IB/srp: Add memory descriptor array pointer range checking

Although most paths through which a request is submitted check
block layer parameters like the max_segments limit, these are
not checked when an SG_IO or direct I/O request is submitted.
Hence add a range check for the memory descriptor array pointer.
Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/ulp/srp/ib_srp.c

@@ -1277,12 +1277,15 @@ static int srp_map_finish_fmr(struct srp_map_state *state,
 	struct ib_pool_fmr *fmr;
 	u64 io_addr = 0;
 
+	if (state->fmr.next >= state->fmr.end)
+		return -ENOMEM;
+
 	fmr = ib_fmr_pool_map_phys(ch->fmr_pool, state->pages,
 				   state->npages, io_addr);
 	if (IS_ERR(fmr))
 		return PTR_ERR(fmr);
 
-	*state->next_fmr++ = fmr;
+	*state->fmr.next++ = fmr;
 	state->nmdesc++;
 
 	srp_map_desc(state, state->base_dma_addr & ~dev->mr_page_mask,
@@ -1301,6 +1304,9 @@ static int srp_map_finish_fr(struct srp_map_state *state,
 	struct srp_fr_desc *desc;
 	u32 rkey;
 
+	if (state->fr.next >= state->fr.end)
+		return -ENOMEM;
+
 	desc = srp_fr_pool_get(ch->fr_pool);
 	if (!desc)
 		return -ENOMEM;
@@ -1324,7 +1330,7 @@ static int srp_map_finish_fr(struct srp_map_state *state,
 				       IB_ACCESS_REMOTE_WRITE);
 	wr.wr.fast_reg.rkey = desc->mr->lkey;
 
-	*state->next_fr++ = desc;
+	*state->fr.next++ = desc;
 	state->nmdesc++;
 
 	srp_map_desc(state, state->base_dma_addr, state->dma_len,
@@ -1450,10 +1456,12 @@ static int srp_map_sg(struct srp_map_state *state, struct srp_rdma_ch *ch,
 	state->desc	= req->indirect_desc;
 	state->pages	= req->map_page;
 	if (dev->use_fast_reg) {
-		state->next_fr = req->fr_list;
+		state->fr.next = req->fr_list;
+		state->fr.end = req->fr_list + target->cmd_sg_cnt;
 		use_mr = !!ch->fr_pool;
 	} else {
-		state->next_fmr = req->fmr_list;
+		state->fmr.next = req->fmr_list;
+		state->fmr.end = req->fmr_list + target->cmd_sg_cnt;
 		use_mr = !!ch->fmr_pool;
 	}
 

drivers/infiniband/ulp/srp/ib_srp.h

@@ -282,8 +282,14 @@ struct srp_fr_pool {
  */
 struct srp_map_state {
 	union {
-		struct ib_pool_fmr **next_fmr;
-		struct srp_fr_desc **next_fr;
+		struct {
+			struct ib_pool_fmr **next;
+			struct ib_pool_fmr **end;
+		} fmr;
+		struct {
+			struct srp_fr_desc **next;
+			struct srp_fr_desc **end;
+		} fr;
 	};
 	struct srp_direct_buf  *desc;
 	u64		       *pages;