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SubjectKASAN: use-after-free Read in cma_check_port
From
Hello,

syzbot found the following crash on:

HEAD commit: e3ecb83e Add linux-next specific files for 20190401
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=12e48937200000
kernel config: https://syzkaller.appspot.com/x/.config?x=db6c9f2bfeb91a99
dashboard link: https://syzkaller.appspot.com/bug?extid=70f6c187224c333bb8da
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+70f6c187224c333bb8da@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: use-after-free in cma_check_port+0x8ce/0x8f0
drivers/infiniband/core/cma.c:3354
Read of size 8 at addr ffff88809a6e7a08 by task syz-executor.2/901

CPU: 0 PID: 901 Comm: syz-executor.2 Not tainted 5.1.0-rc2-next-20190401 #15
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+0x172/0x1f0 lib/dump_stack.c:113
print_address_description.cold+0x7c/0x20d mm/kasan/report.c:187
kasan_report.cold+0x1b/0x40 mm/kasan/report.c:317
__asan_report_load8_noabort+0x14/0x20 mm/kasan/generic_report.c:132
cma_check_port+0x8ce/0x8f0 drivers/infiniband/core/cma.c:3354
cma_use_port drivers/infiniband/core/cma.c:3391 [inline]
cma_get_port drivers/infiniband/core/cma.c:3473 [inline]
rdma_bind_addr+0x19c3/0x1f80 drivers/infiniband/core/cma.c:3591
cma_bind_addr drivers/infiniband/core/cma.c:3121 [inline]
rdma_resolve_addr+0x437/0x21f0 drivers/infiniband/core/cma.c:3132
ucma_resolve_ip+0x153/0x210 drivers/infiniband/core/ucma.c:715
ucma_write+0x2da/0x3c0 drivers/infiniband/core/ucma.c:1696
__vfs_write+0x8d/0x110 fs/read_write.c:485
vfs_write+0x20c/0x580 fs/read_write.c:549
ksys_write+0xea/0x1f0 fs/read_write.c:598
__do_sys_write fs/read_write.c:610 [inline]
__se_sys_write fs/read_write.c:607 [inline]
__x64_sys_write+0x73/0xb0 fs/read_write.c:607
do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x458209
Code: ad b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7
48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff
ff 0f 83 7b b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f1cae168c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000458209
RDX: 0000000000000048 RSI: 00000000200001c0 RDI: 000000000000000b
RBP: 000000000073bfa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f1cae1696d4
R13: 00000000004ce0e8 R14: 00000000004dd828 R15: 00000000ffffffff

Allocated by task 884:
save_stack+0x45/0xd0 mm/kasan/common.c:75
set_track mm/kasan/common.c:87 [inline]
__kasan_kmalloc mm/kasan/common.c:497 [inline]
__kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:470
kasan_kmalloc+0x9/0x10 mm/kasan/common.c:511
kmem_cache_alloc_trace+0x151/0x760 mm/slab.c:3622
kmalloc include/linux/slab.h:547 [inline]
kzalloc include/linux/slab.h:742 [inline]
cma_alloc_port+0x4f/0x1a0 drivers/infiniband/core/cma.c:3241
cma_use_port drivers/infiniband/core/cma.c:3389 [inline]
cma_get_port drivers/infiniband/core/cma.c:3473 [inline]
rdma_bind_addr+0x1bc0/0x1f80 drivers/infiniband/core/cma.c:3591
cma_bind_addr drivers/infiniband/core/cma.c:3121 [inline]
rdma_resolve_addr+0x437/0x21f0 drivers/infiniband/core/cma.c:3132
ucma_resolve_ip+0x153/0x210 drivers/infiniband/core/ucma.c:715
ucma_write+0x2da/0x3c0 drivers/infiniband/core/ucma.c:1696
__vfs_write+0x8d/0x110 fs/read_write.c:485
vfs_write+0x20c/0x580 fs/read_write.c:549
ksys_write+0xea/0x1f0 fs/read_write.c:598
__do_sys_write fs/read_write.c:610 [inline]
__se_sys_write fs/read_write.c:607 [inline]
__x64_sys_write+0x73/0xb0 fs/read_write.c:607
do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 881:
save_stack+0x45/0xd0 mm/kasan/common.c:75
set_track mm/kasan/common.c:87 [inline]
__kasan_slab_free+0x102/0x150 mm/kasan/common.c:459
kasan_slab_free+0xe/0x10 mm/kasan/common.c:467
__cache_free mm/slab.c:3499 [inline]
kfree+0xcf/0x230 mm/slab.c:3822
cma_release_port drivers/infiniband/core/cma.c:1773 [inline]
rdma_destroy_id+0x7fc/0xaa0 drivers/infiniband/core/cma.c:1840
ucma_close+0x115/0x320 drivers/infiniband/core/ucma.c:1777
__fput+0x2e5/0x8d0 fs/file_table.c:278
____fput+0x16/0x20 fs/file_table.c:309
task_work_run+0x14a/0x1c0 kernel/task_work.c:113
tracehook_notify_resume include/linux/tracehook.h:188 [inline]
exit_to_usermode_loop+0x273/0x2c0 arch/x86/entry/common.c:166
prepare_exit_to_usermode arch/x86/entry/common.c:197 [inline]
syscall_return_slowpath arch/x86/entry/common.c:268 [inline]
do_syscall_64+0x52d/0x610 arch/x86/entry/common.c:293
entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff88809a6e7a00
which belongs to the cache kmalloc-32 of size 32
The buggy address is located 8 bytes inside of
32-byte region [ffff88809a6e7a00, ffff88809a6e7a20)
The buggy address belongs to the page:
page:ffffea000269b9c0 count:1 mapcount:0 mapping:ffff88812c3f01c0
index:0xffff88809a6e7fc1
flags: 0x1fffc0000000200(slab)
raw: 01fffc0000000200 ffffea0002945248 ffffea00023b0f48 ffff88812c3f01c0
raw: ffff88809a6e7fc1 ffff88809a6e7000 0000000100000039 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff88809a6e7900: 00 01 fc fc fc fc fc fc fb fb fb fb fc fc fc fc
ffff88809a6e7980: fb fb fb fb fc fc fc fc 00 00 fc fc fc fc fc fc
> ffff88809a6e7a00: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
^
ffff88809a6e7a80: 00 00 00 00 fc fc fc fc fb fb fb fb fc fc fc fc
ffff88809a6e7b00: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
==================================================================


---
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:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

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