Merge tag 'dmaengine-fix-4.16-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/vkoul/slave-dma

Pull dmaengine fix from Vinod Koul:
 "One small fix for stm32-dmamux fixing buffer overflow"

* tag 'dmaengine-fix-4.16-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/vkoul/slave-dma:
  dmaengine: stm32-dmamux: fix a potential buffer overflow

1 files changed, 6 insertions, 3 deletions

diff --git a/drivers/dma/stm32-dmamux.c b/drivers/dma/stm32-dmamux.c
index 4dbb30cf94ac..b922db90939a 100644
--- a/drivers/dma/stm32-dmamux.c
+++ b/drivers/dma/stm32-dmamux.c
@@ -118,14 +118,15 @@ static void *stm32_dmamux_route_allocate(struct of_phandle_args *dma_spec,
         spin_lock_irqsave(&dmamux->lock, flags);
         mux->chan_id = find_first_zero_bit(dmamux->dma_inuse,
                                            dmamux->dma_requests);
-        set_bit(mux->chan_id, dmamux->dma_inuse);
-        spin_unlock_irqrestore(&dmamux->lock, flags);
 
         if (mux->chan_id == dmamux->dma_requests) {
+                spin_unlock_irqrestore(&dmamux->lock, flags);
                 dev_err(&pdev->dev, "Run out of free DMA requests\n");
                 ret = -ENOMEM;
-                goto error;
+                goto error_chan_id;
         }
+        set_bit(mux->chan_id, dmamux->dma_inuse);
+        spin_unlock_irqrestore(&dmamux->lock, flags);
 
         /* Look for DMA Master */
         for (i = 1, min = 0, max = dmamux->dma_reqs[i];
@@ -173,6 +174,8 @@ static void *stm32_dmamux_route_allocate(struct of_phandle_args *dma_spec,
 
 error:
         clear_bit(mux->chan_id, dmamux->dma_inuse);
+
+error_chan_id:
         kfree(mux);
         return ERR_PTR(ret);
 }