syzbot

IPv6: ADDRCONF(NETDEV_CHANGE): vcan0: link becomes ready
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BUG: KASAN: slab-out-of-bounds in atomic_read include/asm-generic/atomic-instrumented.h:21 [inline]
BUG: KASAN: slab-out-of-bounds in refcount_read include/linux/refcount.h:42 [inline]
BUG: KASAN: slab-out-of-bounds in check_net include/net/net_namespace.h:236 [inline]
BUG: KASAN: slab-out-of-bounds in rds_destroy_pending net/rds/rds.h:902 [inline]
BUG: KASAN: slab-out-of-bounds in rds_cong_queue_updates+0x25d/0x5b0 net/rds/cong.c:226
Read of size 4 at addr ffff8801a0030084 by task kworker/u4:3/2129

CPU: 0 PID: 2129 Comm: kworker/u4:3 Not tainted 4.18.0-rc3+ #127
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+0x1c9/0x2b4 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:902 [inline]
 rds_cong_queue_updates+0x25d/0x5b0 net/rds/cong.c:226
 rds_recv_rcvbuf_delta.part.3+0x332/0x3e0 net/rds/recv.c:123
 rds_recv_rcvbuf_delta net/rds/recv.c:382 [inline]
 rds_recv_incoming+0x85a/0x1320 net/rds/recv.c:382
 rds_loop_xmit+0x16a/0x340 net/rds/loop.c:82
 rds_send_xmit+0x1343/0x29c0 net/rds/send.c:355
 rds_send_worker+0x153/0x300 net/rds/threads.c:199
 process_one_work+0xc73/0x1ba0 kernel/workqueue.c:2153
 worker_thread+0x189/0x13c0 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 18670:
 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
 getname_flags+0xd0/0x5a0 fs/namei.c:140
 getname fs/namei.c:211 [inline]
 user_path_create fs/namei.c:3703 [inline]
 do_symlinkat+0xe9/0x2d0 fs/namei.c:4157
 __do_sys_symlink fs/namei.c:4183 [inline]
 __se_sys_symlink fs/namei.c:4181 [inline]
 __x64_sys_symlink+0x59/0x80 fs/namei.c:4181
 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 18670:
 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
 putname+0xf2/0x130 fs/namei.c:261
 filename_create+0x2b2/0x5b0 fs/namei.c:3668
 user_path_create fs/namei.c:3703 [inline]
 do_symlinkat+0xfe/0x2d0 fs/namei.c:4157
 __do_sys_symlink fs/namei.c:4183 [inline]
 __se_sys_symlink fs/namei.c:4181 [inline]
 __x64_sys_symlink+0x59/0x80 fs/namei.c:4181
 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff8801a0030100
 which belongs to the cache names_cache of size 4096
The buggy address is located 124 bytes to the left of
 4096-byte region [ffff8801a0030100, ffff8801a0031100)
The buggy address belongs to the page:
page:ffffea0006800c00 count:1 mapcount:0 mapping:ffff8801da987dc0 index:0x0 compound_mapcount: 0
flags: 0x2fffc0000008100(slab|head)
raw: 02fffc0000008100 ffffea0006c23308 ffffea0006d49a08 ffff8801da987dc0
raw: 0000000000000000 ffff8801a0030100 0000000100000001 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801a002ff80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8801a0030000: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8801a0030080: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                   ^
 ffff8801a0030100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8801a0030180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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