==================================================================
BUG: KASAN: slab-use-after-free in ucma_create_uevent+0xb60/0xbe0 drivers/infiniband/core/ucma.c:275
Read of size 8 at addr ffff888025901110 by task kworker/u32:0/12

CPU: 0 UID: 0 PID: 12 Comm: kworker/u32:0 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
Workqueue: rdma_cm cma_iboe_join_work_handler
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0x156/0x4c9 mm/kasan/report.c:482
 kasan_report+0xdf/0x1e0 mm/kasan/report.c:595
 ucma_create_uevent+0xb60/0xbe0 drivers/infiniband/core/ucma.c:275
 ucma_event_handler+0x102/0x940 drivers/infiniband/core/ucma.c:356
 cma_cm_event_handler+0x99/0x330 drivers/infiniband/core/cma.c:2181
 cma_iboe_join_work_handler+0xca/0x180 drivers/infiniband/core/cma.c:3016
 process_one_work+0x9d7/0x1920 kernel/workqueue.c:3275
 process_scheduled_works kernel/workqueue.c:3358 [inline]
 worker_thread+0x5da/0xe40 kernel/workqueue.c:3439
 kthread+0x370/0x450 kernel/kthread.c:467
 ret_from_fork+0x754/0xd80 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>

Allocated by task 6388:
 kasan_save_stack+0x30/0x50 mm/kasan/common.c:57
 kasan_save_track+0x14/0x30 mm/kasan/common.c:78
 poison_kmalloc_redzone mm/kasan/common.c:398 [inline]
 __kasan_kmalloc+0xaa/0xb0 mm/kasan/common.c:415
 kmalloc_noprof include/linux/slab.h:962 [inline]
 kzalloc_noprof include/linux/slab.h:1204 [inline]
 ucma_process_join+0x232/0xa20 drivers/infiniband/core/ucma.c:1532
 ucma_join_multicast+0xe9/0x160 drivers/infiniband/core/ucma.c:1624
 ucma_write+0x1fb/0x330 drivers/infiniband/core/ucma.c:1856
 vfs_write+0x2aa/0x1070 fs/read_write.c:686
 ksys_write+0x1f8/0x250 fs/read_write.c:740
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x106/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 6388:
 kasan_save_stack+0x30/0x50 mm/kasan/common.c:57
 kasan_save_track+0x14/0x30 mm/kasan/common.c:78
 kasan_save_free_info+0x3b/0x70 mm/kasan/generic.c:584
 poison_slab_object mm/kasan/common.c:253 [inline]
 __kasan_slab_free+0x5f/0x80 mm/kasan/common.c:285
 kasan_slab_free include/linux/kasan.h:235 [inline]
 slab_free_hook mm/slub.c:2687 [inline]
 slab_free mm/slub.c:6124 [inline]
 kfree+0x1f6/0x6b0 mm/slub.c:6442
 ucma_process_join+0x39a/0xa20 drivers/infiniband/core/ucma.c:1583
 ucma_join_multicast+0xe9/0x160 drivers/infiniband/core/ucma.c:1624
 ucma_write+0x1fb/0x330 drivers/infiniband/core/ucma.c:1856
 vfs_write+0x2aa/0x1070 fs/read_write.c:686
 ksys_write+0x1f8/0x250 fs/read_write.c:740
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x106/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff888025901100
 which belongs to the cache kmalloc-192 of size 192
The buggy address is located 16 bytes inside of
 freed 192-byte region [ffff888025901100, ffff8880259011c0)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff888025901600 pfn:0x25901
flags: 0xfff00000000200(workingset|node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000200 ffff88801b8423c0 ffffea0000b61990 ffffea0000954e50
raw: ffff888025901600 000000000010000c 00000000f5000000 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0xd2cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 1, tgid 1 (swapper/0), ts 24571229066, free_ts 24561021479
