[PATCH 1/2] dmaengine: ti: k3-udma: Fix NULL pointer dereference error for BCDMA

From: Kishon Vijay Abraham I
Date: Wed Oct 27 2021 - 01:53:11 EST


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@xxxxxx>
---
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