[ 116/218] dmaengine: at_hdmac: check that each sg data length is non-null

[Greg Kroah-Hartman]

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

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

From: Nicolas Ferre <nicolas.ferre@xxxxxxxxx>

commit c456797681db814f4f5b36909e8e94047bf53d9c upstream.

Avoid the construction of a malformed DMA request sent to
the DMA controller.
Log message is for debug only because this condition is unlikely to
append and may only trigger at driver development time.

Signed-off-by: Nicolas Ferre <nicolas.ferre@xxxxxxxxx>
Signed-off-by: Vinod Koul <vinod.koul@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/dma/at_hdmac.c |   11 +++++++++++
 1 file changed, 11 insertions(+)

--- a/drivers/dma/at_hdmac.c
+++ b/drivers/dma/at_hdmac.c
@@ -691,6 +691,11 @@ atc_prep_slave_sg(struct dma_chan *chan,
 
 			mem = sg_dma_address(sg);
 			len = sg_dma_len(sg);
+			if (unlikely(!len)) {
+				dev_dbg(chan2dev(chan),
+					"prep_slave_sg: sg(%d) data length is zero\n", i);
+				goto err;
+			}
 			mem_width = 2;
 			if (unlikely(mem & 3 || len & 3))
 				mem_width = 0;
@@ -726,6 +731,11 @@ atc_prep_slave_sg(struct dma_chan *chan,
 
 			mem = sg_dma_address(sg);
 			len = sg_dma_len(sg);
+			if (unlikely(!len)) {
+				dev_dbg(chan2dev(chan),
+					"prep_slave_sg: sg(%d) data length is zero\n", i);
+				goto err;
+			}
 			mem_width = 2;
 			if (unlikely(mem & 3 || len & 3))
 				mem_width = 0;
@@ -759,6 +769,7 @@ atc_prep_slave_sg(struct dma_chan *chan,
 
 err_desc_get:
 	dev_err(chan2dev(chan), "not enough descriptors available\n");
+err:
 	atc_desc_put(atchan, first);
 	return NULL;
 }


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