[PATCH] RDMA/siw: Fix immediate work request flush to completion queue.

[Bernard Metzler]

Correctly set send queue element opcode during immediate work request
flushing in post sendqueue operation, if the QP is in ERROR state.
An undefined ocode value results in out-of-bounds access to an array
for mapping the opcode between siw internal and RDMA core representation
in work completion generation. It resulted in a KASAN BUG report
of type 'global-out-of-bounds' during NFSoRDMA testing.
This patch further fixes a potential case of a malicious user which may
write undefined values for completion queue elements status or opcode,
if the CQ is memory mapped to user land. It avoids the same out-of-bounds
access to arrays for status and opcode mapping as described above.

Fixes: 303ae1cdfdf7 ("rdma/siw: application interface")
Fixes: b0fff7317bb4 ("rdma/siw: completion queue methods")

Reported-by: Olga Kornievskaia <kolga@xxxxxxxxxx>
Signed-off-by: Bernard Metzler <bmt@xxxxxxxxxxxxxx>
---
 drivers/infiniband/sw/siw/siw_cq.c    | 24 ++++++++++++++--
 drivers/infiniband/sw/siw/siw_verbs.c | 40 ++++++++++++++++++++++++---
 2 files changed, 58 insertions(+), 6 deletions(-)

diff --git a/drivers/infiniband/sw/siw/siw_cq.c b/drivers/infiniband/sw/siw/siw_cq.c
index d68e37859e73..acc7bcd538b5 100644
--- a/drivers/infiniband/sw/siw/siw_cq.c
+++ b/drivers/infiniband/sw/siw/siw_cq.c
@@ -56,8 +56,6 @@ int siw_reap_cqe(struct siw_cq *cq, struct ib_wc *wc)
 	if (READ_ONCE(cqe->flags) & SIW_WQE_VALID) {
 		memset(wc, 0, sizeof(*wc));
 		wc->wr_id = cqe->id;
-		wc->status = map_cqe_status[cqe->status].ib;
-		wc->opcode = map_wc_opcode[cqe->opcode];
 		wc->byte_len = cqe->bytes;
 
 		/*
@@ -71,10 +69,32 @@ int siw_reap_cqe(struct siw_cq *cq, struct ib_wc *wc)
 				wc->wc_flags = IB_WC_WITH_INVALIDATE;
 			}
 			wc->qp = cqe->base_qp;
+			wc->opcode = map_wc_opcode[cqe->opcode];
+			wc->status = map_cqe_status[cqe->status].ib;
 			siw_dbg_cq(cq,
 				   "idx %u, type %d, flags %2x, id 0x%pK\n",
 				   cq->cq_get % cq->num_cqe, cqe->opcode,
 				   cqe->flags, (void *)(uintptr_t)cqe->id);
+		} else {
+			/*
+			 * A malicious user may set invalid opcode or
+			 * status in the user mmapped CQE array.
+			 * Sanity check and correct values in that case
+			 * to avoid out-of-bounds access to global arrays
+			 * for opcode and status mapping.
+			 */
+			u8 opcode = cqe->opcode;
+			u16 status = cqe->status;
+
+			if (opcode >= SIW_NUM_OPCODES) {
+				opcode = 0;
+				status = IB_WC_GENERAL_ERR;
+			} else if (status >= SIW_NUM_WC_STATUS) {
+				status = IB_WC_GENERAL_ERR;
+			}
+			wc->opcode = map_wc_opcode[opcode];
+			wc->status = map_cqe_status[status].ib;
+
 		}
 		WRITE_ONCE(cqe->flags, 0);
 		cq->cq_get++;
diff --git a/drivers/infiniband/sw/siw/siw_verbs.c b/drivers/infiniband/sw/siw/siw_verbs.c
index 3e814cfb298c..8021fbd004b0 100644
--- a/drivers/infiniband/sw/siw/siw_verbs.c
+++ b/drivers/infiniband/sw/siw/siw_verbs.c
@@ -676,13 +676,45 @@ static int siw_copy_inline_sgl(const struct ib_send_wr *core_wr,
 static int siw_sq_flush_wr(struct siw_qp *qp, const struct ib_send_wr *wr,
 			   const struct ib_send_wr **bad_wr)
 {
-	struct siw_sqe sqe = {};
 	int rv = 0;
 
 	while (wr) {
-		sqe.id = wr->wr_id;
-		sqe.opcode = wr->opcode;
-		rv = siw_sqe_complete(qp, &sqe, 0, SIW_WC_WR_FLUSH_ERR);
+		struct siw_sqe sqe = {};
+
+		switch (wr->opcode) {
+		case IB_WR_RDMA_WRITE:
+			sqe.opcode = SIW_OP_WRITE;
+			break;
+		case IB_WR_RDMA_READ:
+			sqe.opcode = SIW_OP_READ;
+			break;
+		case IB_WR_RDMA_READ_WITH_INV:
+			sqe.opcode = SIW_OP_READ_LOCAL_INV;
+			break;
+		case IB_WR_SEND:
+			sqe.opcode = SIW_OP_SEND;
+			break;
+		case IB_WR_SEND_WITH_IMM:
+			sqe.opcode = SIW_OP_SEND_WITH_IMM;
+			break;
+		case IB_WR_SEND_WITH_INV:
+			sqe.opcode = SIW_OP_SEND_REMOTE_INV;
+			break;
+		case IB_WR_LOCAL_INV:
+			sqe.opcode = SIW_OP_INVAL_STAG;
+			break;
+		case IB_WR_REG_MR:
+			sqe.opcode = SIW_OP_REG_MR;
+			break;
+		default:
+			rv = -EOPNOTSUPP;
+			break;
+		}
+		if (!rv) {
+			sqe.id = wr->wr_id;
+			rv = siw_sqe_complete(qp, &sqe, 0,
+					      SIW_WC_WR_FLUSH_ERR);
+		}
 		if (rv) {
 			if (bad_wr)
 				*bad_wr = wr;
-- 
2.32.0