[FFmpeg-devel] [PATCH] avcodec/eatgq: prevent out of bounds memory access and endless loop

[Peter Ross <pross@xvid.org>]

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---
 libavcodec/eatgq.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/libavcodec/eatgq.c b/libavcodec/eatgq.c
index 89e9f20880..fdda8286ef 100644
--- a/libavcodec/eatgq.c
+++ b/libavcodec/eatgq.c
@@ -56,7 +56,7 @@ static av_cold int tgq_decode_init(AVCodecContext *avctx)
     return 0;
 }
 
-static void tgq_decode_block(TgqContext *s, int16_t block[64], GetBitContext *gb)
+static int tgq_decode_block(TgqContext *s, int16_t block[64], GetBitContext *gb)
 {
     const uint8_t *scantable = ff_zigzag_direct;
     int i, j, value;
@@ -73,7 +73,9 @@ static void tgq_decode_block(TgqContext *s, int16_t block[64], GetBitContext *gb
         case 1:
             skip_bits(gb, 2);
             value = get_bits(gb, 6);
-            for (j = 0; j < value; j++)
+            if (!value)
+                return AVERROR_INVALIDDATA;
+            for (j = 0; j < value && i < 64; j++)
                 block[scantable[i++]] = 0;
             break;
         case 6:
@@ -100,6 +102,7 @@ static void tgq_decode_block(TgqContext *s, int16_t block[64], GetBitContext *gb
         }
     }
     block[0] += 128 << 4;
+    return 0;
 }
 
 static void tgq_idct_put_mb(TgqContext *s, int16_t (*block)[64], AVFrame *frame,
@@ -161,7 +164,8 @@ static int tgq_decode_mb(TgqContext *s, GetByteContext *gbyte,
             return ret;
 
         for (i = 0; i < 6; i++)
-            tgq_decode_block(s, s->block[i], &gb);
+            if ((ret = tgq_decode_block(s, s->block[i], &gb)) < 0)
+                return ret;
         tgq_idct_put_mb(s, s->block, frame, mb_x, mb_y);
         bytestream2_skip(gbyte, mode);
     } else {
-- 
2.35.1

-- Peter
(A907 E02F A6E5 0CD2 34CD 20D2 6760 79C5 AC40 DD6B)

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