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BUG: KASAN: use-after-free in __list_add_valid+0x93/0xa0 lib/list_debug.c:26
Read of size 8 at addr ffff88808c8771e0 by task syz-executor.0/9824

CPU: 1 PID: 9824 Comm: syz-executor.0 Not tainted 5.6.0-rc6-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x188/0x20d lib/dump_stack.c:118
 print_address_description.constprop.0.cold+0xd3/0x315 mm/kasan/report.c:374
 __kasan_report.cold+0x1a/0x32 mm/kasan/report.c:506
 kasan_report+0xe/0x20 mm/kasan/common.c:641
 __list_add_valid+0x93/0xa0 lib/list_debug.c:26
 __list_add include/linux/list.h:67 [inline]
 list_add_tail include/linux/list.h:100 [inline]
 cma_listen_on_all drivers/infiniband/core/cma.c:2512 [inline]
 rdma_listen+0x681/0x910 drivers/infiniband/core/cma.c:3629
 ucma_listen+0x14d/0x1c0 drivers/infiniband/core/ucma.c:1092
 ucma_write+0x285/0x350 drivers/infiniband/core/ucma.c:1684
 __vfs_write+0x76/0x100 fs/read_write.c:494
 vfs_write+0x262/0x5c0 fs/read_write.c:558
 ksys_write+0x1e8/0x250 fs/read_write.c:611
 do_syscall_32_irqs_on arch/x86/entry/common.c:337 [inline]
 do_fast_syscall_32+0x270/0xe8f arch/x86/entry/common.c:408
 entry_SYSENTER_compat+0x70/0x7f arch/x86/entry/entry_64_compat.S:139

Allocated by task 9818:
 save_stack+0x1b/0x80 mm/kasan/common.c:72
 set_track mm/kasan/common.c:80 [inline]
 __kasan_kmalloc mm/kasan/common.c:515 [inline]
 __kasan_kmalloc.constprop.0+0xbf/0xd0 mm/kasan/common.c:488
 kmem_cache_alloc_trace+0x153/0x7d0 mm/slab.c:3551
 kmalloc include/linux/slab.h:555 [inline]
 kzalloc include/linux/slab.h:669 [inline]
 __rdma_create_id+0x5b/0x850 drivers/infiniband/core/cma.c:856
 ucma_create_id+0x1cb/0x580 drivers/infiniband/core/ucma.c:501
 ucma_write+0x285/0x350 drivers/infiniband/core/ucma.c:1684
 __vfs_write+0x76/0x100 fs/read_write.c:494
 vfs_write+0x262/0x5c0 fs/read_write.c:558
 ksys_write+0x1e8/0x250 fs/read_write.c:611
 do_syscall_32_irqs_on arch/x86/entry/common.c:337 [inline]
 do_fast_syscall_32+0x270/0xe8f arch/x86/entry/common.c:408
 entry_SYSENTER_compat+0x70/0x7f arch/x86/entry/entry_64_compat.S:139

Freed by task 9817:
 save_stack+0x1b/0x80 mm/kasan/common.c:72
 set_track mm/kasan/common.c:80 [inline]
 kasan_set_free_info mm/kasan/common.c:337 [inline]
 __kasan_slab_free+0xf7/0x140 mm/kasan/common.c:476
 __cache_free mm/slab.c:3426 [inline]
 kfree+0x109/0x2b0 mm/slab.c:3757
 ucma_close+0x10b/0x300 drivers/infiniband/core/ucma.c:1762
 __fput+0x2da/0x850 fs/file_table.c:280
 task_work_run+0x13f/0x1b0 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:188 [inline]
 exit_to_usermode_loop+0x2fa/0x360 arch/x86/entry/common.c:164
 prepare_exit_to_usermode arch/x86/entry/common.c:195 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:278 [inline]
 do_syscall_32_irqs_on arch/x86/entry/common.c:352 [inline]
 do_fast_syscall_32+0xbef/0xe8f arch/x86/entry/common.c:408
 entry_SYSENTER_compat+0x70/0x7f arch/x86/entry/entry_64_compat.S:139

The buggy address belongs to the object at ffff88808c877000
 which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 480 bytes inside of
 2048-byte region [ffff88808c877000, ffff88808c877800)
The buggy address belongs to the page:
page:ffffea0002321dc0 refcount:1 mapcount:0 mapping:ffff8880aa000e00 index:0x0
flags: 0xfffe0000000200(slab)
raw: 00fffe0000000200 ffffea00021cdb48 ffffea0002602888 ffff8880aa000e00
raw: 0000000000000000 ffff88808c877000 0000000100000001 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88808c877080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88808c877100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88808c877180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                       ^
 ffff88808c877200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88808c877280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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