linux-toradex.git/drivers/infiniband/core, branch v4.16-rc3

RDMA/uverbs: Fix kernel panic while using XRC_TGT QP type

2018-02-21T18:52:19+00:00

Attempt to modify XRC_TGT QP type from the user space (ibv_xsrq_pingpong
invocation) will trigger the following kernel panic. It is caused by the
fact that such QPs missed uobject initialization.

[   17.408845] BUG: unable to handle kernel NULL pointer dereference at 0000000000000048
[   17.412645] IP: rdma_lookup_put_uobject+0x9/0x50
[   17.416567] PGD 0 P4D 0
[   17.419262] Oops: 0000 [#1] SMP PTI
[   17.422915] CPU: 0 PID: 455 Comm: ibv_xsrq_pingpo Not tainted 4.16.0-rc1+ #86
[   17.424765] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.7.5-0-ge51488c-20140602_164612-nilsson.home.kraxel.org 04/01/2014
[   17.427399] RIP: 0010:rdma_lookup_put_uobject+0x9/0x50
[   17.428445] RSP: 0018:ffffb8c7401e7c90 EFLAGS: 00010246
[   17.429543] RAX: 0000000000000000 RBX: ffffb8c7401e7cf8 RCX: 0000000000000000
[   17.432426] RDX: 0000000000000001 RSI: 0000000000000000 RDI: 0000000000000000
[   17.437448] RBP: 0000000000000000 R08: 00000000000218f0 R09: ffffffff8ebc4cac
[   17.440223] R10: fffff6038052cd80 R11: ffff967694b36400 R12: ffff96769391f800
[   17.442184] R13: ffffb8c7401e7cd8 R14: 0000000000000000 R15: ffff967699f60000
[   17.443971] FS:  00007fc29207d700(0000) GS:ffff96769fc00000(0000) knlGS:0000000000000000
[   17.446623] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   17.448059] CR2: 0000000000000048 CR3: 000000001397a000 CR4: 00000000000006b0
[   17.449677] Call Trace:
[   17.450247]  modify_qp.isra.20+0x219/0x2f0
[   17.451151]  ib_uverbs_modify_qp+0x90/0xe0
[   17.452126]  ib_uverbs_write+0x1d2/0x3c0
[   17.453897]  ? __handle_mm_fault+0x93c/0xe40
[   17.454938]  __vfs_write+0x36/0x180
[   17.455875]  vfs_write+0xad/0x1e0
[   17.456766]  SyS_write+0x52/0xc0
[   17.457632]  do_syscall_64+0x75/0x180
[   17.458631]  entry_SYSCALL_64_after_hwframe+0x21/0x86
[   17.460004] RIP: 0033:0x7fc29198f5a0
[   17.460982] RSP: 002b:00007ffccc71f018 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
[   17.463043] RAX: ffffffffffffffda RBX: 0000000000000078 RCX: 00007fc29198f5a0
[   17.464581] RDX: 0000000000000078 RSI: 00007ffccc71f050 RDI: 0000000000000003
[   17.466148] RBP: 0000000000000000 R08: 0000000000000078 R09: 00007ffccc71f050
[   17.467750] R10: 000055b6cf87c248 R11: 0000000000000246 R12: 00007ffccc71f300
[   17.469541] R13: 000055b6cf8733a0 R14: 0000000000000000 R15: 0000000000000000
[   17.471151] Code: 00 00 0f 1f 44 00 00 48 8b 47 48 48 8b 00 48 8b 40 10 e9 0b 8b 68 00 90 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 55 53 89 f5 <48> 8b 47 48 48 89 fb 40 0f b6 f6 48 8b 00 48 8b 40 20 e8 e0 8a
[   17.475185] RIP: rdma_lookup_put_uobject+0x9/0x50 RSP: ffffb8c7401e7c90
[   17.476841] CR2: 0000000000000048
[   17.477764] ---[ end trace 1dbcc5354071a712 ]---
[   17.478880] Kernel panic - not syncing: Fatal exception
[   17.480277] Kernel Offset: 0xd000000 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffffbfffffff)

Fixes: 2f08ee363fe0 ("RDMA/restrack: don't use uaccess_kernel()")
Signed-off-by: Leon Romanovsky 
Signed-off-by: Doug Ledford

RDMA/restrack: don't use uaccess_kernel()

2018-02-16T17:18:11+00:00

uaccess_kernel() isn't sufficient to determine if an rdma resource is
user-mode or not.  For example, resources allocated in the add_one()
function of an ib_client get falsely labeled as user mode, when they
are kernel mode allocations.  EG: mad qps.

