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BUG: KASAN: use-after-free in p9_conn_cancel+0x9eb/0xd30 net/9p/trans_fd.c:222
Read of size 8 at addr ffff88019b52b628 by task kworker/1:1/4384

CPU: 1 PID: 4384 Comm: kworker/1:1 Not tainted 4.18.0-rc5-next-20180720+ #12
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events p9_read_work
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+0x242/0x30d mm/kasan/report.c:412
 __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433
 p9_conn_cancel+0x9eb/0xd30 net/9p/trans_fd.c:222
 p9_read_work+0x568/0x1060 net/9p/trans_fd.c:401
 process_one_work+0xc73/0x1ba0 kernel/workqueue.c:2153
 worker_thread+0x189/0x13c0 kernel/workqueue.c:2296
 kthread+0x345/0x410 kernel/kthread.c:246
 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:415

Allocated by task 8538:
 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
 p9_tag_alloc net/9p/client.c:259 [inline]
 p9_client_prepare_req.part.8+0xbc/0xa00 net/9p/client.c:640
 p9_client_prepare_req net/9p/client.c:675 [inline]
 p9_client_rpc+0x242/0x1330 net/9p/client.c:675
 p9_client_version net/9p/client.c:890 [inline]
 p9_client_create+0xca4/0x1537 net/9p/client.c:974
 v9fs_session_init+0x21a/0x1a80 fs/9p/v9fs.c:400
 v9fs_mount+0x7c/0x900 fs/9p/vfs_super.c:135
 legacy_get_tree+0x131/0x460 fs/fs_context.c:674
 vfs_get_tree+0x1cb/0x5c0 fs/super.c:1743
 do_new_mount fs/namespace.c:2603 [inline]
 do_mount+0x6f2/0x1e20 fs/namespace.c:2927
 ksys_mount+0x12d/0x140 fs/namespace.c:3143
 __do_sys_mount fs/namespace.c:3157 [inline]
 __se_sys_mount fs/namespace.c:3154 [inline]
 __x64_sys_mount+0xbe/0x150 fs/namespace.c:3154
 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 8538:
 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
 p9_free_req+0xe8/0x120 net/9p/client.c:340
 p9_client_rpc+0xa8e/0x1330 net/9p/client.c:739
 p9_client_version net/9p/client.c:890 [inline]
 p9_client_create+0xca4/0x1537 net/9p/client.c:974
 v9fs_session_init+0x21a/0x1a80 fs/9p/v9fs.c:400
 v9fs_mount+0x7c/0x900 fs/9p/vfs_super.c:135
 legacy_get_tree+0x131/0x460 fs/fs_context.c:674
 vfs_get_tree+0x1cb/0x5c0 fs/super.c:1743
 do_new_mount fs/namespace.c:2603 [inline]
 do_mount+0x6f2/0x1e20 fs/namespace.c:2927
 ksys_mount+0x12d/0x140 fs/namespace.c:3143
 __do_sys_mount fs/namespace.c:3157 [inline]
 __se_sys_mount fs/namespace.c:3154 [inline]
 __x64_sys_mount+0xbe/0x150 fs/namespace.c:3154
 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 ffff88019b52b5c0
 which belongs to the cache p9_req_t of size 120
The buggy address is located 104 bytes inside of
 120-byte region [ffff88019b52b5c0, ffff88019b52b638)
The buggy address belongs to the page:
page:ffffea00066d4ac0 count:1 mapcount:0 mapping:ffff8801cce10ac0 index:0xffff88019b52b678
flags: 0x2fffc0000000200(slab)
raw: 02fffc0000000200 ffff8801ccde1738 ffffea0006bd0948 ffff8801cce10ac0
raw: ffff88019b52b678 ffff88019b52b000 0000000100000015 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88019b52b500: fc fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88019b52b580: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
>ffff88019b52b600: fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc fb
                                  ^
 ffff88019b52b680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fc fc
 ffff88019b52b700: fc fc fc fc fc fc fb fb fb fb fb fb fb fb fb fb
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