dmatest: fix use after free in dmatest_exit

dmatest_cleanup_chanel will free dtc, so grab ->chan before it goes away
and use it to do the release.

Reported-by: Thierry Reding <thierry.reding@avionic-design.de>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

diff --git a/drivers/dma/dmatest.c b/drivers/dma/dmatest.c
index 732fa1ec36ab3ae885b784ca1ea5bb863cc3c58f..e190d8b30700c40858fceb83afa05f49d9ce8d2e 100644 (file)
--- a/drivers/dma/dmatest.c
+++ b/drivers/dma/dmatest.c
@@ -430,13 +430,15 @@ late_initcall(dmatest_init);
 static void __exit dmatest_exit(void)
 {
        struct dmatest_chan *dtc, *_dtc;
+       struct dma_chan *chan;
 
        list_for_each_entry_safe(dtc, _dtc, &dmatest_channels, node) {
                list_del(&dtc->node);
+               chan = dtc->chan;
                dmatest_cleanup_channel(dtc);
                pr_debug("dmatest: dropped channel %s\n",
-                        dma_chan_name(dtc->chan));
-               dma_release_channel(dtc->chan);
+                        dma_chan_name(chan));
+               dma_release_channel(chan);
        }
 }
 module_exit(dmatest_exit);