[vlc-commits] [Git][videolan/vlc][3.0.x] cvdsub: do not read header if there is not enough data

[Steve Lhomme (@robUx4)]

Steve Lhomme pushed to branch 3.0.x at VideoLAN / VLC


Commits:
55d6515a by Steve Lhomme at 2026-08-21T11:40:03+00:00
cvdsub: do not read header if there is not enough data

Each block seems to need a 1 octet between valid data (SPU_HEADER_LEN).
We are expecting a header but it's not there, wait for the next packet.

Fixes #30037

(cherry picked from commit 1c21459f7ad8a43e3dc2d3e3596a8ffb361e7dab) (edited)
edited:
- VLC 3 doesn't have VLC_EINVAL
Signed-off-by: Steve Lhomme <robux4 at ycbcr.xyz>

- - - - -


1 changed file:

- modules/codec/cvdsub.c


Changes:

=====================================
modules/codec/cvdsub.c
=====================================
@@ -64,7 +64,7 @@ static int Decode( decoder_t *, block_t * );
 static block_t *Packetize  ( decoder_t *, block_t ** );
 static block_t *Reassemble ( decoder_t *, block_t * );
 static void ParseMetaInfo  ( decoder_t *, block_t * );
-static void ParseHeader    ( decoder_t *, block_t * );
+static int  ParseHeader    ( decoder_t *, block_t * );
 static subpicture_t *DecodePacket( decoder_t *, block_t * );
 static void RenderImage( decoder_t *, block_t *, subpicture_region_t * );
 
@@ -250,7 +250,15 @@ static block_t *Reassemble( decoder_t *p_dec, block_t *p_block )
     p_block->i_buffer -= SPU_HEADER_LEN;
 
     /* First packet in the subtitle block */
-    if( p_sys->i_state == SUBTITLE_BLOCK_EMPTY ) ParseHeader( p_dec, p_block );
+    if( p_sys->i_state == SUBTITLE_BLOCK_EMPTY )
+    {
+        if( ParseHeader( p_dec, p_block ) != VLC_SUCCESS )
+        {
+            msg_Warn( p_dec, "Missing header data");
+            block_Release( p_block );
+            return NULL;
+        }
+    }
 
     block_ChainAppend( &p_sys->p_spu, p_block );
     p_sys->p_spu = block_ChainGather( p_sys->p_spu );
@@ -265,7 +273,7 @@ static block_t *Reassemble( decoder_t *p_dec, block_t *p_block )
                       p_spu->i_buffer, p_sys->i_spu_size );
         }
 
-        msg_Dbg( p_dec, "subtitle packet complete, size=%zuu", p_spu->i_buffer);
+        msg_Dbg( p_dec, "subtitle packet complete, size=%zu", p_spu->i_buffer);
 
         ParseMetaInfo( p_dec, p_spu );
 
@@ -308,10 +316,12 @@ static block_t *Reassemble( decoder_t *p_dec, block_t *p_block )
   this, so it may be untested.
 */
 
-static void ParseHeader( decoder_t *p_dec, block_t *p_block )
+static int ParseHeader( decoder_t *p_dec, block_t *p_block )
 {
     decoder_sys_t *p_sys = p_dec->p_sys;
     uint8_t *p = p_block->p_buffer;
+    if (p_block->i_buffer < 4)
+        return VLC_EGENERIC; // not enough data
 
     p_sys->i_spu_size = (p[0] << 8) + p[1] + 4; p += 2;
 
@@ -328,6 +338,7 @@ static void ParseHeader( decoder_t *p_dec, block_t *p_block )
     msg_Dbg( p_dec, "total size: %zu  image size: %zu",
              p_sys->i_spu_size, p_sys->i_image_length );
 #endif
+    return VLC_SUCCESS;
 }
 
 /*



View it on GitLab: https://code.videolan.org/videolan/vlc/-/commit/55d6515a89b2493a4e46eb601621e4679efbe609

-- 
View it on GitLab: https://code.videolan.org/videolan/vlc/-/commit/55d6515a89b2493a4e46eb601621e4679efbe609
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