The result is that these qps are skipped over during a nldev query
because of an erroneous namespace mismatch.

So now we determine if the resource is user-mode by looking at the object
struct's uobject or similar pointer to know if it was allocated for user
mode applications.

Fixes: 02d8883f520e ("RDMA/restrack: Add general infrastructure to track RDMA resources")
Signed-off-by: Steve Wise 
Signed-off-by: Jason Gunthorpe

RDMA/verbs: Check existence of function prior to accessing it

2018-02-16T16:18:55+00:00

Update all the flows to ensure that function pointer exists prior
to accessing it.

This is much safer than checking the uverbs_ex_mask variable, especially
since we know that test isn't working properly and will be removed
in -next.

This prevents a user triggereable oops.

Signed-off-by: Leon Romanovsky 
Signed-off-by: Jason Gunthorpe

RDMA/uverbs: Sanitize user entered port numbers prior to access it

2018-02-15T22:31:27+00:00

==================================================================
BUG: KASAN: use-after-free in copy_ah_attr_from_uverbs+0x6f2/0x8c0
Read of size 4 at addr ffff88006476a198 by task syzkaller697701/265

CPU: 0 PID: 265 Comm: syzkaller697701 Not tainted 4.15.0+ #90
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.7.5-0-ge51488c-20140602_164612-nilsson.home.kraxel.org 04/01/2014
Call Trace:
 dump_stack+0xde/0x164
 ? dma_virt_map_sg+0x22c/0x22c
 ? show_regs_print_info+0x17/0x17
 ? lock_contended+0x11a0/0x11a0
 print_address_description+0x83/0x3e0
 kasan_report+0x18c/0x4b0
 ? copy_ah_attr_from_uverbs+0x6f2/0x8c0
 ? copy_ah_attr_from_uverbs+0x6f2/0x8c0
 ? lookup_get_idr_uobject+0x120/0x200
 ? copy_ah_attr_from_uverbs+0x6f2/0x8c0
 copy_ah_attr_from_uverbs+0x6f2/0x8c0
 ? modify_qp+0xd0e/0x1350
 modify_qp+0xd0e/0x1350
 ib_uverbs_modify_qp+0xf9/0x170
 ? ib_uverbs_query_qp+0xa70/0xa70
 ib_uverbs_write+0x7f9/0xef0
 ? attach_entity_load_avg+0x8b0/0x8b0
 ? ib_uverbs_query_qp+0xa70/0xa70
 ? uverbs_devnode+0x110/0x110
 ? cyc2ns_read_end+0x10/0x10
 ? print_irqtrace_events+0x280/0x280
 ? sched_clock_cpu+0x18/0x200
 ? _raw_spin_unlock_irq+0x29/0x40
 ? _raw_spin_unlock_irq+0x29/0x40
 ? _raw_spin_unlock_irq+0x29/0x40
 ? time_hardirqs_on+0x27/0x670
 __vfs_write+0x10d/0x700
 ? uverbs_devnode+0x110/0x110
 ? kernel_read+0x170/0x170
 ? _raw_spin_unlock_irq+0x29/0x40
 ? finish_task_switch+0x1bd/0x7a0
 ? finish_task_switch+0x194/0x7a0
 ? prandom_u32_state+0xe/0x180
 ? rcu_read_unlock+0x80/0x80
 ? security_file_permission+0x93/0x260
 vfs_write+0x1b0/0x550
 SyS_write+0xc7/0x1a0
 ? SyS_read+0x1a0/0x1a0
 ? trace_hardirqs_on_thunk+0x1a/0x1c
 entry_SYSCALL_64_fastpath+0x1e/0x8b
RIP: 0033:0x433c29
RSP: 002b:00007ffcf2be82a8 EFLAGS: 00000217

