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BUG: KASAN: use-after-free in atomic_read include/asm-generic/atomic-instrumented.h:21 [inline]
BUG: KASAN: use-after-free in refcount_read include/linux/refcount.h:42 [inline]
BUG: KASAN: use-after-free in check_net include/net/net_namespace.h:236 [inline]
BUG: KASAN: use-after-free in rds_destroy_pending net/rds/rds.h:897 [inline]
BUG: KASAN: use-after-free in rds_cong_queue_updates+0x255/0x590 net/rds/cong.c:226
Read of size 4 at addr ffff8801931f4104 by task kworker/u4:6/6645

CPU: 0 PID: 6645 Comm: kworker/u4:6 Not tainted 4.17.0+ #84
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: krdsd rds_send_worker
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1b9/0x294 lib/dump_stack.c:113
 print_address_description+0x6c/0x20b mm/kasan/report.c:256
 kasan_report_error mm/kasan/report.c:354 [inline]
 kasan_report.cold.7+0x242/0x2fe mm/kasan/report.c:412
 check_memory_region_inline mm/kasan/kasan.c:260 [inline]
 check_memory_region+0x13e/0x1b0 mm/kasan/kasan.c:267
 kasan_check_read+0x11/0x20 mm/kasan/kasan.c:272
 atomic_read include/asm-generic/atomic-instrumented.h:21 [inline]
 refcount_read include/linux/refcount.h:42 [inline]
 check_net include/net/net_namespace.h:236 [inline]
 rds_destroy_pending net/rds/rds.h:897 [inline]
 rds_cong_queue_updates+0x255/0x590 net/rds/cong.c:226
 rds_recv_rcvbuf_delta.part.3+0x2b9/0x350 net/rds/recv.c:118
 rds_recv_rcvbuf_delta net/rds/recv.c:377 [inline]
 rds_recv_incoming+0x83f/0x1300 net/rds/recv.c:377
 rds_loop_xmit+0x16a/0x340 net/rds/loop.c:82
 rds_send_xmit+0x131b/0x2990 net/rds/send.c:355
 rds_send_worker+0x142/0x2e0 net/rds/threads.c:199
 process_one_work+0xc64/0x1b70 kernel/workqueue.c:2153
 worker_thread+0x181/0x13a0 kernel/workqueue.c:2296
 kthread+0x345/0x410 kernel/kthread.c:240
 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:412

Allocated by task 16770:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:448
 set_track mm/kasan/kasan.c:460 [inline]
 kasan_kmalloc+0xc4/0xe0 mm/kasan/kasan.c:553
 kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:490
 kmem_cache_alloc+0x12e/0x760 mm/slab.c:3554
 kmem_cache_zalloc include/linux/slab.h:696 [inline]
 net_alloc net/core/net_namespace.c:383 [inline]
 copy_net_ns+0x159/0x4c0 net/core/net_namespace.c:423
 create_new_namespaces+0x69d/0x8f0 kernel/nsproxy.c:107
 unshare_nsproxy_namespaces+0xc3/0x1f0 kernel/nsproxy.c:206
 ksys_unshare+0x708/0xf90 kernel/fork.c:2411
 __do_sys_unshare kernel/fork.c:2479 [inline]
 __se_sys_unshare kernel/fork.c:2477 [inline]
 __x64_sys_unshare+0x31/0x40 kernel/fork.c:2477
 do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 6642:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:448
 set_track mm/kasan/kasan.c:460 [inline]
 __kasan_slab_free+0x11a/0x170 mm/kasan/kasan.c:521
 kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528
 __cache_free mm/slab.c:3498 [inline]
 kmem_cache_free+0x86/0x2d0 mm/slab.c:3756
 net_free net/core/net_namespace.c:399 [inline]
 net_drop_ns.part.14+0x11a/0x130 net/core/net_namespace.c:406
 net_drop_ns net/core/net_namespace.c:405 [inline]
 cleanup_net+0x6a1/0xb20 net/core/net_namespace.c:541
 process_one_work+0xc64/0x1b70 kernel/workqueue.c:2153
 worker_thread+0x181/0x13a0 kernel/workqueue.c:2296
 kthread+0x345/0x410 kernel/kthread.c:240
 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:412

The buggy address belongs to the object at ffff8801931f4100
 which belongs to the cache net_namespace(113:syz0) of size 8896
The buggy address is located 4 bytes inside of
 8896-byte region [ffff8801931f4100, ffff8801931f63c0)
The buggy address belongs to the page:
page:ffffea00064c7d00 count:1 mapcount:0 mapping:ffff88018d389480 index:0x0 compound_mapcount: 0
flags: 0x2fffc0000008100(slab|head)
raw: 02fffc0000008100 ffff8801ce9e0e48 ffffea0006455708 ffff88018d389480
raw: 0000000000000000 ffff8801931f4100 0000000100000001 ffff88019a624e00
page dumped because: kasan: bad access detected
page->mem_cgroup:ffff88019a624e00

Memory state around the buggy address:
 ffff8801931f4000: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8801931f4080: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8801931f4100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                   ^
 ffff8801931f4180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8801931f4200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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