================================================================== 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 ffff8801b944d3d8 by task syz-executor2/3675 CPU: 0 PID: 3675 Comm: syz-executor2 Not tainted 4.9.123-g7fa8c15 #80 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 ffff8801a5387540 ffffffff81eb9689 ffffea0006e51340 ffff8801b944d3d8 0000000000000000 ffff8801b944d3d8 0000000000000040 ffff8801a5387578 ffffffff8156c3fe ffff8801b944d3d8 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 0: 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] ip_route_output_flow+0x29/0xa0 net/ipv4/route.c:2442 ip_route_output_ports include/net/route.h:160 [inline] inet_sk_rebuild_header+0x7e9/0x1be0 net/ipv4/af_inet.c:1200 __tcp_retransmit_skb+0x23e/0x1d90 net/ipv4/tcp_output.c:2714 tcp_retransmit_skb+0x29/0x2a0 net/ipv4/tcp_output.c:2782 tcp_retransmit_timer+0x92a/0x2290 net/ipv4/tcp_timer.c:507 tcp_write_timer_handler+0x1f1/0x7a0 net/ipv4/tcp_timer.c:591 tcp_write_timer+0xc2/0x180 net/ipv4/tcp_timer.c:609 call_timer_fn+0x163/0x6e0 kernel/time/timer.c:1319 expire_timers kernel/time/timer.c:1359 [inline] __run_timers kernel/time/timer.c:1658 [inline] run_timer_softirq+0x1047/0x1590 kernel/time/timer.c:1684 __do_softirq+0x210/0x940 kernel/softirq.c:288 Freed by task 0: 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_free include/net/dst.h:434 [inline] dst_rcu_free+0x9c/0xc0 include/net/dst.h:444 __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 ffff8801b944d3c0 which belongs to the cache ip_dst_cache of size 216 The buggy address is located 24 bytes inside of 216-byte region [ffff8801b944d3c0, ffff8801b944d498) The buggy address belongs to the page: page:ffffea0006e51340 count:1 mapcount:0 mapping: (null) index:0x0 flags: 0x8000000000000080(slab) page dumped because: kasan: bad access detected Memory state around the buggy address: ffff8801b944d280: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffff8801b944d300: 00 00 00 00 00 00 00 00 00 00 00 fc fc fc fc fc >ffff8801b944d380: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb ^ ffff8801b944d400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8801b944d480: fb fb fb fc fc fc fc fc fc fc fc fc fc fc fc fc ==================================================================