From 77ebc64f40717b8501793b5f5ee717a141e62e8e Mon Sep 17 00:00:00 2001 From: Linus Walleij Date: Sun, 27 Sep 2026 11:03:31 +0200 Subject: [PATCH] dmaengine: ste_dma40: Reject direction changes after allocation Logical channel allocation uses the configured direction to select the source or destination allocation mask, derive the logical channel number, and choose the LCPA location. d40_set_runtime_config_write() nevertheless overwrites the configured direction when a transfer is prepared for the opposite direction. d40_free_dma() then clears the wrong allocation mask, leaking the original resource and potentially releasing one used by another client. Reject directions that differ from the direction used during allocation and propagate runtime configuration errors to callers. Skip slave runtime configuration for memcpy transfers, which also use d40_prep_sg() but do not require it. Fixes: 95e1400fa131 ("DMAENGINE: add runtime slave config to DMA40 v3") Reported-by: sashiko-bot@kernel.org Closes: https://lore.kernel.org/dmaengine/20260618051539.15E201F000E9@smtp.kernel.org/ Assisted-by: LLM Reviewed-by: Frank Li Signed-off-by: Linus Walleij Link: https://patch.msgid.link/20260927-dma40-fixes-v7-18-89f595e8851d@kernel.org Signed-off-by: Vinod Koul --- drivers/dma/ste_dma40.c | 29 ++++++++++++++--------------- 1 file changed, 14 insertions(+), 15 deletions(-) diff --git a/drivers/dma/ste_dma40.c b/drivers/dma/ste_dma40.c index 0c183a34edea..2c818fadeb2a 100644 --- a/drivers/dma/ste_dma40.c +++ b/drivers/dma/ste_dma40.c @@ -2405,7 +2405,13 @@ d40_prep_sg(struct dma_chan *dchan, struct scatterlist *sg_src, return NULL; } - d40_set_runtime_config_write(dchan, &chan->slave_config, direction); + if (direction != DMA_MEM_TO_MEM) { + ret = d40_set_runtime_config_write(dchan, + &chan->slave_config, + direction); + if (ret) + return NULL; + } spin_lock_irqsave(&chan->lock, flags); @@ -2881,6 +2887,13 @@ static int d40_set_runtime_config_write(struct dma_chan *chan, return -EINVAL; } + if (direction != cfg->dir) { + chan_err(d40c, + "transfer direction %d differs from allocated direction %d\n", + direction, cfg->dir); + return -EINVAL; + } + src_addr_width = config->src_addr_width; src_maxburst = config->src_maxburst; dst_addr_width = config->dst_addr_width; @@ -2889,13 +2902,6 @@ static int d40_set_runtime_config_write(struct dma_chan *chan, if (direction == DMA_DEV_TO_MEM) { config_addr = config->src_addr; - if (cfg->dir != DMA_DEV_TO_MEM) - dev_dbg(d40c->base->dev, - "channel was not configured for peripheral " - "to memory transfer (%d) overriding\n", - cfg->dir); - cfg->dir = DMA_DEV_TO_MEM; - /* Configure the memory side */ if (dst_addr_width == DMA_SLAVE_BUSWIDTH_UNDEFINED) dst_addr_width = src_addr_width; @@ -2905,13 +2911,6 @@ static int d40_set_runtime_config_write(struct dma_chan *chan, } else if (direction == DMA_MEM_TO_DEV) { config_addr = config->dst_addr; - if (cfg->dir != DMA_MEM_TO_DEV) - dev_dbg(d40c->base->dev, - "channel was not configured for memory " - "to peripheral transfer (%d) overriding\n", - cfg->dir); - cfg->dir = DMA_MEM_TO_DEV; - /* Configure the memory side */ if (src_addr_width == DMA_SLAVE_BUSWIDTH_UNDEFINED) src_addr_width = dst_addr_width;