dmaengine: dw-edma: Fix use after free in dw_edma_alloc_chunk()

commit 595a334148449bd1d27cf5d6fcb3b0d718cb1b9f upstream.

If the dw_edma_alloc_burst() function fails then we free "chunk" but
it's still on the "desc->chunk->list" list so it will lead to a use
after free.  Also the "->chunks_alloc" count is incremented when it
shouldn't be.

In current kernels small allocations are guaranteed to succeed and
dw_edma_alloc_burst() can't fail so this will not actually affect
runtime.

Fixes: e63d79d1ffcd ("dmaengine: Add Synopsys eDMA IP core driver")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Gustavo Pimentel <gustavo.pimentel@synopsys.com>
Link: https://lore.kernel.org/r/X9dTBFrUPEvvW7qc@mwanda
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/dma/dw-edma/dw-edma-core.c b/drivers/dma/dw-edma/dw-edma-core.c
index b971505..08d71da 100644 (file)
--- a/drivers/dma/dw-edma/dw-edma-core.c
+++ b/drivers/dma/dw-edma/dw-edma-core.c
@@ -86,12 +86,12 @@ static struct dw_edma_chunk *dw_edma_alloc_chunk(struct dw_edma_desc *desc)
 
        if (desc->chunk) {
                /* Create and add new element into the linked list */
-               desc->chunks_alloc++;
-               list_add_tail(&chunk->list, &desc->chunk->list);
                if (!dw_edma_alloc_burst(chunk)) {
                        kfree(chunk);
                        return NULL;
                }
+               desc->chunks_alloc++;
+               list_add_tail(&chunk->list, &desc->chunk->list);
        } else {
                /* List head */
                chunk->burst = NULL;