==================================================================
BUG: KASAN: use-after-free in __read_once_size include/linux/compiler.h:218 [inline]
BUG: KASAN: use-after-free in atomic_read arch/x86/include/asm/atomic.h:26 [inline]
BUG: KASAN: use-after-free in __atomic_add_unless arch/x86/include/asm/atomic.h:211 [inline]
BUG: KASAN: use-after-free in atomic_add_unless include/linux/atomic.h:437 [inline]
BUG: KASAN: use-after-free in sk_dst_get include/net/sock.h:1745 [inline]
BUG: KASAN: use-after-free in sk_dst_check+0x347/0x380 net/core/sock.c:546
Read of size 4 at addr ffff8801afa80d00 by task syz-executor.3/7410

CPU: 0 PID: 7410 Comm: syz-executor.3 Not tainted 4.4.174+ #17
 0000000000000000 1ed0102cf63b3a46 ffff8800b51cf698 ffffffff81aad1a1
 0000000000000000 ffffea0006bea000 ffff8801afa80d00 0000000000000004
 0000000000000000 ffff8800b51cf6d0 ffffffff81490120 0000000000000000
Call Trace:
 [<ffffffff81aad1a1>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81aad1a1>] dump_stack+0xc1/0x120 lib/dump_stack.c:51
 [<ffffffff81490120>] print_address_description+0x6f/0x21b mm/kasan/report.c:252
 [<ffffffff81490358>] kasan_report_error mm/kasan/report.c:351 [inline]
 [<ffffffff81490358>] kasan_report mm/kasan/report.c:408 [inline]
 [<ffffffff81490358>] kasan_report.cold+0x8c/0x2be mm/kasan/report.c:393
 [<ffffffff81484eb4>] __asan_report_load4_noabort+0x14/0x20 mm/kasan/report.c:428
 [<ffffffff821e1de7>] __read_once_size include/linux/compiler.h:218 [inline]
 [<ffffffff821e1de7>] atomic_read arch/x86/include/asm/atomic.h:26 [inline]
 [<ffffffff821e1de7>] __atomic_add_unless arch/x86/include/asm/atomic.h:211 [inline]
 [<ffffffff821e1de7>] atomic_add_unless include/linux/atomic.h:437 [inline]
 [<ffffffff821e1de7>] sk_dst_get include/net/sock.h:1745 [inline]
 [<ffffffff821e1de7>] sk_dst_check+0x347/0x380 net/core/sock.c:546
 [<ffffffff8247f61f>] udp_sendmsg+0x114f/0x1c60 net/ipv4/udp.c:1019
 [<ffffffff824a8b42>] inet_sendmsg+0x202/0x4d0 net/ipv4/af_inet.c:755
 [<ffffffff821d838e>] sock_sendmsg_nosec net/socket.c:638 [inline]
 [<ffffffff821d838e>] sock_sendmsg+0xbe/0x110 net/socket.c:648
 [<ffffffff821d9e69>] ___sys_sendmsg+0x369/0x890 net/socket.c:1975
 [<ffffffff821dd386>] __sys_sendmmsg+0x1d6/0x2e0 net/socket.c:2053
 [<ffffffff822ace22>] C_SYSC_sendmmsg net/compat.c:731 [inline]
 [<ffffffff822ace22>] compat_SyS_sendmmsg+0x32/0x40 net/compat.c:728
 [<ffffffff8100603d>] do_syscall_32_irqs_on arch/x86/entry/common.c:330 [inline]
 [<ffffffff8100603d>] do_fast_syscall_32+0x32d/0xa90 arch/x86/entry/common.c:397
 [<ffffffff8271a350>] sysenter_flags_fixed+0xd/0x1a