Allocated by task 62:
 kasan_kmalloc+0xa0/0xd0
 kmem_cache_alloc+0x141/0x480
 dup_fd+0x101/0xcc0
 copy_process.part.62+0x166f/0x4390
 _do_fork+0x1cb/0xe90
 kernel_thread+0x34/0x40
 call_usermodehelper_exec_work+0x112/0x260
 process_one_work+0x929/0x1aa0
 worker_thread+0x5c6/0x12a0
 kthread+0x346/0x510
 ret_from_fork+0x3a/0x50

Freed by task 259:
 kasan_slab_free+0x71/0xc0
 kmem_cache_free+0xf3/0x4c0
 put_files_struct+0x225/0x2c0
 exit_files+0x88/0xc0
 do_exit+0x67c/0x1520
 do_group_exit+0xe8/0x380
 SyS_exit_group+0x1e/0x20
 entry_SYSCALL_64_fastpath+0x1e/0x8b

The buggy address belongs to the object at ffff88006476a000
 which belongs to the cache files_cache of size 832
The buggy address is located 408 bytes inside of
 832-byte region [ffff88006476a000, ffff88006476a340)
The buggy address belongs to the page:
page:ffffea000191da80 count:1 mapcount:0 mapping:          (null) index:0x0 compound_mapcount: 0
flags: 0x4000000000008100(slab|head)
raw: 4000000000008100 0000000000000000 0000000000000000 0000000100080008
raw: 0000000000000000 0000000100000001 ffff88006bcf7a80 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88006476a080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88006476a100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88006476a180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                            ^
 ffff88006476a200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88006476a280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

Cc: syzkaller 
Cc:  # 4.11
Fixes: 44c58487d51a ("IB/core: Define 'ib' and 'roce' rdma_ah_attr types")
Reported-by: Noa Osherovich 
Signed-off-by: Leon Romanovsky 
Signed-off-by: Jason Gunthorpe

RDMA/uverbs: Fix circular locking dependency

2018-02-15T22:31:27+00:00

Avoid circular locking dependency by calling
to uobj_alloc_commit() outside of xrcd_tree_mutex lock.

======================================================
WARNING: possible circular locking dependency detected
4.15.0+ #87 Not tainted
------------------------------------------------------
syzkaller401056/269 is trying to acquire lock:
 (&uverbs_dev->xrcd_tree_mutex){+.+.}, at: [<000000006c12d2cd>] uverbs_free_xrcd+0xd2/0x360

but task is already holding lock:
 (&ucontext->uobjects_lock){+.+.}, at: [<00000000da010f09>] uverbs_cleanup_ucontext+0x168/0x730

which lock already depends on the new lock.

the existing dependency chain (in reverse order) is:

-> #1 (&ucontext->uobjects_lock){+.+.}:
       __mutex_lock+0x111/0x1720
       rdma_alloc_commit_uobject+0x22c/0x600
       ib_uverbs_open_xrcd+0x61a/0xdd0
       ib_uverbs_write+0x7f9/0xef0
       __vfs_write+0x10d/0x700
       vfs_write+0x1b0/0x550
       SyS_write+0xc7/0x1a0
       entry_SYSCALL_64_fastpath+0x1e/0x8b

-> #0 (&uverbs_dev->xrcd_tree_mutex){+.+.}:
       lock_acquire+0x19d/0x440
       __mutex_lock+0x111/0x1720
       uverbs_free_xrcd+0xd2/0x360
       remove_commit_idr_uobject+0x6d/0x110
       uverbs_cleanup_ucontext+0x2f0/0x730
       ib_uverbs_cleanup_ucontext.constprop.3+0x52/0x120
       ib_uverbs_close+0xf2/0x570
       __fput+0x2cd/0x8d0
       task_work_run+0xec/0x1d0
       do_exit+0x6a1/0x1520
       do_group_exit+0xe8/0x380
       SyS_exit_group+0x1e/0x20
       entry_SYSCALL_64_fastpath+0x1e/0x8b

