linux-kernel - [PATCH 4.12 26/52] net/mlx5e: Fix dangling page pointer on DMA mapping error

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Date:   Mon, 18 Sep 2017 11:11:20 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Eran Ben Elisha <eranbe@...lanox.com>,
        Saeed Mahameed <saeedm@...lanox.com>
Subject: [PATCH 4.12 26/52] net/mlx5e: Fix dangling page pointer on DMA mapping error

4.12-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Eran Ben Elisha <eranbe@...lanox.com>


[ Upstream commit 0556ce72ab16156af6c94cdc7964e4310acc97c0 ]

Function mlx5e_dealloc_rx_wqe is using page pointer value as an
indication to valid DMA mapping. In case that the mapping failed, we
released the page but kept the dangling pointer. Store the page pointer
only after the DMA mapping passed to avoid invalid page DMA unmap.

Fixes: bc77b240b3c5 ("net/mlx5e: Add fragmented memory support for RX multi packet WQE")
Signed-off-by: Eran Ben Elisha <eranbe@...lanox.com>
Signed-off-by: Saeed Mahameed <saeedm@...lanox.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/net/ethernet/mellanox/mlx5/core/en_rx.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c
@@ -216,13 +216,13 @@ static inline int mlx5e_page_alloc_mappe
 	if (unlikely(!page))
 		return -ENOMEM;
 
-	dma_info->page = page;
 	dma_info->addr = dma_map_page(rq->pdev, page, 0,
 				      RQ_PAGE_SIZE(rq), rq->buff.map_dir);
 	if (unlikely(dma_mapping_error(rq->pdev, dma_info->addr))) {
 		put_page(page);
 		return -ENOMEM;
 	}
+	dma_info->page = page;
 
 	return 0;
 }