Allocated by task 7410:
 [<ffffffff8102e3c6>] save_stack_trace+0x26/0x50 arch/x86/kernel/stacktrace.c:63
 [<ffffffff81483f22>] save_stack mm/kasan/kasan.c:512 [inline]
 [<ffffffff81483f22>] set_track mm/kasan/kasan.c:524 [inline]
 [<ffffffff81483f22>] kasan_kmalloc.part.0+0x62/0xf0 mm/kasan/kasan.c:616
 [<ffffffff81484197>] kasan_kmalloc+0xb7/0xd0 mm/kasan/kasan.c:601
 [<ffffffff8148475f>] kasan_slab_alloc+0xf/0x20 mm/kasan/kasan.c:554
 [<ffffffff8147fe9c>] slab_post_alloc_hook mm/slub.c:1349 [inline]
 [<ffffffff8147fe9c>] slab_alloc_node mm/slub.c:2615 [inline]
 [<ffffffff8147fe9c>] slab_alloc mm/slub.c:2623 [inline]
 [<ffffffff8147fe9c>] kmem_cache_alloc+0xdc/0x2c0 mm/slub.c:2628
 [<ffffffff82258393>] dst_alloc+0xf3/0x1b0 net/core/dst.c:210
 [<ffffffff823b12c0>] ipv4_blackhole_route+0x30/0x720 net/ipv4/route.c:2396
 [<ffffffff825523f4>] make_blackhole net/xfrm/xfrm_policy.c:2161 [inline]
 [<ffffffff825523f4>] xfrm_lookup_route net/xfrm/xfrm_policy.c:2331 [inline]
 [<ffffffff825523f4>] xfrm_lookup_route+0xf4/0x140 net/xfrm/xfrm_policy.c:2322
 [<ffffffff823a5a23>] ip_route_output_flow+0x93/0xa0 net/ipv4/route.c:2437
 [<ffffffff8247fa07>] udp_sendmsg+0x1537/0x1c60 net/ipv4/udp.c:1040
 [<ffffffff824a8b42>] inet_sendmsg+0x202/0x4d0 net/ipv4/af_inet.c:755
 [<ffffffff821d838e>] sock_sendmsg_nosec net/socket.c:638 [inline]
 [<ffffffff821d838e>] sock_sendmsg+0xbe/0x110 net/socket.c:648
 [<ffffffff821d9e69>] ___sys_sendmsg+0x369/0x890 net/socket.c:1975
 [<ffffffff821dd386>] __sys_sendmmsg+0x1d6/0x2e0 net/socket.c:2053
 [<ffffffff822ace22>] C_SYSC_sendmmsg net/compat.c:731 [inline]
 [<ffffffff822ace22>] compat_SyS_sendmmsg+0x32/0x40 net/compat.c:728
 [<ffffffff8100603d>] do_syscall_32_irqs_on arch/x86/entry/common.c:330 [inline]
 [<ffffffff8100603d>] do_fast_syscall_32+0x32d/0xa90 arch/x86/entry/common.c:397
 [<ffffffff8271a350>] sysenter_flags_fixed+0xd/0x1a

Freed by task 4:
 [<ffffffff8102e3c6>] save_stack_trace+0x26/0x50 arch/x86/kernel/stacktrace.c:63
 [<ffffffff81484820>] save_stack mm/kasan/kasan.c:512 [inline]
 [<ffffffff81484820>] set_track mm/kasan/kasan.c:524 [inline]
 [<ffffffff81484820>] kasan_slab_free+0xb0/0x190 mm/kasan/kasan.c:589
 [<ffffffff8148157e>] slab_free_hook mm/slub.c:1383 [inline]
 [<ffffffff8148157e>] slab_free_freelist_hook mm/slub.c:1405 [inline]
 [<ffffffff8148157e>] slab_free mm/slub.c:2859 [inline]
 [<ffffffff8148157e>] kmem_cache_free+0xbe/0x350 mm/slub.c:2881
 [<ffffffff82256eef>] dst_destroy+0x26f/0x330 net/core/dst.c:270
 [<ffffffff8225716e>] dst_gc_task+0x1be/0x530 net/core/dst.c:89
 [<ffffffff81122c25>] process_one_work+0x825/0x1720 kernel/workqueue.c:2064
 [<ffffffff81124004>] worker_thread+0x4e4/0xf50 kernel/workqueue.c:2196
 [<ffffffff811342c3>] kthread+0x273/0x310 kernel/kthread.c:211
 [<ffffffff82718fc5>] ret_from_fork+0x55/0x80 arch/x86/entry/entry_64.S:537

The buggy address belongs to the object at ffff8801afa80c80
 which belongs to the cache ip_dst_cache of size 208
The buggy address is located 128 bytes inside of
 208-byte region [ffff8801afa80c80, ffff8801afa80d50)
The buggy address belongs to the page:
kasan: CONFIG_KASAN_INLINE enabled
kasan: GPF could be caused by NULL-ptr deref or user memory access[ 1278.971060] ------------[ cut here ]------------
WARNING: CPU: 1 PID: 2104 at kernel/sched/core.c:7941 __might_sleep+0x138/0x1a0 kernel/sched/core.c:7941()
do not call blocking ops when !TASK_RUNNING; state=1 set at [<ffffffff810de6f5>] do_wait+0x265/0xa00 kernel/exit.c:1511