[PATCH v2 1/3] media: imx-jpeg: Enhance error handling in buffer allocation

[ming.qian@oss.nxp.com]

From: Ming Qian <ming.qian@oss.nxp.com>

In function mxc_jpeg_alloc_slot_data, driver will allocate some dma
buffer, but only return error if certain allocation failed.

Without cleanup the allocation failure, the next time it will return
success directly, but let some buffer be uninitialized.
It may result in accessing a null pointer.

Clean up if error occurs in the allocation.

Fixes: 2db16c6ed72c ("media: imx-jpeg: Add V4L2 driver for i.MX8 JPEG Encoder/Decoder")
Signed-off-by: Ming Qian <ming.qian@oss.nxp.com>
---
v2
- Add the Fixes tag

 .../media/platform/nxp/imx-jpeg/mxc-jpeg.c    | 47 +++++++++++--------
 1 file changed, 27 insertions(+), 20 deletions(-)

diff --git a/drivers/media/platform/nxp/imx-jpeg/mxc-jpeg.c b/drivers/media/platform/nxp/imx-jpeg/mxc-jpeg.c
index 0e6ee997284b..12661c177f5a 100644
--- a/drivers/media/platform/nxp/imx-jpeg/mxc-jpeg.c
+++ b/drivers/media/platform/nxp/imx-jpeg/mxc-jpeg.c
@@ -752,6 +752,32 @@ static int mxc_get_free_slot(struct mxc_jpeg_slot_data *slot_data)
 	return -1;
 }
 
+static void mxc_jpeg_free_slot_data(struct mxc_jpeg_dev *jpeg)
+{
+	/* free descriptor for decoding/encoding phase */
+	dma_free_coherent(jpeg->dev, sizeof(struct mxc_jpeg_desc),
+			  jpeg->slot_data.desc,
+			  jpeg->slot_data.desc_handle);
+	jpeg->slot_data.desc = NULL;
+	jpeg->slot_data.desc_handle = 0;
+
+	/* free descriptor for encoder configuration phase / decoder DHT */
+	dma_free_coherent(jpeg->dev, sizeof(struct mxc_jpeg_desc),
+			  jpeg->slot_data.cfg_desc,
+			  jpeg->slot_data.cfg_desc_handle);
+	jpeg->slot_data.cfg_desc_handle = 0;
+	jpeg->slot_data.cfg_desc = NULL;
+
+	/* free configuration stream */
+	dma_free_coherent(jpeg->dev, MXC_JPEG_MAX_CFG_STREAM,
+			  jpeg->slot_data.cfg_stream_vaddr,
+			  jpeg->slot_data.cfg_stream_handle);
+	jpeg->slot_data.cfg_stream_vaddr = NULL;
+	jpeg->slot_data.cfg_stream_handle = 0;
+
+	jpeg->slot_data.used = false;
+}
+
 static bool mxc_jpeg_alloc_slot_data(struct mxc_jpeg_dev *jpeg)
 {
 	struct mxc_jpeg_desc *desc;
@@ -794,30 +820,11 @@ static bool mxc_jpeg_alloc_slot_data(struct mxc_jpeg_dev *jpeg)
 	return true;
 err:
 	dev_err(jpeg->dev, "Could not allocate descriptors for slot %d", jpeg->slot_data.slot);
+	mxc_jpeg_free_slot_data(jpeg);
 
 	return false;
 }
 
-static void mxc_jpeg_free_slot_data(struct mxc_jpeg_dev *jpeg)
-{
-	/* free descriptor for decoding/encoding phase */
-	dma_free_coherent(jpeg->dev, sizeof(struct mxc_jpeg_desc),
-			  jpeg->slot_data.desc,
-			  jpeg->slot_data.desc_handle);
-
-	/* free descriptor for encoder configuration phase / decoder DHT */
-	dma_free_coherent(jpeg->dev, sizeof(struct mxc_jpeg_desc),
-			  jpeg->slot_data.cfg_desc,
-			  jpeg->slot_data.cfg_desc_handle);
-
-	/* free configuration stream */
-	dma_free_coherent(jpeg->dev, MXC_JPEG_MAX_CFG_STREAM,
-			  jpeg->slot_data.cfg_stream_vaddr,
-			  jpeg->slot_data.cfg_stream_handle);
-
-	jpeg->slot_data.used = false;
-}
-
 static void mxc_jpeg_check_and_set_last_buffer(struct mxc_jpeg_ctx *ctx,
 					       struct vb2_v4l2_buffer *src_buf,
 					       struct vb2_v4l2_buffer *dst_buf)
-- 
2.43.0-rc1