output.c:3006 tcp_close+0xd8c/0x1070 net/ipv4/tcp.c:2174 inet_release+0xff/0x1d0 net/ipv4/af_inet.c:434 __sock_release+0xd7/0x260 net/socket.c:605 sock_close+0x19/0x20 net/socket.c:1059 __fput+0x263/0x700 fs/file_table.c:208 ____fput+0x15/0x20 fs/file_table.c:244 task_work_run+0x10c/0x180 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_64+0x364/0x490 arch/x86/entry/common.c:287 entry_SYSCALL_64_after_swapgs+0x5d/0xdb Freed by task 3862: 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+0xbe/0x310 mm/slub.c:2980 dst_destroy+0x200/0x360 net/core/dst.c:270 dst_destroy_rcu+0x15/0x40 net/core/dst.c:295 __rcu_reclaim kernel/rcu/rcu.h:118 [inline] rcu_do_batch kernel/rcu/tree.c:2789 [inline] invoke_rcu_callbacks kernel/rcu/tree.c:3053 [inline] __rcu_process_callbacks kernel/rcu/tree.c:3020 [inline] rcu_process_callbacks+0x8ae/0x12b0 kernel/rcu/tree.c:3037 __do_softirq+0x210/0x940 kernel/softirq.c:288 The buggy address belongs to the object at ffff8801cf75e3c0 which belongs to the cache ip_dst_cache of size 216 The buggy address is located 24 bytes inside of 216-byte region [ffff8801cf75e3c0, ffff8801cf75e498) The buggy address belongs to the page: page:ffffea00073dd780 count:1 mapcount:0 mapping: (null) index:0x0 flags: 0x8000000000000080(slab) page dumped because: kasan: bad access detected Memory state around the buggy address: ffff8801cf75e280: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffff8801cf75e300: 00 00 00 00 00 00 00 00 00 00 00 fc fc fc fc fc >ffff8801cf75e380: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb ^ ffff8801cf75e400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8801cf75e480: fb fb fb fc fc fc fc fc fc fc fc fc fc fc fc fc ==================================================================