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&ucontext->uobjects_lock);
                               lock(&uverbs_dev->xrcd_tree_mutex);
                               lock(&ucontext->uobjects_lock);
  lock(&uverbs_dev->xrcd_tree_mutex);

 *** DEADLOCK ***

3 locks held by syzkaller401056/269:
 #0:  (&file->cleanup_mutex){+.+.}, at: [<00000000c9f0c252>] ib_uverbs_close+0xac/0x570
 #1:  (&ucontext->cleanup_rwsem){++++}, at: [<00000000b6994d49>] uverbs_cleanup_ucontext+0xf6/0x730
 #2:  (&ucontext->uobjects_lock){+.+.}, at: [<00000000da010f09>] uverbs_cleanup_ucontext+0x168/0x730

stack backtrace:
CPU: 0 PID: 269 Comm: syzkaller401056 Not tainted 4.15.0+ #87
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.7.5-0-ge51488c-20140602_164612-nilsson.home.kraxel.org 04/01/2014
Call Trace:
 dump_stack+0xde/0x164
 ? dma_virt_map_sg+0x22c/0x22c
 ? uverbs_cleanup_ucontext+0x168/0x730
 ? console_unlock+0x502/0xbd0
 print_circular_bug.isra.24+0x35e/0x396
 ? print_circular_bug_header+0x12e/0x12e
 ? find_usage_backwards+0x30/0x30
 ? entry_SYSCALL_64_fastpath+0x1e/0x8b
 validate_chain.isra.28+0x25d1/0x40c0
 ? check_usage+0xb70/0xb70
 ? graph_lock+0x160/0x160
 ? find_usage_backwards+0x30/0x30
 ? cyc2ns_read_end+0x10/0x10
 ? print_irqtrace_events+0x280/0x280
 ? __lock_acquire+0x93d/0x1630
 __lock_acquire+0x93d/0x1630
 lock_acquire+0x19d/0x440
 ? uverbs_free_xrcd+0xd2/0x360
 __mutex_lock+0x111/0x1720
 ? uverbs_free_xrcd+0xd2/0x360
 ? uverbs_free_xrcd+0xd2/0x360
 ? __mutex_lock+0x828/0x1720
 ? mutex_lock_io_nested+0x1550/0x1550
 ? uverbs_cleanup_ucontext+0x168/0x730
 ? __lock_acquire+0x9a9/0x1630
 ? mutex_lock_io_nested+0x1550/0x1550
 ? uverbs_cleanup_ucontext+0xf6/0x730
 ? lock_contended+0x11a0/0x11a0
 ? uverbs_free_xrcd+0xd2/0x360
 uverbs_free_xrcd+0xd2/0x360
 remove_commit_idr_uobject+0x6d/0x110
 uverbs_cleanup_ucontext+0x2f0/0x730
 ? sched_clock_cpu+0x18/0x200
 ? uverbs_close_fd+0x1c0/0x1c0
 ib_uverbs_cleanup_ucontext.constprop.3+0x52/0x120
 ib_uverbs_close+0xf2/0x570
 ? ib_uverbs_remove_one+0xb50/0xb50
 ? ib_uverbs_remove_one+0xb50/0xb50
 __fput+0x2cd/0x8d0
 task_work_run+0xec/0x1d0
 do_exit+0x6a1/0x1520
 ? fsnotify_first_mark+0x220/0x220
 ? exit_notify+0x9f0/0x9f0
 ? entry_SYSCALL_64_fastpath+0x5/0x8b
 ? entry_SYSCALL_64_fastpath+0x5/0x8b
 ? trace_hardirqs_on_thunk+0x1a/0x1c
 ? time_hardirqs_on+0x27/0x670
 ? time_hardirqs_off+0x27/0x490
 ? syscall_return_slowpath+0x6c/0x460
 ? entry_SYSCALL_64_fastpath+0x5/0x8b
 do_group_exit+0xe8/0x380
 SyS_exit_group+0x1e/0x20
 entry_SYSCALL_64_fastpath+0x1e/0x8b
RIP: 0033:0x431ce9

