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BUG: KASAN: use-after-free in __read_once_size include/linux/compiler.h:243 [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:240 [inline]
BUG: KASAN: use-after-free in atomic_add_unless include/linux/atomic.h:506 [inline]
BUG: KASAN: use-after-free in sk_dst_get include/net/sock.h:1696 [inline]
BUG: KASAN: use-after-free in sk_dst_check+0x372/0x3a0 net/core/sock.c:513
Read of size 4 at addr ffff8801cbbd5800 by task syz-executor5/15975

CPU: 1 PID: 15975 Comm: syz-executor5 Not tainted 4.9.132+ #51
 ffff8801a344f690 ffffffff81b371b9 ffffea00072ef540 ffff8801cbbd5800
 0000000000000000 ffff8801cbbd5800 ffff8801cbbd5800 ffff8801a344f6c8
 ffffffff81500bad ffff8801cbbd5800 0000000000000004 0000000000000000
Call Trace:
 [<ffffffff81b371b9>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81b371b9>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81500bad>] print_address_description+0x6c/0x234 mm/kasan/report.c:256
 [<ffffffff81500fb7>] kasan_report_error mm/kasan/report.c:355 [inline]
 [<ffffffff81500fb7>] kasan_report.cold.6+0x242/0x2fe mm/kasan/report.c:412
 [<ffffffff814f31a4>] __asan_report_load4_noabort+0x14/0x20 mm/kasan/report.c:432
 [<ffffffff82297782>] __read_once_size include/linux/compiler.h:243 [inline]
 [<ffffffff82297782>] atomic_read arch/x86/include/asm/atomic.h:26 [inline]
 [<ffffffff82297782>] __atomic_add_unless arch/x86/include/asm/atomic.h:240 [inline]
 [<ffffffff82297782>] atomic_add_unless include/linux/atomic.h:506 [inline]
 [<ffffffff82297782>] sk_dst_get include/net/sock.h:1696 [inline]
 [<ffffffff82297782>] sk_dst_check+0x372/0x3a0 net/core/sock.c:513
 [<ffffffff82559c1a>] udp_sendmsg+0x107a/0x1c50 net/ipv4/udp.c:1010
 [<ffffffff82583543>] inet_sendmsg+0x203/0x4d0 net/ipv4/af_inet.c:770
 [<ffffffff8228e04b>] sock_sendmsg_nosec net/socket.c:648 [inline]
 [<ffffffff8228e04b>] sock_sendmsg+0xbb/0x110 net/socket.c:658
 [<ffffffff8228faaa>] ___sys_sendmsg+0x47a/0x840 net/socket.c:1982
 [<ffffffff82292fb1>] __sys_sendmmsg+0x161/0x3d0 net/socket.c:2072
 [<ffffffff82293255>] SYSC_sendmmsg net/socket.c:2103 [inline]
 [<ffffffff82293255>] SyS_sendmmsg+0x35/0x60 net/socket.c:2098
 [<ffffffff810056ef>] do_syscall_64+0x19f/0x550 arch/x86/entry/common.c:285
 [<ffffffff82803953>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb

Allocated by task 15975:
 save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:57
 save_stack mm/kasan/kasan.c:505 [inline]
 set_track mm/kasan/kasan.c:517 [inline]
 kasan_kmalloc.part.1+0x62/0xf0 mm/kasan/kasan.c:609
 kasan_kmalloc+0xaf/0xc0 mm/kasan/kasan.c:594
 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+0xd5/0x2b0 mm/slub.c:2728
 dst_alloc+0xb5/0x1a0 net/core/dst.c:210
 ipv4_blackhole_route+0x30/0x700 net/ipv4/route.c:2407
 make_blackhole net/xfrm/xfrm_policy.c:2189 [inline]
 xfrm_lookup_route+0xf5/0x140 net/xfrm/xfrm_policy.c:2359
 ip_route_output_flow+0x90/0xa0 net/ipv4/route.c:2448
 udp_sendmsg+0x13cd/0x1c50 net/ipv4/udp.c:1025
 inet_sendmsg+0x203/0x4d0 net/ipv4/af_inet.c:770
 sock_sendmsg_nosec net/socket.c:648 [inline]
 sock_sendmsg+0xbb/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+0x19f/0x550 arch/x86/entry/common.c:285
 entry_SYSCALL_64_after_swapgs+0x5d/0xdb

Freed by task 5202:
 save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:57
 save_stack mm/kasan/kasan.c:505 [inline]
 set_track mm/kasan/kasan.c:517 [inline]
 kasan_slab_free+0xac/0x190 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+0x277/0x350 net/core/dst.c:270
 dst_gc_task+0x1a9/0x510 net/core/dst.c:89
 process_one_work+0x831/0x1530 kernel/workqueue.c:2092
 worker_thread+0xd6/0x1140 kernel/workqueue.c:2226
 kthread+0x26d/0x300 kernel/kthread.c:211
 ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:373

The buggy address belongs to the object at ffff8801cbbd5780
 which belongs to the cache ip_dst_cache of size 216
The buggy address is located 128 bytes inside of
 216-byte region [ffff8801cbbd5780, ffff8801cbbd5858)
The buggy address belongs to the page:
page:ffffea00072ef540 count:1 mapcount:0 mapping:          (null) index:0x0
flags: 0x4000000000000080(slab)
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801cbbd5700: 00 00 00 fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8801cbbd5780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8801cbbd5800: fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc fc
                   ^
 ffff8801cbbd5880: fc fc fc fc fc fc fc fc 00 00 00 00 00 00 00 00
 ffff8801cbbd5900: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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