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From: Pan Bian <bianpan2016@163.com>
To: Dan Williams <dan.j.williams@intel.com>,
	Vinod Koul <vkoul@kernel.org>, Maxime Ripard <mripard@kernel.org>,
	Chen-Yu Tsai <wens@csie.org>
Cc: dmaengine@vger.kernel.org, Pan Bian <bianpan2016@163.com>,
	linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org
Subject: [PATCH] dmaengine: sun6i: Fix use after free
Date: Thu,  7 Nov 2019 19:26:53 +0800	[thread overview]
Message-ID: <1573126013-17609-1-git-send-email-bianpan2016@163.com> (raw)

The members in the LLI list is released in an incorrect way. Read and
store the next member before releasing it to avoid accessing the freed
memory.

Fixes: a90e173f3faf ("dmaengine: sun6i: Add cyclic capability")

Signed-off-by: Pan Bian <bianpan2016@163.com>
---
 drivers/dma/sun6i-dma.c | 20 ++++++++++++++------
 1 file changed, 14 insertions(+), 6 deletions(-)

diff --git a/drivers/dma/sun6i-dma.c b/drivers/dma/sun6i-dma.c
index 06cd7f867f7c..096aad7e75bb 100644
--- a/drivers/dma/sun6i-dma.c
+++ b/drivers/dma/sun6i-dma.c
@@ -687,7 +687,7 @@ static struct dma_async_tx_descriptor *sun6i_dma_prep_slave_sg(
 	struct sun6i_dma_dev *sdev = to_sun6i_dma_dev(chan->device);
 	struct sun6i_vchan *vchan = to_sun6i_vchan(chan);
 	struct dma_slave_config *sconfig = &vchan->cfg;
-	struct sun6i_dma_lli *v_lli, *prev = NULL;
+	struct sun6i_dma_lli *v_lli, *next, *prev = NULL;
 	struct sun6i_desc *txd;
 	struct scatterlist *sg;
 	dma_addr_t p_lli;
@@ -752,8 +752,12 @@ static struct dma_async_tx_descriptor *sun6i_dma_prep_slave_sg(
 	return vchan_tx_prep(&vchan->vc, &txd->vd, flags);
 
 err_lli_free:
-	for (prev = txd->v_lli; prev; prev = prev->v_lli_next)
-		dma_pool_free(sdev->pool, prev, virt_to_phys(prev));
+	v_lli = txd->v_lli;
+	while (v_lli) {
+		next = v_lli->v_lli_next;
+		dma_pool_free(sdev->pool, v_lli, virt_to_phys(v_lli));
+		v_lli = next;
+	}
 	kfree(txd);
 	return NULL;
 }
@@ -769,7 +773,7 @@ static struct dma_async_tx_descriptor *sun6i_dma_prep_dma_cyclic(
 	struct sun6i_dma_dev *sdev = to_sun6i_dma_dev(chan->device);
 	struct sun6i_vchan *vchan = to_sun6i_vchan(chan);
 	struct dma_slave_config *sconfig = &vchan->cfg;
-	struct sun6i_dma_lli *v_lli, *prev = NULL;
+	struct sun6i_dma_lli *v_lli, *next, *prev = NULL;
 	struct sun6i_desc *txd;
 	dma_addr_t p_lli;
 	u32 lli_cfg;
@@ -820,8 +824,12 @@ static struct dma_async_tx_descriptor *sun6i_dma_prep_dma_cyclic(
 	return vchan_tx_prep(&vchan->vc, &txd->vd, flags);
 
 err_lli_free:
-	for (prev = txd->v_lli; prev; prev = prev->v_lli_next)
-		dma_pool_free(sdev->pool, prev, virt_to_phys(prev));
+	v_lli = txd->v_lli;
+	while (v_lli) {
+		next = v_lli->v_lli_next;
+		dma_pool_free(sdev->pool, v_lli, virt_to_phys(v_lli));
+		v_lli = next;
+	}
 	kfree(txd);
 	return NULL;
 }
-- 
2.7.4


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             reply	other threads:[~2019-11-07 11:27 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-07 11:26 Pan Bian [this message]
2019-11-14  6:45 ` [PATCH] dmaengine: sun6i: Fix use after free Vinod Koul

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