Cc: syzkaller 
Cc:  # 4.11
Fixes: fd3c7904db6e ("IB/core: Change idr objects to use the new schema")
Reported-by: Noa Osherovich 
Signed-off-by: Leon Romanovsky 
Signed-off-by: Jason Gunthorpe

RDMA/uverbs: Fix bad unlock balance in ib_uverbs_close_xrcd

2018-02-15T22:31:27+00:00

There is no matching lock for this mutex. Git history suggests this is
just a missed remnant from an earlier version of the function before
this locking was moved into uverbs_free_xrcd.

Originally this lock was protecting the xrcd_table_delete()

=====================================
WARNING: bad unlock balance detected!
4.15.0+ #87 Not tainted
-------------------------------------
syzkaller223405/269 is trying to release lock (&uverbs_dev->xrcd_tree_mutex) at:
[<00000000b8703372>] ib_uverbs_close_xrcd+0x195/0x1f0
but there are no more locks to release!

other info that might help us debug this:
1 lock held by syzkaller223405/269:
 #0:  (&uverbs_dev->disassociate_srcu){....}, at: [<000000005af3b960>] ib_uverbs_write+0x265/0xef0

stack backtrace:
CPU: 0 PID: 269 Comm: syzkaller223405 Not tainted 4.15.0+ #87
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.7.5-0-ge51488c-20140602_164612-nilsson.home.kraxel.org 04/01/2014
Call Trace:
 dump_stack+0xde/0x164
 ? dma_virt_map_sg+0x22c/0x22c
 ? ib_uverbs_write+0x265/0xef0
 ? console_unlock+0x502/0xbd0
 ? ib_uverbs_close_xrcd+0x195/0x1f0
 print_unlock_imbalance_bug+0x131/0x160
 lock_release+0x59d/0x1100
 ? ib_uverbs_close_xrcd+0x195/0x1f0
 ? lock_acquire+0x440/0x440
 ? lock_acquire+0x440/0x440
 __mutex_unlock_slowpath+0x88/0x670
 ? wait_for_completion+0x4c0/0x4c0
 ? rdma_lookup_get_uobject+0x145/0x2f0
 ib_uverbs_close_xrcd+0x195/0x1f0
 ? ib_uverbs_open_xrcd+0xdd0/0xdd0
 ib_uverbs_write+0x7f9/0xef0
 ? cyc2ns_read_end+0x10/0x10
 ? ib_uverbs_open_xrcd+0xdd0/0xdd0
 ? uverbs_devnode+0x110/0x110
 ? cyc2ns_read_end+0x10/0x10
 ? cyc2ns_read_end+0x10/0x10
 ? sched_clock_cpu+0x18/0x200
 __vfs_write+0x10d/0x700
 ? uverbs_devnode+0x110/0x110
 ? kernel_read+0x170/0x170
 ? __fget+0x358/0x5d0
 ? security_file_permission+0x93/0x260
 vfs_write+0x1b0/0x550
 SyS_write+0xc7/0x1a0
 ? SyS_read+0x1a0/0x1a0
 ? trace_hardirqs_on_thunk+0x1a/0x1c
 entry_SYSCALL_64_fastpath+0x1e/0x8b
RIP: 0033:0x4335c9

Cc: syzkaller 
Cc:  # 4.11
Fixes: fd3c7904db6e ("IB/core: Change idr objects to use the new schema")
Reported-by: Noa Osherovich 
Signed-off-by: Leon Romanovsky 
Signed-off-by: Jason Gunthorpe

RDMA/restrack: Increment CQ restrack object before committing

2018-02-15T22:31:26+00:00

Once the uobj is committed it is immediately possible another thread
could destroy it, which worst case, can result in a use-after-free
of the restrack objects.

