[PATCH] net: mvneta: fix double free of txq->buf

[trix]

From: Tom Rix <t...@redhat.com>

clang static analysis reports this problem:

drivers/net/ethernet/marvell/mvneta.c:3465:2: warning:
  Attempt to free released memory
        kfree(txq->buf);
        ^~~~~~~~~~~~~~~

When mvneta_txq_sw_init() fails to alloc txq->tso_hdrs,
it frees without poisoning txq->buf.  The error is caught
in the mvneta_setup_txqs() caller which handles the error
by cleaning up all of the txqs with a call to
mvneta_txq_sw_deinit which also frees txq->buf.

Since mvneta_txq_sw_deinit is a general cleaner, all of the
partial cleaning in mvneta_txq_sw_deinit()'s error handling
is not needed.

Fixes: 2adb719d74f6 ("net: mvneta: Implement software TSO")
Signed-off-by: Tom Rix <t...@redhat.com>
---
 drivers/net/ethernet/marvell/mvneta.c | 13 ++-----------
 1 file changed, 2 insertions(+), 11 deletions(-)

diff --git a/drivers/net/ethernet/marvell/mvneta.c 
b/drivers/net/ethernet/marvell/mvneta.c
index d095718355d3..54b0bf574c05 100644
--- a/drivers/net/ethernet/marvell/mvneta.c
+++ b/drivers/net/ethernet/marvell/mvneta.c
@@ -3397,24 +3397,15 @@ static int mvneta_txq_sw_init(struct mvneta_port *pp,
        txq->last_desc = txq->size - 1;
 
        txq->buf = kmalloc_array(txq->size, sizeof(*txq->buf), GFP_KERNEL);
-       if (!txq->buf) {
-               dma_free_coherent(pp->dev->dev.parent,
-                                 txq->size * MVNETA_DESC_ALIGNED_SIZE,
-                                 txq->descs, txq->descs_phys);
+       if (!txq->buf)
                return -ENOMEM;
-       }
 
        /* Allocate DMA buffers for TSO MAC/IP/TCP headers */
        txq->tso_hdrs = dma_alloc_coherent(pp->dev->dev.parent,
                                           txq->size * TSO_HEADER_SIZE,
                                           &txq->tso_hdrs_phys, GFP_KERNEL);
-       if (!txq->tso_hdrs) {
-               kfree(txq->buf);
-               dma_free_coherent(pp->dev->dev.parent,
-                                 txq->size * MVNETA_DESC_ALIGNED_SIZE,
-                                 txq->descs, txq->descs_phys);
+       if (!txq->tso_hdrs)
                return -ENOMEM;
-       }
 
        /* Setup XPS mapping */
        if (txq_number > 1)
-- 
2.18.1