[FFmpeg-cvslog] avdevice/dshow: prevent NULL access

[Diederick Niehorster]

ffmpeg | branch: master | Diederick Niehorster <dcnieho at gmail.com> | Tue Dec 21 14:53:26 2021 +0100| [7b21841ce45ef4ab486c3c94a714345b878a70fd] | committer: Gyan Doshi

avdevice/dshow: prevent NULL access

list_options true would crash when both a video and an audio device were
specified as input. Crash would occur on line 784 because
ctx->device_unique_name[otherDevType] would be NULL

Signed-off-by: Diederick Niehorster <dcnieho at gmail.com>
Reviewed-by: Roger Pack <rogerdpack2 at gmail.com>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=7b21841ce45ef4ab486c3c94a714345b878a70fd
---

 libavdevice/dshow.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/libavdevice/dshow.c b/libavdevice/dshow.c
index ef78781865..cc0bef0474 100644
--- a/libavdevice/dshow.c
+++ b/libavdevice/dshow.c
@@ -708,9 +708,9 @@ dshow_list_device_options(AVFormatContext *avctx, ICreateDevEnum *devenum,
     if ((r = dshow_cycle_devices(avctx, devenum, devtype, sourcetype, &device_filter, &device_unique_name)) < 0)
         return r;
     ctx->device_filter[devtype] = device_filter;
+    ctx->device_unique_name[devtype] = device_unique_name;
     if ((r = dshow_cycle_pins(avctx, devtype, sourcetype, device_filter, NULL)) < 0)
         return r;
-    av_freep(&device_unique_name);
     return 0;
 }
 
@@ -1143,6 +1143,7 @@ static int dshow_read_header(AVFormatContext *avctx)
                 }
             }
         }
+        // don't exit yet, allow it to list crossbar options in dshow_open_device
     }
     if (ctx->device_name[VideoDevice]) {
         if ((r = dshow_open_device(avctx, devenum, VideoDevice, VideoSourceDevice)) < 0 ||