[PATCH v3] dmaengine: ti: k3-udma-glue: fix NULL dereference in k3_udma_glue_release_rx_chn()

[Alexander.Chesnokov]

From: Alexander Chesnokov <Alexander.Chesnokov@xxxxxxxxxxxxx>

If devm_kcalloc() for rx_chn->flows fails in a channel request function,
the error path calls k3_udma_glue_release_rx_chn(), which dereferences
the NULL rx_chn->flows pointer in k3_udma_glue_release_rx_flow().

Skip the flow release loop in k3_udma_glue_release_rx_chn() when
rx_chn->flows is not allocated.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Fixes: d70241913413 ("dmaengine: ti: k3-udma: Add glue layer for non DMAengine users")
Cc: stable@xxxxxxxxxxxxxxx
Reported-by: Pavel Zhigulin <Pavel.Zhigulin@xxxxxxxxxxxxx>
Signed-off-by: Alexander Chesnokov <Alexander.Chesnokov@xxxxxxxxxxxxx>
---

v3: guard the flow release loop in k3_udma_glue_release_rx_chn() instead
of reordering the flow_num assignment. Covers all error paths in both
request functions.
v2: https://lore.kernel.org/all/20251006124258.1132312-1-Pavel.Zhigulin@xxxxxxxxxxxxx/

 drivers/dma/ti/k3-udma-glue.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/dma/ti/k3-udma-glue.c b/drivers/dma/ti/k3-udma-glue.c
index 4f1aeb81e9c7..a739e60b0764 100644
--- a/drivers/dma/ti/k3-udma-glue.c
+++ b/drivers/dma/ti/k3-udma-glue.c
@@ -1103,8 +1103,9 @@ void k3_udma_glue_release_rx_chn(struct k3_udma_glue_rx_channel *rx_chn)
 		rx_chn->psil_paired = false;
 	}
 
-	for (i = 0; i < rx_chn->flow_num; i++)
-		k3_udma_glue_release_rx_flow(rx_chn, i);
+	if (rx_chn->flows)
+		for (i = 0; i < rx_chn->flow_num; i++)
+			k3_udma_glue_release_rx_flow(rx_chn, i);
 
 	if (xudma_rflow_is_gp(rx_chn->common.udmax, rx_chn->flow_id_base))
 		xudma_free_gp_rflow_range(rx_chn->common.udmax,
-- 
2.43.0