[FFmpeg-devel] [PATCH 1/4] avcodec/ac3_parser: use a padded buffer in av_ac3_parse_header()

[James Almer <jamrial@gmail.com>]

The GetBitContext API requires the buffer to be padded, and the documentation for
av_ac3_parse_header() does not specify it, so use a temporary local buffer.

Signed-off-by: James Almer <jamrial@gmail.com>
---
 libavcodec/ac3_parser.c | 16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/libavcodec/ac3_parser.c b/libavcodec/ac3_parser.c
index 69989690dd..9065d700e2 100644
--- a/libavcodec/ac3_parser.c
+++ b/libavcodec/ac3_parser.c
@@ -202,14 +202,24 @@ int av_ac3_parse_header(const uint8_t *buf, size_t size,
 {
     GetBitContext gb;
     AC3HeaderInfo hdr;
+    uint8_t *tmp = av_malloc(size + AV_INPUT_BUFFER_PADDING_SIZE);
     int err;
 
-    err = init_get_bits8(&gb, buf, size);
-    if (err < 0)
+    if (!tmp)
+        return AVERROR(ENOMEM);
+
+    memcpy(tmp, buf, size);
+    memset(tmp + size, 0, AV_INPUT_BUFFER_PADDING_SIZE);
+    err = init_get_bits8(&gb, tmp, size);
+    if (err < 0) {
+        av_free(tmp);
         return AVERROR_INVALIDDATA;
+    }
     err = ff_ac3_parse_header(&gb, &hdr);
-    if (err < 0)
+    if (err < 0) {
+        av_free(tmp);
         return AVERROR_INVALIDDATA;
+    }
 
     *bitstream_id = hdr.bitstream_id;
     *frame_size   = hdr.frame_size;
-- 
2.49.0

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