================================================================== BUG: KASAN: use-after-free in ip6_dst_idev include/net/ip6_fib.h:141 [inline] BUG: KASAN: use-after-free in ip6_xmit+0x1bc7/0x1bd0 net/ipv6/ip6_output.c:254 Read of size 8 at addr ffff8801d078d3d8 by task syzkaller928974/3338 CPU: 0 PID: 3338 Comm: syzkaller928974 Not tainted 4.9.77-g8788313 #25 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 ffff8801c991f620 ffffffff81d941c9 ffffea000741e340 ffff8801d078d3d8 0000000000000000 ffff8801d078d3d8 ffff8801c91c0064 ffff8801c991f658 ffffffff8153db93 ffff8801d078d3d8 0000000000000008 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:252 [] kasan_report_error mm/kasan/report.c:351 [inline] [] kasan_report+0x275/0x360 mm/kasan/report.c:408 [] __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:429 [] ip6_dst_idev include/net/ip6_fib.h:141 [inline] [] ip6_xmit+0x1bc7/0x1bd0 net/ipv6/ip6_output.c:254 [] inet6_csk_xmit+0x27d/0x4d0 net/ipv6/inet6_connection_sock.c:178 [] l2tp_xmit_core net/l2tp/l2tp_core.c:1178 [inline] [] l2tp_xmit_skb+0xcdc/0xf50 net/l2tp/l2tp_core.c:1273 [] pppol2tp_sendmsg+0x5c0/0x7a0 net/l2tp/l2tp_ppp.c:339 [] sock_sendmsg_nosec net/socket.c:635 [inline] [] sock_sendmsg+0xca/0x110 net/socket.c:645 [] ___sys_sendmsg+0x6d1/0x7e0 net/socket.c:1969 [] __sys_sendmsg+0xd6/0x190 net/socket.c:2003 [] C_SYSC_sendmsg net/compat.c:734 [inline] [] compat_SyS_sendmsg+0x2a/0x40 net/compat.c:732 [] do_syscall_32_irqs_on arch/x86/entry/common.c:322 [inline] [] do_fast_syscall_32+0x2f7/0x890 arch/x86/entry/common.c:384 [] entry_SYSENTER_compat+0x74/0x83 arch/x86/entry/entry_64_compat.S:127 Allocated by task 3317: 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 dst_alloc+0x11f/0x1a0 net/core/dst.c:210 rt_dst_alloc+0x78/0x430 net/ipv4/route.c:1475 __mkroute_output net/ipv4/route.c:2133 [inline] __ip_route_output_key_hash+0xa4e/0x23e0 net/ipv4/route.c:2343 __ip_route_output_key include/net/route.h:122 [inline] ip_route_connect include/net/route.h:289 [inline] __ip4_datagram_connect+0xa17/0x1160 net/ipv4/datagram.c:51 __ip6_datagram_connect+0x6f9/0xdf0 net/ipv6/datagram.c:157 ip6_datagram_connect+0x2f/0x50 net/ipv6/datagram.c:268 inet_dgram_connect+0x16b/0x1f0 net/ipv4/af_inet.c:549 SYSC_connect+0x1b6/0x310 net/socket.c:1562 SyS_connect+0x24/0x30 net/socket.c:1543 entry_SYSCALL_64_fastpath+0x29/0xe8 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+0xc7/0x300 mm/slub.c:2980 dst_destroy+0x1fd/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+0x898/0x1300 kernel/rcu/tree.c:3037 __do_softirq+0x206/0x951 kernel/softirq.c:284 The buggy address belongs to the object at ffff8801d078d3c0 which belongs to the cache ip_dst_cache of size 216 The buggy address is located 24 bytes inside of 216-byte region [ffff8801d078d3c0, ffff8801d078d498) The buggy address belongs to the page: page:ffffea000741e340 count:1 mapcount:0 mapping: (null) index:0x0 flags: 0x8000000000000080(slab) page dumped because: kasan: bad access detected Memory state around the buggy address: ffff8801d078d280: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffff8801d078d300: 00 00 00 00 00 00 00 00 00 00 00 fc fc fc fc fc >ffff8801d078d380: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb ^ ffff8801d078d400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8801d078d480: fb fb fb fc fc fc fc fc fc fc fc fc fc fc fc fc ==================================================================