[PATCH v2] 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 ]---

Fixes: 59caaed7a72a ("IB/iser: Support the remote invalidation exception")
Cc: [email protected]
Suggested-by: Max Gurtovoy <[email protected]>
Signed-off-by: Yehyeong Lee <[email protected]>
---
Changes since v1:
 - reject instead of skipping (Max Gurtovoy; the AI review of v1 asked
   the same thing).  v1 let a bogus remote invalidation through
   silently; this reuses the -EPROTO path the function already has for
   an unexpected invalidation.
 - drop the claim about bidirectional commands, which was wrong:
   ISCSI_FLAG_CMD_READ and ISCSI_FLAG_CMD_WRITE are set in one if/else
   in libiscsi.c, so they cannot both be set.

v1: https://lore.kernel.org/linux-rdma/[email protected]/

Measured over rxe with KASAN against an isert target that sends
SEND_WITH_INV for a command it never registered, armed only after the
disk is up so the window is open when it arrives: the fault appeared in
5 of 5 runs unpatched and in none of 5 with this patch.  A conforming
target is unaffected over 5 runs each way; the new path is not reached
at all there.

Against the hostile target the two forms differ in one measured way: v1
completed 6 to 21 small writes before the session collapsed, this one
completes none.  Neither approaches the 20000 the workload asks for.  No
reconnect loop was observed with either form - the session came back up
zero times in ten runs.

 drivers/infiniband/ulp/iser/iser_initiator.c | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/drivers/infiniband/ulp/iser/iser_initiator.c b/drivers/infiniband/ulp/iser/iser_initiator.c
index 12a2d12fef070..7ea6888b479cf 100644
--- a/drivers/infiniband/ulp/iser/iser_initiator.c
+++ b/drivers/infiniband/ulp/iser/iser_initiator.c
@@ -598,11 +598,8 @@ static int iser_check_remote_inv(struct iser_conn *iser_conn, struct ib_wc *wc,
 		iser_dbg("conn %p: remote invalidation for rkey %#x\n",
 			 iser_conn, rkey);
 
-		if (unlikely(!iser_conn->snd_w_inv)) {
-			iser_err("conn %p: unexpected remote invalidation, terminating connection\n",
-				 iser_conn);
-			return -EPROTO;
-		}
+		if (unlikely(!iser_conn->snd_w_inv))
+			goto bad_inv;
 
 		task = iscsi_itt_to_ctask(iser_conn->iscsi_conn, hdr->itt);
 		if (likely(task)) {
@@ -611,12 +608,16 @@ static int iser_check_remote_inv(struct iser_conn *iser_conn, struct ib_wc *wc,
 
 			if (iser_task->dir[ISER_DIR_IN]) {
 				desc = iser_task->rdma_reg[ISER_DIR_IN].desc;
+				if (unlikely(!desc))
+					goto bad_inv;
 				if (unlikely(iser_inv_desc(desc, rkey)))
 					return -EINVAL;
 			}
 
 			if (iser_task->dir[ISER_DIR_OUT]) {
 				desc = iser_task->rdma_reg[ISER_DIR_OUT].desc;
+				if (unlikely(!desc))
+					goto bad_inv;
 				if (unlikely(iser_inv_desc(desc, rkey)))
 					return -EINVAL;
 			}
@@ -627,6 +628,11 @@ static int iser_check_remote_inv(struct iser_conn *iser_conn, struct ib_wc *wc,
 	}
 
 	return 0;
+
+bad_inv:
+	iser_err("conn %p: unexpected remote invalidation, terminating connection\n",
+		 iser_conn);
+	return -EPROTO;
 }
 
 
-- 
2.43.0