[vlc-commits] demux: xiph: rewrite to split cases handling
Francois Cartegnie
git at videolan.org
Wed Aug 14 18:13:24 CEST 2019
vlc | branch: master | Francois Cartegnie <fcvlcdev at free.fr> | Fri Jul 26 20:12:41 2019 +0200| [93f04f42e92df8af1697a3c990c88d62eb7f528d] | committer: Hugo Beauzée-Luyssen
demux: xiph: rewrite to split cases handling
CVE-2019-14437, CVE-2019-14438
Signed-off-by: Hugo Beauzée-Luyssen <hugo at beauzee.fr>
> http://git.videolan.org/gitweb.cgi/vlc.git/?a=commit;h=93f04f42e92df8af1697a3c990c88d62eb7f528d
---
modules/demux/xiph.h | 153 ++++++++++++++++++++++++++++++++-------------------
modules/mux/ogg.c | 4 +-
2 files changed, 98 insertions(+), 59 deletions(-)
diff --git a/modules/demux/xiph.h b/modules/demux/xiph.h
index 3723814a57..34917ab637 100644
--- a/modules/demux/xiph.h
+++ b/modules/demux/xiph.h
@@ -21,92 +21,130 @@
*****************************************************************************/
#include <assert.h>
+#include <limits.h>
#define XIPH_MAX_HEADER_COUNT (256)
/* Temp ffmpeg vorbis format */
-static inline bool xiph_IsOldFormat( const void *extra, unsigned int i_extra )
+static inline bool xiph_IsLavcFormat(const void *extra, unsigned i_extra)
{
- if ( i_extra >= 6 && GetWBE( extra ) == 30 )
- return true;
- else
- return false;
+ return (i_extra >= 6 && GetWBE(extra) == 30);
}
-static inline unsigned int xiph_CountHeaders( const void *extra, unsigned int i_extra )
+static inline unsigned xiph_CountLavcHeaders(const void *p_extra, unsigned i_extra)
{
- const uint8_t *p_extra = (uint8_t*) extra;
- if ( !i_extra ) return 0;
- if ( xiph_IsOldFormat( extra, i_extra ) )
+ const uint8_t *p = (const uint8_t*) p_extra;
+ const uint8_t *p_end = &p[i_extra];
+ /* Check headers count */
+ for (int i=0; i<3; i++)
{
- /* Check headers count */
- unsigned int overall_len = 6;
- for ( int i=0; i<3; i++ )
- {
- uint16_t i_size = GetWBE( extra );
- p_extra += 2 + i_size;
- if ( i_extra < i_size || overall_len > i_extra - i_size )
- return 0;
- overall_len += i_size;
- }
- return 3;
+ if(p_end - p < 2)
+ return 0;
+ uint16_t i_size = GetWBE(p);
+ if(&p[2U + i_size] > p_end)
+ return 0;
+ p += 2 + i_size;
}
+ return 3;
+}
+
+static inline unsigned xiph_CountHeaders(const void *p_extra, unsigned i_extra)
+{
+ const uint8_t *p = (const uint8_t*) p_extra;
+ if (!i_extra)
+ return 0;
+ /* First byte is headers count */
+ if(1U + *p > i_extra)
+ return 0;
+ return *p + 1;
+}
+
+static inline unsigned xiph_CountUnknownHeaders(const void *p_extra, unsigned i_extra)
+{
+ if (xiph_IsLavcFormat(p_extra, i_extra))
+ return xiph_CountLavcHeaders(p_extra, i_extra);
else
+ return xiph_CountHeaders(p_extra, i_extra);
+}
+
+static inline int xiph_SplitLavcHeaders(unsigned packet_size[],
+ const void *packet[], unsigned *packet_count,
+ unsigned i_extra, const void *p_extra)
+{
+ const uint8_t *current = (const uint8_t *)p_extra;
+ const uint8_t *end = ¤t[i_extra];
+ if (i_extra < 2)
+ return VLC_EGENERIC;
+ /* Parse the packet count and their sizes */
+ const unsigned count = xiph_CountLavcHeaders(current, i_extra);
+ if(count == 0)
+ return VLC_EGENERIC;
+ if (packet_count)
+ *packet_count = count;
