[FFmpeg-cvslog] avcodec/hevc/hevcdec: move the slice header buffer overread check up in the function

[James Almer]

ffmpeg | branch: master | James Almer <jamrial at gmail.com> | Fri May  2 16:28:24 2025 -0300| [0af1d69959696aa4baab7feef361e57d62f2e3f4] | committer: James Almer

avcodec/hevc/hevcdec: move the slice header buffer overread check up in the function

Abort as soon as we're done reading the slice header instead of running extra checks
that assume slice data may follow.

Signed-off-by: James Almer <jamrial at gmail.com>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=0af1d69959696aa4baab7feef361e57d62f2e3f4
---

 libavcodec/hevc/hevcdec.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/libavcodec/hevc/hevcdec.c b/libavcodec/hevc/hevcdec.c
index df186d6194..a7a91769fe 100644
--- a/libavcodec/hevc/hevcdec.c
+++ b/libavcodec/hevc/hevcdec.c
@@ -1160,6 +1160,12 @@ static int hls_slice_header(SliceHeader *sh, const HEVCContext *s, GetBitContext
     }
     sh->data_offset = align_get_bits(gb) - gb->buffer;
 
+    if (get_bits_left(gb) < 0) {
+        av_log(s->avctx, AV_LOG_ERROR,
+               "Overread slice header by %d bits\n", -get_bits_left(gb));
+        return AVERROR_INVALIDDATA;
+    }
+
     // Inferred parameters
     sh->slice_qp = 26U + pps->pic_init_qp_minus26 + sh->slice_qp_delta;
     if (sh->slice_qp > 51 ||
@@ -1180,12 +1186,6 @@ static int hls_slice_header(SliceHeader *sh, const HEVCContext *s, GetBitContext
         return AVERROR_INVALIDDATA;
     }
 
-    if (get_bits_left(gb) < 0) {
-        av_log(s->avctx, AV_LOG_ERROR,
-               "Overread slice header by %d bits\n", -get_bits_left(gb));
-        return AVERROR_INVALIDDATA;
-    }
-
     return 0;
 }