avfiltergraph: check for sws opts being non-NULL before using them.

Avoid snprintfing a NULL pointer.

CC: libav-stable@libav.org

diff --git a/libavfilter/avfiltergraph.c b/libavfilter/avfiltergraph.c
index 516617e62bd9e336d4d1fe3517087a69eaa3430a..06b6a101de351ecbc1cb6c2fc1fa808fbfeb6880 100644 (file)
--- a/libavfilter/avfiltergraph.c
+++ b/libavfilter/avfiltergraph.c
@@ -23,6 +23,7 @@
 #include <string.h>
 
 #include "libavutil/avassert.h"
+#include "libavutil/avstring.h"
 #include "libavutil/channel_layout.h"
 #include "libavutil/common.h"
 #include "libavutil/log.h"
@@ -220,7 +221,11 @@ static int query_formats(AVFilterGraph *graph, AVClass *log_ctx)
 
                     snprintf(inst_name, sizeof(inst_name), "auto-inserted scaler %d",
                              scaler_count++);
-                    snprintf(scale_args, sizeof(scale_args), "0:0:%s", graph->scale_sws_opts);
+                    av_strlcpy(scale_args, "0:0", sizeof(scale_args));
+                    if (graph->scale_sws_opts) {
+                        av_strlcat(scale_args, ":", sizeof(scale_args));
+                        av_strlcat(scale_args, graph->scale_sws_opts, sizeof(scale_args));
+                    }
                     if ((ret = avfilter_graph_create_filter(&convert, filter,
                                                             inst_name, scale_args, NULL,
                                                             graph)) < 0)

diff --git a/libavfilter/graphparser.c b/libavfilter/graphparser.c
index ea0a86d51aff5e1e3aa649138b343edf8cce2316..3736639effeabc9825decdbfca520bd8037d2429 100644 (file)
--- a/libavfilter/graphparser.c
+++ b/libavfilter/graphparser.c
@@ -122,7 +122,8 @@ static int create_filter(AVFilterContext **filt_ctx, AVFilterGraph *ctx, int ind
         return ret;
     }
 
-    if (!strcmp(filt_name, "scale") && args && !strstr(args, "flags")) {
+    if (!strcmp(filt_name, "scale") && args && !strstr(args, "flags") &&
+        ctx->scale_sws_opts) {
         snprintf(tmp_args, sizeof(tmp_args), "%s:%s",
                  args, ctx->scale_sws_opts);
         args = tmp_args;