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x153/0x170 mm/page_alloc.c:1889
 prep_new_page mm/page_alloc.c:1897 [inline]
 get_page_from_freelist+0x111d/0x3140 mm/page_alloc.c:3962
 __alloc_frozen_pages_noprof+0x27c/0x2ba0 mm/page_alloc.c:5250
 alloc_slab_page mm/slub.c:3255 [inline]
 allocate_slab mm/slub.c:3444 [inline]
 new_slab+0xa6/0x6d0 mm/slub.c:3502
 refill_objects+0x26b/0x400 mm/slub.c:7134
 refill_sheaf mm/slub.c:2804 [inline]
 alloc_full_sheaf mm/slub.c:2825 [inline]
 __pcs_replace_empty_main+0x19f/0x600 mm/slub.c:4588
 alloc_from_pcs mm/slub.c:4681 [inline]
 slab_alloc_node mm/slub.c:4815 [inline]
 __kmalloc_cache_noprof+0x493/0x6f0 mm/slub.c:5334
 kmalloc_noprof include/linux/slab.h:962 [inline]
 kzalloc_noprof include/linux/slab.h:1204 [inline]
 call_usermodehelper_setup+0xaf/0x360 kernel/umh.c:362
 kobject_uevent_env+0x17c1/0x18b0 lib/kobject_uevent.c:628
 kernel_add_sysfs_param kernel/params.c:811 [inline]
 param_sysfs_builtin kernel/params.c:846 [inline]
 param_sysfs_builtin_init+0x37b/0x3f0 kernel/params.c:982
 do_one_initcall+0x11d/0x760 init/main.c:1382
 do_initcall_level init/main.c:1444 [inline]
 do_initcalls init/main.c:1460 [inline]
 do_basic_setup init/main.c:1479 [inline]
 kernel_init_freeable+0x6e5/0x7a0 init/main.c:1692
 kernel_init+0x1f/0x1e0 init/main.c:1582
 ret_from_fork+0x754/0xd80 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
page last free pid 1 tgid 1 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 __free_pages_prepare mm/page_alloc.c:1433 [inline]
 __free_frozen_pages+0x7e1/0x10d0 mm/page_alloc.c:2978
 qlink_free mm/kasan/quarantine.c:163 [inline]
 qlist_free_all+0x47/0xe0 mm/kasan/quarantine.c:179
 kasan_quarantine_reduce+0x1a0/0x1f0 mm/kasan/quarantine.c:286
 __kasan_slab_alloc+0x69/0x90 mm/kasan/common.c:350
 kasan_slab_alloc include/linux/kasan.h:253 [inline]
 slab_post_alloc_hook mm/slub.c:4501 [inline]
 slab_alloc_node mm/slub.c:4830 [inline]
 kmem_cache_alloc_noprof+0x241/0x6e0 mm/slub.c:4837
 __kernfs_new_node+0xd2/0x960 fs/kernfs/dir.c:637
 kernfs_new_node+0x11b/0x1a0 fs/kernfs/dir.c:718
 __kernfs_create_file+0x53/0x350 fs/kernfs/file.c:1057
 sysfs_add_file_mode_ns+0x207/0x3c0 fs/sysfs/file.c:313
 create_files fs/sysfs/group.c:82 [inline]
 internal_create_group+0x593/0xf40 fs/sysfs/group.c:189
 kernel_add_sysfs_param kernel/params.c:809 [inline]
 param_sysfs_builtin kernel/params.c:846 [inline]
 param_sysfs_builtin_init+0x355/0x3f0 kernel/params.c:982
 do_one_initcall+0x11d/0x760 init/main.c:1382
 do_initcall_level init/main.c:1444 [inline]
 do_initcalls init/main.c:1460 [inline]
 do_basic_setup init/main.c:1479 [inline]
 kernel_init_freeable+0x6e5/0x7a0 init/main.c:1692
 kernel_init+0x1f/0x1e0 init/main.c:1582
 ret_from_fork+0x754/0xd80 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Memory state around the buggy address:
 ffff888025901000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff888025901080: 00 00 00 00 fc fc fc fc fc fc fc fc fc fc fc fc
>ffff888025901100: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                         ^
 ffff888025901180: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
 ffff888025901200: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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