IB/iser: Fix use after free in iser_snd_completion()

We use "tx_desc" again after we free it.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Or Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>

1 files changed, 2 insertions, 1 deletions

diff --git a/drivers/infiniband/ulp/iser/iser_initiator.c b/drivers/infiniband/ulp/iser/iser_initiator.c
index 538822684d5b..334f34b1cd46 100644
--- a/drivers/infiniband/ulp/iser/iser_initiator.c
+++ b/drivers/infiniband/ulp/iser/iser_initiator.c
@@ -610,11 +610,12 @@ void iser_snd_completion(struct iser_tx_desc *tx_desc,
                 ib_dma_unmap_single(device->ib_device, tx_desc->dma_addr,
                                         ISER_HEADERS_LEN, DMA_TO_DEVICE);
                 kmem_cache_free(ig.desc_cache, tx_desc);
+                tx_desc = NULL;
         }
 
         atomic_dec(&ib_conn->post_send_buf_count);
 
-        if (tx_desc->type == ISCSI_TX_CONTROL) {
+        if (tx_desc && tx_desc->type == ISCSI_TX_CONTROL) {
                 /* this arithmetic is legal by libiscsi dd_data allocation */
                 task = (void *) ((long)(void *)tx_desc -
                                   sizeof(struct iscsi_task));