[dpdk-dev] [PATCH] net/vmxnet3: fix dereference before null check

[Michal Jastrzebski <michalx.k.jastrzebski@intel.com>]

From: Tomasz Kulasek <tomaszx.kulasek@intel.com>

Coverity error:

check_after_deref: Null-checking rq suggests that it may be null, but it
                   has already been dereferenced on all paths leading to
                   the check.

This patch moves NULL checking of "rq" at the very beginning of the path
before any dereference.

Coverity issue: 143468
Fixes: 5aecdc17a97d ("vmxnet3: fix stop/restart")
Cc: yongwang@vmware.com
Cc: stable@dpdk.org

Signed-off-by: Tomasz Kulasek <tomaszx.kulasek@intel.com>
---
 drivers/net/vmxnet3/vmxnet3_rxtx.c | 17 ++++++++---------
 1 file changed, 8 insertions(+), 9 deletions(-)

diff --git a/drivers/net/vmxnet3/vmxnet3_rxtx.c b/drivers/net/vmxnet3/vmxnet3_rxtx.c
index d9cf437..4fcceb4 100644
--- a/drivers/net/vmxnet3/vmxnet3_rxtx.c
+++ b/drivers/net/vmxnet3/vmxnet3_rxtx.c
@@ -259,17 +259,16 @@
 {
 	int i;
 	vmxnet3_rx_queue_t *rq = rxq;
-	struct vmxnet3_hw *hw = rq->hw;
 	struct vmxnet3_cmd_ring *ring0, *ring1;
 	struct vmxnet3_comp_ring *comp_ring;
-	struct vmxnet3_rx_data_ring *data_ring = &rq->data_ring;
 	int size;
 
-	if (rq != NULL) {
-		/* Release both the cmd_rings mbufs */
-		for (i = 0; i < VMXNET3_RX_CMDRING_SIZE; i++)
-			vmxnet3_rx_cmd_ring_release_mbufs(&rq->cmd_ring[i]);
-	}
+	if (rq == NULL)
+		return;
+
+	/* Release both the cmd_rings mbufs */
+	for (i = 0; i < VMXNET3_RX_CMDRING_SIZE; i++)
+		vmxnet3_rx_cmd_ring_release_mbufs(&rq->cmd_ring[i]);
 
 	ring0 = &rq->cmd_ring[0];
 	ring1 = &rq->cmd_ring[1];
@@ -287,8 +286,8 @@
 
 	size = sizeof(struct Vmxnet3_RxDesc) * (ring0->size + ring1->size);
 	size += sizeof(struct Vmxnet3_RxCompDesc) * comp_ring->size;
-	if (VMXNET3_VERSION_GE_3(hw) && rq->data_desc_size)
-		size += rq->data_desc_size * data_ring->size;
+	if (VMXNET3_VERSION_GE_3(rq->hw) && rq->data_desc_size)
+		size += rq->data_desc_size * rq->data_ring.size;
 
 	memset(ring0->base, 0, size);
 }
-- 
1.9.1