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From:   Kishon Vijay Abraham I <kishon@ti.com>
To:     Peter Ujfalusi <peter.ujfalusi@gmail.com>,
        Vinod Koul <vkoul@kernel.org>
CC:     <dmaengine@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        Vignesh Raghavendra <vigneshr@ti.com>,
        Kishon Vijay Abraham I <kishon@ti.com>
Subject: [PATCH v2 1/2] dmaengine: ti: k3-udma: Fix NULL pointer dereference error for BCDMA
Date:   Wed, 27 Oct 2021 11:22:53 +0530
Message-ID: <20211027055254.10912-4-kishon@ti.com>
In-Reply-To: <20211027055254.10912-1-kishon@ti.com>
References: <20211027055254.10912-1-kishon@ti.com>
MIME-Version: 1.0
Content-Type: text/plain
Precedence: bulk

bcdma_get_*() checks if bchan is already allocated by checking if it
has a NON NULL value. For the error cases, bchan will have error value
and bcdma_get_*() considers this as already allocated (PASS) since the
error values are NON NULL. This results in NULL pointer dereference
error while de-referencing bchan.

Reset the value of bchan to NULL if the allocation actually fails.

Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
---
 drivers/dma/ti/k3-udma.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/dma/ti/k3-udma.c b/drivers/dma/ti/k3-udma.c
index a35858610780..14ae28830871 100644
--- a/drivers/dma/ti/k3-udma.c
+++ b/drivers/dma/ti/k3-udma.c
@@ -1348,6 +1348,7 @@ static int bcdma_get_bchan(struct udma_chan *uc)
 {
 	struct udma_dev *ud = uc->ud;
 	enum udma_tp_level tpl;
+	int ret;
 
 	if (uc->bchan) {
 		dev_dbg(ud->dev, "chan%d: already have bchan%d allocated\n",
@@ -1365,8 +1366,11 @@ static int bcdma_get_bchan(struct udma_chan *uc)
 		tpl = ud->bchan_tpl.levels - 1;
 
 	uc->bchan = __udma_reserve_bchan(ud, tpl, -1);
-	if (IS_ERR(uc->bchan))
-		return PTR_ERR(uc->bchan);
+	if (IS_ERR(uc->bchan)) {
+		ret = PTR_ERR(uc->bchan);
+		uc->bchan = NULL;
+		return ret;
+	}
 
 	uc->tchan = uc->bchan;
 
-- 
2.17.1