Cc: syzkaller 
Fixes: 08f294a1524b ("RDMA/core: Add resource tracking for create and destroy CQs")
Reported-by: Noa Osherovich 
Signed-off-by: Leon Romanovsky 
Signed-off-by: Jason Gunthorpe

RDMA/uverbs: Protect from command mask overflow

2018-02-15T22:31:26+00:00

The command number is not bounds checked against the command mask before it
is shifted, resulting in an ubsan hit. This does not cause malfunction since
the command number is eventually bounds checked, but we can make this ubsan
clean by moving the bounds check to before the mask check.

================================================================================
UBSAN: Undefined behaviour in
drivers/infiniband/core/uverbs_main.c:647:21
shift exponent 207 is too large for 64-bit type 'long long unsigned int'
CPU: 0 PID: 446 Comm: syz-executor3 Not tainted 4.15.0-rc2+ #61
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
rel-1.7.5-0-ge51488c-20140602_164612-nilsson.home.kraxel.org 04/01/2014
Call Trace:
dump_stack+0xde/0x164
? dma_virt_map_sg+0x22c/0x22c
ubsan_epilogue+0xe/0x81
__ubsan_handle_shift_out_of_bounds+0x293/0x2f7
? debug_check_no_locks_freed+0x340/0x340
? __ubsan_handle_load_invalid_value+0x19b/0x19b
? lock_acquire+0x440/0x440
? lock_acquire+0x19d/0x440
? __might_fault+0xf4/0x240
? ib_uverbs_write+0x68d/0xe20
ib_uverbs_write+0x68d/0xe20
? __lock_acquire+0xcf7/0x3940
? uverbs_devnode+0x110/0x110
? cyc2ns_read_end+0x10/0x10
? sched_clock_cpu+0x18/0x200
? sched_clock_cpu+0x18/0x200
__vfs_write+0x10d/0x700
? uverbs_devnode+0x110/0x110
? kernel_read+0x170/0x170
? __fget+0x35b/0x5d0
? security_file_permission+0x93/0x260
vfs_write+0x1b0/0x550
SyS_write+0xc7/0x1a0
? SyS_read+0x1a0/0x1a0
? trace_hardirqs_on_thunk+0x1a/0x1c
entry_SYSCALL_64_fastpath+0x18/0x85
RIP: 0033:0x448e29
RSP: 002b:00007f033f567c58 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f033f5686bc RCX: 0000000000448e29
RDX: 0000000000000060 RSI: 0000000020001000 RDI: 0000000000000012
RBP: 000000000070bea0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000000056a0 R14: 00000000006e8740 R15: 0000000000000000
================================================================================

Cc: syzkaller 
Cc:  # 4.5
Fixes: 2dbd5186a39c ("IB/core: IB/core: Allow legacy verbs through extended interfaces")
Reported-by: Noa Osherovich 
Reviewed-by: Matan Barak 
Signed-off-by: Leon Romanovsky 
Signed-off-by: Jason Gunthorpe

IB/uverbs: Fix unbalanced unlock on error path for rdma_explicit_destroy

2018-02-15T22:31:26+00:00

If remove_commit fails then the lock is left locked while the uobj still
exists. Eventually the kernel will deadlock.

lockdep detects this and says:

 test/4221 is leaving the kernel with locks still held!
 1 lock held by test/4221:
  #0:  (&ucontext->cleanup_rwsem){.+.+}, at: [<000000001e5c7523>] rdma_explicit_destroy+0x37/0x120 [ib_uverbs]

Fixes: 4da70da23e9b ("IB/core: Explicitly destroy an object while keeping uobject")
Signed-off-by: Leon Romanovsky 
Reviewed-by: Dennis Dalessandro 
Signed-off-by: Jason Gunthorpe

IB/uverbs: Improve lockdep_check

2018-02-15T21:59:47+00:00

This is really being used as an assert that the expected usecnt
is being held and implicitly that the usecnt is valid. Rename it to
assert_uverbs_usecnt and tighten the checks to only accept valid
values of usecnt (eg 0 and < -1 are invalid).

The tigher checkes make the assertion cover more cases and is more
likely to find bugs via syzkaller/etc.

Fixes: 3832125624b7 ("IB/core: Add support for idr types")
Signed-off-by: Leon Romanovsky 
Signed-off-by: Jason Gunthorpe