From ced5c5fdb8634d39ca9472a2026b2d2fea16c4e5 Mon Sep 17 00:00:00 2001

From: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>

Date: Mon, 25 Mar 2024 16:54:25 +0100

Subject: [PATCH] fftools/ffmpeg_mux_init: Fix double-free on error

​

MATCH_PER_STREAM_OPT iterates over all options of a given

OptionDef and tests whether they apply to the current stream;

if so, they are set to ost->apad, otherwise, the code errors

out. If no error happens, ost->apad is av_strdup'ed in order

to take ownership of this pointer.

​

But this means that setting it originally was premature,

as it leads to double-frees when an error happens lateron.

This can simply be reproduced with

ffmpeg -filter_complex anullsrc  -apad bar -apad:n baz -f null -

This is a regression since 83ace80bfd80fcdba2c65fa1d554923ea931d5bd.

​

Fix this by using a temporary variable instead of directly

setting ost->apad. Also only strdup the string if it actually

is != NULL.

​

Reviewed-by: Marth64 <marth64@proxyid.net>

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>

---

 fftools/ffmpeg_mux_init.c | 9 +++++++--

 1 file changed, 7 insertions(+), 2 deletions(-)

​

diff --git a/fftools/ffmpeg_mux_init.c b/fftools/ffmpeg_mux_init.c

index 818d76acda..d3d7d022ff 100644

--- a/fftools/ffmpeg_mux_init.c

+++ b/fftools/ffmpeg_mux_init.c

@@ -845,6 +845,7 @@

         int channels = 0;

         char *layout = NULL;

         char *sample_fmt = NULL;

+        const char *apad = NULL;

​

         MATCH_PER_STREAM_OPT(audio_channels, i, channels, oc, st);

         if (channels) {

@@ -882,8 +883,12 @@

​

         MATCH_PER_STREAM_OPT(audio_sample_rate, i, audio_enc->sample_rate, oc, st);

​

-        MATCH_PER_STREAM_OPT(apad, str, ost->apad, oc, st);

-        ost->apad = av_strdup(ost->apad);

+        MATCH_PER_STREAM_OPT(apad, str, apad, oc, st);

+        if (apad) {

+            ost->apad = av_strdup(apad);

+            if (!ost->apad)

+                return AVERROR(ENOMEM);

+        }

​

 #if FFMPEG_OPT_MAP_CHANNEL

         /* check for channel mapping for this audio stream */

--

2.41.0

​

​