IB/iser: reject a remote invalidation of an unregistered direction

In the Linux kernel, the following vulnerability has been resolved:

IB/iser: reject a remote invalidation of an unregistered direction

A write command whose data is sent entirely as immediate data is not
registered. iser_reg_mem_fastreg() takes the DMA key path and leaves
rdma_reg[ISER_DIR_OUT].desc at NULL, while iser_dma_map_task_data() has
already set dir[ISER_DIR_OUT].

iser_check_remote_inv() looks at dir[] alone and hands the descriptor to
iser_inv_desc(), which reads desc->sig_protected. A target that answers
such a command with IB_WR_SEND_WITH_INV faults the initiator.
Leaving those commands unregistered is deliberate.

The same function already terminates the connection when a target sends
a remote invalidation the initiator did not ask for. A target that
invalidates a direction that was never registered is in the same class,
so give it the same answer.

Oops: general protection fault, probably for non-canonical address 0xdffffc0000000004: 0000 [#1] SMP KASAN NOPTI
KASAN: null-ptr-deref in range [0x0000000000000020-0x0000000000000027]
CPU: 0 UID: 0 PID: 40 Comm: kworker/u8:2 Not tainted 7.2.0-rc5-ISERHOST-gf5098b6bae76-dirty #3 PREEMPT(lazy)
Hardware name: QEMU Ubuntu 24.04 PC v2 (i440FX + PIIX, arch_caps fix, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
Workqueue: rxe_wq do_work
RIP: 0010:iser_task_rsp+0x6d6/0xec0
Code: 48 c1 ea 03 80 3c 02 00 0f 85 ba 06 00 00 48 8b 9b 78 01 00 00 48 b8 00 00 00 00 00 fc ff df 48 8d 7b 20 48 89 fa 48 c1 ea 03 <0f> b6 04 02 84 c0 74 06 0f 8e 76 06 00 00 80 7b 20 00 0f 84 3d 04
RSP: 0018:ffff88811b008db8 EFLAGS: 00010202
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000001848
RDX: 0000000000000004 RSI: 1ffff11021587b12 RDI: 0000000000000020
RBP: ffff88810adc1ae4 R08: ffff888109b7f860 R09: ffffffff90a922c0
R10: ffff88810adc1a1c R11: 000000000000003c R12: ffff888109b7f800
R13: ffff88810adc1acc R14: ffff888109b7f820 R15: 0000000000000000
FS: 0000000000000000(0000) GS:ffff88818a676000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000005afe2b CR3: 000000010af23005 CR4: 0000000000770ef0
PKRU: 55555554
Call Trace:
<IRQ>
__ib_process_cq+0xe1/0x390
ib_poll_handler+0x6e/0x200
irq_poll_softirq+0x1df/0x480
? clockevents_program_event+0x2ba/0x860
? __pfx_irq_poll_softirq+0x10/0x10
handle_softirqs+0x18e/0x590
? __pfx_handle_softirqs+0x10/0x10
? __hrtimer_rearm_deferred+0x156/0x450
do_softirq+0x3b/0x60
</IRQ>
<TASK>
__local_bh_enable_ip+0x61/0x70
__alloc_skb+0x732/0x890
? _raw_spin_lock_irqsave+0x85/0xe0
? __pfx___alloc_skb+0x10/0x10
? _raw_read_unlock_irqrestore+0x16/0x50
rxe_init_packet+0x16b/0x4f0
prepare_ack_packet+0xb8/0x830
rxe_receiver+0x499/0x9980
? __pfx_rxe_receiver+0x10/0x10
? rxe_completer+0x29e5/0x38c0
? hrtimer_start_range_ns_common+0x75f/0x1730
? hrtimer_start_range_ns+0xa6/0x2c0
? __pfx__raw_spin_lock_irqsave+0x10/0x10
? __pfx_rxe_receiver+0x10/0x10
do_work+0x144/0x470
process_one_work+0x633/0x1030
? assign_work+0x11d/0x370
worker_thread+0x45b/0xd10
? __pfx_worker_thread+0x10/0x10
kthread+0x2c6/0x3b0
? recalc_sigpending+0x15c/0x1e0
? __pfx_kthread+0x10/0x10
ret_from_fork+0x36e/0x5a0
? __pfx_ret_from_fork+0x10/0x10
? __switch_to+0x572/0xdd0
? __pfx_kthread+0x10/0x10
ret_from_fork_asm+0x1a/0x30
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---