[FFmpeg-devel] [PATCH 3/5] avformat/webmdashenc: Remove possibility of infinite loop
Andreas Rheinhardt
andreas.rheinhardt at gmail.com
Mon May 18 06:30:31 EEST 2020
The WebM DASH manifest muxer uses a loop to parse the adaptation_sets
string (which is given by the user and governs which AVStreams are
mapped to what adaptation set) and the very beginning of this loop is
"if (*p == ' ') continue;". This of course leads to an infinite loop if
the condition is true. It is true if e.g. the string begins with ' ' or
if there are more than one ' ' between different adaptation set groups.
To fix this, the parsing process has been modified to consume the space
if it is at a place where it can legitimately occur, i.e. when a new
adaptation set group is expected. The latter restriction implies that an
error is returned if a space exists where none is allowed to exist.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt at gmail.com>
---
libavformat/webmdashenc.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/libavformat/webmdashenc.c b/libavformat/webmdashenc.c
index 250c8ca3ad..fd07b3e34a 100644
--- a/libavformat/webmdashenc.c
+++ b/libavformat/webmdashenc.c
@@ -438,9 +438,10 @@ static int parse_adaptation_sets(AVFormatContext *s)
// syntax id=0,streams=0,1,2 id=1,streams=3,4 and so on
state = new_set;
while (p < w->adaptation_sets + strlen(w->adaptation_sets)) {
- if (*p == ' ')
+ if (state == new_set && *p == ' ') {
+ p++;
continue;
- else if (state == new_set && !strncmp(p, "id=", 3)) {
+ } else if (state == new_set && !strncmp(p, "id=", 3)) {
void *mem = av_realloc(w->as, sizeof(*w->as) * (w->nb_as + 1));
const char *comma;
if (mem == NULL)
--
2.20.1
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