[PATCH v4 17/23] dmaengine: ste_dma40: Validate DMA specifier length

[Linus Walleij <linusw@kernel.org>]

The DMA40 binding requires three cells, but d40_xlate() reads args[0],
args[1], and args[2] without checking args_count. A malformed provider node
can specify fewer cells, leaving some of these values uninitialized when
the OF DMA core invokes the translation callback.

Reject specifiers that do not contain exactly three cells before reading
the argument array.

Fixes: fa332de5c6b3 ("dmaengine: ste_dma40: Supply full Device Tree parsing support")
Assisted-by: LLM
Signed-off-by: Linus Walleij <linusw@kernel.org>
---
 drivers/dma/ste_dma40.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/dma/ste_dma40.c b/drivers/dma/ste_dma40.c
index 28e68fbba1a5..7cd063e81328 100644
--- a/drivers/dma/ste_dma40.c
+++ b/drivers/dma/ste_dma40.c
@@ -2516,6 +2516,9 @@ static struct dma_chan *d40_xlate(struct of_phandle_args *dma_spec,
 	dma_cap_mask_t cap;
 	u32 flags;
 
+	if (dma_spec->args_count != 3)
+		return NULL;
+
 	memset(&cfg, 0, sizeof(struct stedma40_chan_cfg));
 
 	dma_cap_zero(cap);

-- 
2.55.0