Add a check for the length of the qpin structure to prevent out-of-bounds reads

BUG: KASAN: slab-out-of-bounds in create_raw_packet_qp+0x114c/0x15e2
Read of size 8192 at addr ffff880066b99290 by task syz-executor3/549

CPU: 3 PID: 549 Comm: syz-executor3 Not tainted 4.15.0-rc2+ #27 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+0x8d/0xd4
 print_address_description+0x73/0x290
 kasan_report+0x25c/0x370
 ? create_raw_packet_qp+0x114c/0x15e2
 memcpy+0x1f/0x50
 create_raw_packet_qp+0x114c/0x15e2
 ? create_raw_packet_qp_tis.isra.28+0x13d/0x13d
 ? lock_acquire+0x370/0x370
 create_qp_common+0x2245/0x3b50
 ? destroy_qp_user.isra.47+0x100/0x100
 ? kasan_kmalloc+0x13d/0x170
 ? sched_clock_cpu+0x18/0x180
 ? fs_reclaim_acquire.part.15+0x5/0x30
 ? __lock_acquire+0xa11/0x1da0
 ? sched_clock_cpu+0x18/0x180
 ? kmem_cache_alloc_trace+0x17e/0x310
 ? mlx5_ib_create_qp+0x30e/0x17b0
 mlx5_ib_create_qp+0x33d/0x17b0
 ? sched_clock_cpu+0x18/0x180
 ? create_qp_common+0x3b50/0x3b50
 ? lock_acquire+0x370/0x370
 ? __radix_tree_lookup+0x180/0x220
 ? uverbs_try_lock_object+0x68/0xc0
 ? rdma_lookup_get_uobject+0x114/0x240
 create_qp.isra.5+0xce4/0x1e20
 ? ib_uverbs_ex_create_cq_cb+0xa0/0xa0
 ? copy_ah_attr_from_uverbs.isra.2+0xa00/0xa00
 ? ib_uverbs_cq_event_handler+0x160/0x160
 ? __might_fault+0x17c/0x1c0
 ib_uverbs_create_qp+0x21b/0x2a0
 ? ib_uverbs_destroy_cq+0x2e0/0x2e0
 ib_uverbs_write+0x55a/0xad0
 ? ib_uverbs_destroy_cq+0x2e0/0x2e0
 ? ib_uverbs_destroy_cq+0x2e0/0x2e0
 ? ib_uverbs_open+0x760/0x760
 ? futex_wake+0x147/0x410
 ? check_prev_add+0x1680/0x1680
 ? do_futex+0x3d3/0xa60
 ? sched_clock_cpu+0x18/0x180
 __vfs_write+0xf7/0x5c0
 ? ib_uverbs_open+0x760/0x760
 ? kernel_read+0x110/0x110
 ? lock_acquire+0x370/0x370
 ? __fget+0x264/0x3b0
 vfs_write+0x18a/0x460
 SyS_write+0xc7/0x1a0
 ? SyS_read+0x1a0/0x1a0
 ? trace_hardirqs_on_thunk+0x1a/0x1c
 entry_SYSCALL_64_fastpath+0x18/0x85
RIP: 0033:0x4477b9
RSP: 002b:00007f1822cadc18 EFLAGS: 00000292 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 00000000004477b9
RDX: 0000000000000070 RSI: 000000002000a000 RDI: 0000000000000005
RBP: 0000000000708000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000292 R12: 00000000ffffffff
R13: 0000000000005d70 R14: 00000000006e6e30 R15: 0000000020010ff0

Allocated by task 549:
 __kmalloc+0x15e/0x340
 kvmalloc_node+0xa1/0xd0
 create_user_qp.isra.46+0xd42/0x1610
 create_qp_common+0x2e63/0x3b50
 mlx5_ib_create_qp+0x33d/0x17b0
 create_qp.isra.5+0xce4/0x1e20
 ib_uverbs_create_qp+0x21b/0x2a0
 ib_uverbs_write+0x55a/0xad0
 __vfs_write+0xf7/0x5c0
 vfs_write+0x18a/0x460
 SyS_write+0xc7/0x1a0
 entry_SYSCALL_64_fastpath+0x18/0x85

Freed by task 368:
 kfree+0xeb/0x2f0
 kernfs_fop_release+0x140/0x180
 __fput+0x266/0x700
 task_work_run+0x104/0x180
 exit_to_usermode_loop+0xf7/0x110
 syscall_return_slowpath+0x298/0x370
 entry_SYSCALL_64_fastpath+0x83/0x85

The buggy address belongs to the object at ffff880066b99180  which
belongs to the cache kmalloc-512 of size 512 The buggy address is
located 272 bytes inside of  512-byte region [ffff880066b99180,
ffff880066b99380) The buggy address belongs to the page:
page:000000006040eedd count:1 mapcount:0 mapping:          (null)
index:0x0 compound_mapcount: 0
flags: 0x4000000000008100(slab|head)
raw: 4000000000008100 0000000000000000 0000000000000000 0000000180190019
raw: ffffea00019a7500 0000000b0000000b ffff88006c403080 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff880066b99180: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff880066b99200: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff880066b99280: 00 00 fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                         ^
 ffff880066b99300: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff880066b99380: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc

Cc: syzkaller <syzkaller@googlegroups.com>
Fixes: 0fb2ed66 ("IB/mlx5: Add create and destroy functionality for Raw Packet QP")
Signed-off-by: Boris Pismenny <borisp@mellanox.com>
Signed-off-by: Leon Romanovsky <leon@kernel.org>
Signed-off-by: Doug Ledford <dledford@redhat.com>