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BUG: KASAN: use-after-free in __list_add_valid+0xc6/0xd0 lib/list_debug.c:26
Read of size 8 at addr ffff8801d6e0c5c0 by task syz-executor2/28260

CPU: 1 PID: 28260 Comm: syz-executor2 Not tainted 4.16.0-rc5+ #357
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x194/0x24d lib/dump_stack.c:53
 print_address_description+0x73/0x250 mm/kasan/report.c:256
 kasan_report_error mm/kasan/report.c:354 [inline]
 kasan_report+0x23c/0x360 mm/kasan/report.c:412
 __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433
 __list_add_valid+0xc6/0xd0 lib/list_debug.c:26
 __list_add include/linux/list.h:60 [inline]
 list_add_tail include/linux/list.h:93 [inline]
 ucma_alloc_ctx+0x3f3/0x610 drivers/infiniband/core/ucma.c:204
 ucma_create_id+0x205/0x620 drivers/infiniband/core/ucma.c:473
 ucma_write+0x2d6/0x3d0 drivers/infiniband/core/ucma.c:1633
 __vfs_write+0xef/0x970 fs/read_write.c:480
 vfs_write+0x189/0x510 fs/read_write.c:544
 SYSC_write fs/read_write.c:589 [inline]
 SyS_write+0xef/0x220 fs/read_write.c:581
 do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
audit_log_start: 3517 callbacks suppressed
audit: audit_backlog=65 > audit_backlog_limit=64
RIP: 0033:0x453e69
RSP: 002b:00007f556fe20c68 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f556fe216d4 RCX: 0000000000453e69
RDX: 0000000000000020 RSI: 0000000020000080 RDI: 0000000000000013
RBP: 000000000072c010 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
audit: audit_lost=14091 audit_rate_limit=0 audit_backlog_limit=64
R13: 0000000000000672 R14: 00000000006f9b50 R15: 0000000000000002

audit: backlog limit exceeded
Allocated by task 28250:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_kmalloc+0xad/0xe0 mm/kasan/kasan.c:552
 kmem_cache_alloc_trace+0x136/0x740 mm/slab.c:3607
audit: audit_backlog=65 > audit_backlog_limit=64
 kmalloc include/linux/slab.h:512 [inline]
 kzalloc include/linux/slab.h:701 [inline]
 ucma_alloc_ctx+0xce/0x610 drivers/infiniband/core/ucma.c:188
 ucma_create_id+0x205/0x620 drivers/infiniband/core/ucma.c:473
 ucma_write+0x2d6/0x3d0 drivers/infiniband/core/ucma.c:1633
 __vfs_write+0xef/0x970 fs/read_write.c:480
 vfs_write+0x189/0x510 fs/read_write.c:544
 SYSC_write fs/read_write.c:589 [inline]
 SyS_write+0xef/0x220 fs/read_write.c:581
 do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x42/0xb7

Freed by task 28250:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 __kasan_slab_free+0x11a/0x170 mm/kasan/kasan.c:520
 kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:527
 __cache_free mm/slab.c:3485 [inline]
 kfree+0xd9/0x260 mm/slab.c:3800
 ucma_create_id+0x45b/0x620 drivers/infiniband/core/ucma.c:500
 ucma_write+0x2d6/0x3d0 drivers/infiniband/core/ucma.c:1633
 __vfs_write+0xef/0x970 fs/read_write.c:480
 vfs_write+0x189/0x510 fs/read_write.c:544
 SYSC_write fs/read_write.c:589 [inline]
 SyS_write+0xef/0x220 fs/read_write.c:581
 do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x42/0xb7

The buggy address belongs to the object at ffff8801d6e0c540
 which belongs to the cache kmalloc-256 of size 256
The buggy address is located 128 bytes inside of
 256-byte region [ffff8801d6e0c540, ffff8801d6e0c640)
The buggy address belongs to the page:
page:ffffea00075b8300 count:1 mapcount:0 mapping:ffff8801d6e0c040 index:0x0
flags: 0x2fffc0000000100(slab)
raw: 02fffc0000000100 ffff8801d6e0c040 0000000000000000 000000010000000c
raw: ffffea0006c07860 ffffea00072adae0 ffff8801dac007c0 0000000000000000
page dumped because: kasan: bad access detected
audit: audit_lost=14092 audit_rate_limit=0 audit_backlog_limit=64

Memory state around the buggy address:
 ffff8801d6e0c480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8801d6e0c500: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
>ffff8801d6e0c580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                           ^
 ffff8801d6e0c600: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
 ffff8801d6e0c680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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