diff --git a/src/drivers/amd/common/acp_dma.c b/src/drivers/amd/common/acp_dma.c
index bd1e6cba16a2..df68b8bebfb6 100644
--- a/src/drivers/amd/common/acp_dma.c
+++ b/src/drivers/amd/common/acp_dma.c
@@ -314,6 +314,7 @@ static int acp_dma_probe(struct dma *dma)
 				   sizeof(struct acp_dma_chan_data));
 		if (!acp_dma_chan) {
 			rfree(dma->chan);
+			dma->chan = NULL;
 			tr_err(&acpdma_tr, "acp-dma: %d channel %d private data alloc failed",
 			       dma->plat_data.id, channel);
 			return -ENOMEM;
diff --git a/src/drivers/dw/dma.c b/src/drivers/dw/dma.c
index 102cbbe0d7ba..005980454798 100644
--- a/src/drivers/dw/dma.c
+++ b/src/drivers/dw/dma.c
@@ -532,8 +532,6 @@ static int dw_dma_set_config(struct dma_chan_data *channel,
 	/* do we need to realloc descriptors */
 	if (config->elem_array.count != channel->desc_count) {
 
-		channel->desc_count = config->elem_array.count;
-
 		/*
 		 * Allocate descriptors for channel. They must be cache-line
 		 * size aligned to avoid corrupting adjacent memory when
@@ -542,18 +540,25 @@ static int dw_dma_set_config(struct dma_chan_data *channel,
 		 * allocations on Zephyr to always force cache-line size
 		 * alignment.
 		 */
-		if (dw_chan->lli)
-			rfree(dw_chan->lli);
+		rfree(dw_chan->lli);
 
 		dw_chan->lli = rmalloc(SOF_MEM_FLAG_KERNEL | SOF_MEM_FLAG_COHERENT | SOF_MEM_FLAG_DMA,
-				       sizeof(struct dw_lli) * channel->desc_count);
+				       sizeof(struct dw_lli) * config->elem_array.count);
 		if (!dw_chan->lli) {
 			tr_err(&dwdma_tr, "dma %d channel %d lli alloc failed",
 			       channel->dma->plat_data.id,
 			       channel->index);
+			/* allocation failed, so dw_chan->lli is now NULL; reset
+			 * the count to match it so a later config does not
+			 * bzero() a NULL pointer using a stale count
+			 */
+			channel->desc_count = 0;
 			ret = -ENOMEM;
 			goto out;
 		}
+
+		/* only commit the new count once the buffer is allocated */
+		channel->desc_count = config->elem_array.count;
 	}
 
 	/* initialise descriptors */
diff --git a/src/drivers/imx/sdma.c b/src/drivers/imx/sdma.c
index a613f98b40c5..e14db9e6796e 100644
--- a/src/drivers/imx/sdma.c
+++ b/src/drivers/imx/sdma.c
@@ -443,7 +443,7 @@ static void sdma_enable_event(struct dma_chan_data *channel, int eventnum)
 
 	tr_dbg(&sdma_tr, "channel %d, event %d", channel->index, eventnum);
 
-	if (eventnum < 0 || eventnum > SDMA_HWEVENTS_COUNT)
+	if (eventnum < 0 || eventnum >= SDMA_HWEVENTS_COUNT)
 		return; /* No change if request is invalid */
 
 	dma_reg_update_bits(channel->dma, SDMA_CHNENBL(eventnum),
@@ -461,7 +461,7 @@ static void sdma_disable_event(struct dma_chan_data *channel, int eventnum)
 {
 	tr_dbg(&sdma_tr, "channel %d, event %d", channel->index, eventnum);
 
-	if (eventnum < 0 || eventnum > SDMA_HWEVENTS_COUNT)
+	if (eventnum < 0 || eventnum >= SDMA_HWEVENTS_COUNT)
 		return; /* No change if request is invalid */
 
 	dma_reg_update_bits(channel->dma, SDMA_CHNENBL(eventnum),