[PATCH] dmaengine: at_xdmac: avoid null_prt_deref in at_xdmac_prep_dma_memset

[Chen Ridong]

From: Chen Ridong <chenridong at huawei.com>

The at_xdmac_memset_create_desc may return NULL, which will lead to a
null pointer dereference. For example, the len input is error, or the
atchan->free_descs_list is empty and memory is exhausted. Therefore, add
check to avoid this.

Fixes: b206d9a23ac7 ("dmaengine: xdmac: Add memset support")
Signed-off-by: Chen Ridong <chenridong at huawei.com>
---
 drivers/dma/at_xdmac.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/dma/at_xdmac.c b/drivers/dma/at_xdmac.c
index 299396121e6d..e847ad66dc0b 100644
--- a/drivers/dma/at_xdmac.c
+++ b/drivers/dma/at_xdmac.c
@@ -1363,6 +1363,8 @@ at_xdmac_prep_dma_memset(struct dma_chan *chan, dma_addr_t dest, int value,
 		return NULL;
 
 	desc = at_xdmac_memset_create_desc(chan, atchan, dest, len, value);
+	if (!desc)
+		return NULL;
 	list_add_tail(&desc->desc_node, &desc->descs_list);
 
 	desc->tx_dma_desc.cookie = -EBUSY;
-- 
2.34.1