linux-kernel - [PATCH 5.14 800/849] dmaengine: ti: k3-udma: Set bchan to NULL if a channel request fail

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Date:   Mon, 15 Nov 2021 18:04:43 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Peter Ujfalusi <peter.ujfalusi@...il.com>,
        Kishon Vijay Abraham I <kishon@...com>,
        Vinod Koul <vkoul@...nel.org>
Subject: [PATCH 5.14 800/849] dmaengine: ti: k3-udma: Set bchan to NULL if a channel request fail

From: Kishon Vijay Abraham I <kishon@...com>

commit 5c6c6d60e4b489308ae4da8424c869f7cc53cd12 upstream.

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 a channel request fails.

CC: stable@...r.kernel.org
Acked-by: Peter Ujfalusi <peter.ujfalusi@...il.com>
Signed-off-by: Kishon Vijay Abraham I <kishon@...com>
Link: https://lore.kernel.org/r/20211031032411.27235-2-kishon@ti.com
Signed-off-by: Vinod Koul <vkoul@...nel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/dma/ti/k3-udma.c |    8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

--- 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_c
 {
 	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_c
 		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;