[FFmpeg-devel] [PATCH 1/3] avcodec/alsdec: Limit maximum channels to 64

[Michael Niedermayer]

There seems to be no limit in the specification and upto 64k could be stored
64 is chooses as limit as thats also used for AAC and is what a int64 mask
can handle

An alternative to this patch would be a max_channels variable

Fixes: OOM
Fixes: 16200/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_ALS_fuzzer-5764788793114624

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
---
 libavcodec/alsdec.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/libavcodec/alsdec.c b/libavcodec/alsdec.c
index 26c496c769..425cf73be9 100644
--- a/libavcodec/alsdec.c
+++ b/libavcodec/alsdec.c
@@ -43,6 +43,8 @@
 
 #include <stdint.h>
 
+#define MAX_CHANNELS 64
+
 /** Rice parameters and corresponding index offsets for decoding the
  *  indices of scaled PARCOR values. The table chosen is set globally
  *  by the encoder and stored in ALSSpecificConfig.
@@ -348,6 +350,11 @@ static av_cold int read_specific_config(ALSDecContext *ctx)
     if (als_id != MKBETAG('A','L','S','\0'))
         return AVERROR_INVALIDDATA;
 
+    if (avctx->channels > MAX_CHANNELS) {
+        avpriv_request_sample(avctx, "Huge number of channels\n");
+        return AVERROR_PATCHWELCOME;
+    }
+
     ctx->cur_frame_length = sconf->frame_length;
 
     // read channel config
-- 
2.22.1