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SubjectKASAN: use-after-free Read in addr_handler (2)
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Hello,

syzbot found the following crash on:

HEAD commit: 7ae77150 Merge tag 'powerpc-5.8-1' of git://git.kernel.org..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=16c0d3a6100000
kernel config: https://syzkaller.appspot.com/x/.config?x=d195fe572fb15312
dashboard link: https://syzkaller.appspot.com/bug?extid=a929647172775e335941
compiler: gcc (GCC) 9.0.0 20181231 (experimental)

Unfortunately, I don't have any reproducer for this crash yet.

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+a929647172775e335941@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: use-after-free in __mutex_lock_common kernel/locking/mutex.c:938 [inline]
BUG: KASAN: use-after-free in __mutex_lock+0x1033/0x13c0 kernel/locking/mutex.c:1103
Read of size 8 at addr ffff888088ec33b0 by task kworker/u4:5/14014

CPU: 1 PID: 14014 Comm: kworker/u4:5 Not tainted 5.7.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: ib_addr process_one_req
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+0xd3/0x413 mm/kasan/report.c:383
__kasan_report mm/kasan/report.c:513 [inline]
kasan_report.cold+0x1f/0x37 mm/kasan/report.c:530
__mutex_lock_common kernel/locking/mutex.c:938 [inline]
__mutex_lock+0x1033/0x13c0 kernel/locking/mutex.c:1103
addr_handler+0xa0/0x340 drivers/infiniband/core/cma.c:3100
process_one_req+0xfa/0x680 drivers/infiniband/core/addr.c:643
process_one_work+0x965/0x16a0 kernel/workqueue.c:2268
worker_thread+0x96/0xe20 kernel/workqueue.c:2414
kthread+0x388/0x470 kernel/kthread.c:268
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:351

Allocated by task 31499:
save_stack+0x1b/0x40 mm/kasan/common.c:48
set_track mm/kasan/common.c:56 [inline]
__kasan_kmalloc mm/kasan/common.c:494 [inline]
__kasan_kmalloc.constprop.0+0xbf/0xd0 mm/kasan/common.c:467
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:861
ucma_create_id+0x1d1/0x590 drivers/infiniband/core/ucma.c:503
ucma_write+0x285/0x350 drivers/infiniband/core/ucma.c:1729
__vfs_write+0x76/0x100 fs/read_write.c:495
vfs_write+0x268/0x5d0 fs/read_write.c:559
ksys_write+0x1ee/0x250 fs/read_write.c:612
do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:295
entry_SYSCALL_64_after_hwframe+0x49/0xb3

Freed by task 31496:
save_stack+0x1b/0x40 mm/kasan/common.c:48
set_track mm/kasan/common.c:56 [inline]
kasan_set_free_info mm/kasan/common.c:316 [inline]
__kasan_slab_free+0xf7/0x140 mm/kasan/common.c:455
__cache_free mm/slab.c:3426 [inline]
kfree+0x109/0x2b0 mm/slab.c:3757
ucma_close+0x111/0x300 drivers/infiniband/core/ucma.c:1807
__fput+0x33e/0x880 fs/file_table.c:281
task_work_run+0xf4/0x1b0 kernel/task_work.c:123
tracehook_notify_resume include/linux/tracehook.h:188 [inline]
exit_to_usermode_loop+0x2fa/0x360 arch/x86/entry/common.c:165
prepare_exit_to_usermode arch/x86/entry/common.c:196 [inline]
syscall_return_slowpath arch/x86/entry/common.c:279 [inline]
do_syscall_64+0x6b1/0x7d0 arch/x86/entry/common.c:305
entry_SYSCALL_64_after_hwframe+0x49/0xb3

The buggy address belongs to the object at ffff888088ec3000
which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 944 bytes inside of
2048-byte region [ffff888088ec3000, ffff888088ec3800)
The buggy address belongs to the page:
page:ffffea000223b0c0 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0
flags: 0xfffe0000000200(slab)
raw: 00fffe0000000200 ffffea000299f588 ffffea000263d0c8 ffff8880aa000e00
raw: 0000000000000000 ffff888088ec3000 0000000100000001 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff888088ec3280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888088ec3300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888088ec3380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff888088ec3400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888088ec3480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


---
This bug is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@googlegroups.com.

syzbot will keep track of this bug report. See:
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