[PATCH nvme] nvmet-rdma: reject short connection requests

[bestswngs@gmail.com]

From: Weiming Shi <bestswngs@gmail.com>

nvmet_rdma_parse_cm_connect_req() treats RDMA-CM private data as a
struct nvme_rdma_cm_req but accepts any nonzero private_data_len.  The
iWARP path allocates exactly the peer-provided length, so a six-byte MPA
request reaches the parser and the hsqsize load reads two bytes past the
allocation.

Require the complete request structure before reading any of its fields.
The decoded KASAN report is:

  BUG: KASAN: slab-out-of-bounds in nvmet_rdma_cm_handler
    (drivers/nvme/target/rdma.c:1427 drivers/nvme/target/rdma.c:1475
     drivers/nvme/target/rdma.c:1614 drivers/nvme/target/rdma.c:1814)
  Read of size 2 at addr ff1100010459d366 by task kworker/u16:1/41
  Workqueue: iw_cm_wq cm_work_handler
  Call Trace:
   <TASK>
   dump_stack_lvl (lib/dump_stack.c:94 lib/dump_stack.c:120)
   print_report (mm/kasan/report.c:378 mm/kasan/report.c:482)
   kasan_report (mm/kasan/report.c:595)
   nvmet_rdma_cm_handler
    (drivers/nvme/target/rdma.c:1427 drivers/nvme/target/rdma.c:1475
     drivers/nvme/target/rdma.c:1614 drivers/nvme/target/rdma.c:1814)
   cma_cm_event_handler (drivers/infiniband/core/cma.c:2181)
   iw_conn_req_handler (drivers/infiniband/core/cma.c:2640)
   cm_work_handler
    (drivers/infiniband/core/cm.c:2502
     drivers/infiniband/core/cm.c:3858)
   process_one_work (kernel/workqueue.c:3396)
   worker_thread (kernel/workqueue.c:3479 kernel/workqueue.c:3560)
   kthread (kernel/kthread.c:436)
   ret_from_fork (arch/x86/kernel/process.c:158)
   ret_from_fork_asm (arch/x86/entry/entry_64.S:245)
   </TASK>

  Allocated by task 12:
   __kasan_kmalloc (mm/kasan/common.c:398 mm/kasan/common.c:415)
   __kmalloc_node_track_caller_noprof
    (mm/slub.c:5414 mm/slub.c:5545)
   kmemdup_noprof (mm/util.c:138)
   cm_event_handler
    (drivers/infiniband/core/iwcm.c:194
     drivers/infiniband/core/iwcm.c:1076)
   siw_cm_upcall (drivers/infiniband/sw/siw/siw_cm.c:408)
   siw_proc_mpareq (drivers/infiniband/sw/siw/siw_cm.c:750)
   siw_cm_work_handler (drivers/infiniband/sw/siw/siw_cm.c:1086)

  The buggy address is located 0 bytes to the right of
  allocated 6-byte region [ff1100010459d360, ff1100010459d366)

Cc: stable@vger.kernel.org
Fixes: 8f000cac6e7a ("nvmet-rdma: add a NVMe over Fabrics RDMA target driver")
Reported-by: <co+e015e82956da641b@bugs.sh>
Assisted-by: LLM
Signed-off-by: Weiming Shi <bestswngs@gmail.com>
---
 drivers/nvme/target/rdma.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/nvme/target/rdma.c b/drivers/nvme/target/rdma.c
index ffa1e172c..075ab58d8 100644
--- a/drivers/nvme/target/rdma.c
+++ b/drivers/nvme/target/rdma.c
@@ -1412,7 +1412,7 @@ nvmet_rdma_parse_cm_connect_req(struct rdma_conn_param *conn,
 	struct nvme_rdma_cm_req *req;
 
 	req = (struct nvme_rdma_cm_req *)conn->private_data;
-	if (!req || conn->private_data_len == 0)
+	if (!req || conn->private_data_len < sizeof(*req))
 		return NVME_RDMA_CM_INVALID_LEN;
 
 	if (le16_to_cpu(req->recfmt) != NVME_RDMA_CM_FMT_1_0)
-- 
2.55.0