IB/iser: use after free in iser_snd_completion()

We use "tx_desc" again after we free it.

Signed-off-by Dan Carpenter <[email protected]>

drivers/infiniband/ulp/iser/iser_initiator.c +2 -2

index 538822684d5b..334f34b1cd46 100644
@@ -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));
--

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Quoted 1 line · Dan Carpenter

We use "tx_desc" again after we free it.

yep, this is legacy code which isn't much of use over the last years and hence the bug went in unnoticed