+ /* count is trusted here (xiph_CountHeaders) */
+ for (unsigned i=0; i < count; i++)
{
- return *p_extra + 1;
+ /* each payload is prefixed by word size */
+ packet_size[i] = GetWBE(current);
+ if(¤t[2U + packet_size[i]] > end)
+ return VLC_EGENERIC;
+ packet[i] = current + 2;
+ current += packet_size[i] + 2;
}
+ return VLC_SUCCESS;
}
static inline int xiph_SplitHeaders(unsigned packet_size[],
const void *packet[], unsigned *packet_count,
- unsigned extra_size, const void *extra)
+ unsigned i_extra, const void *p_extra)
{
- const uint8_t *current = (const uint8_t *)extra;
- const uint8_t *end = ¤t[extra_size];
- if (extra_size < 1)
+ const uint8_t *current = (const uint8_t *)p_extra;
+ const uint8_t *end = ¤t[i_extra];
+ if (i_extra < 1)
return VLC_EGENERIC;
/* Parse the packet count and their sizes */
- const unsigned count = xiph_CountHeaders( current++, extra_size );
+ const unsigned count = xiph_CountHeaders(current, i_extra);
+ if(count == 0)
+ return VLC_EGENERIC;
+
if (packet_count)
*packet_count = count;
- if ( xiph_IsOldFormat( extra, extra_size ) )
+ /* - 1 byte (N-1) packets
+ * - N-1 variable length payload sizes
+ * - N-1 payloads
+ * - Nth packet (remaining) */
+
+ /* skip count byte header */
+ ++current;
+ /* read sizes for N-1 packets */
+ unsigned total_payload_minus_last = 0;
+ for (unsigned i = 0; i < count - 1; i++)
{
- uint8_t *p_extra = (uint8_t*) extra;
- unsigned int overall_len = count << 1;
- for ( unsigned int i=0; i < count; i++ ) {
- packet_size[i] = GetWBE( p_extra );
- packet[i] = p_extra + 2;
- p_extra += packet_size[i] + 2;
- if (overall_len > extra_size - packet_size[i])
+ packet_size[i] = 0;
+ for (;;) {
+ if (current >= end)
return VLC_EGENERIC;
- overall_len += packet_size[i];
+ packet_size[i] += *current;
+ if (*current++ != 255)
+ break;
}
+ if(UINT_MAX - total_payload_minus_last < packet_size[i])
+ return VLC_EGENERIC;
+ total_payload_minus_last += packet_size[i];
}
- else
+ if(current + total_payload_minus_last > end)
+ return VLC_EGENERIC;
+ /* set pointers for N-1 packets */
+ for (unsigned i = 0; i < count - 1; i++)
{
- int size = 0;
- for (unsigned i = 0; i < count - 1; i++) {
- packet_size[i] = 0;
- for (;;) {
- if (current >= end)
- return VLC_EGENERIC;
- packet_size[i] += *current;
- if (*current++ != 255)
- break;
- }
- size += packet_size[i];
- }
- if (end - current < size)
- return VLC_EGENERIC;
- packet_size[count - 1] = end - current - size;
-
- for (unsigned i = 0; i < count; i++)
- if (packet_size[i] > 0) {
- packet[i] = (void *) current;
- current += packet_size[i];
- }
+ packet[i] = current;
+ current += packet_size[i];
}
+ /* Last packet is remaining size */
+ packet_size[count - 1] = end - current;
+ packet[count - 1] = current;
+
return VLC_SUCCESS;
}
@@ -192,4 +230,3 @@ static inline int xiph_AppendHeaders(int *extra_size, void **extra,
return VLC_EGENERIC;
return VLC_SUCCESS;
}
-
diff --git a/modules/mux/ogg.c b/modules/mux/ogg.c
index c41b940434..41e2507a1f 100644
--- a/modules/mux/ogg.c
+++ b/modules/mux/ogg.c
@@ -838,7 +838,9 @@ static void OggGetSkeletonFisbone( uint8_t **pp_buffer, long *pi_size,
/* preroll */
if ( p_input->p_fmt->p_extra )
- SetDWLE( &(*pp_buffer)[44], xiph_CountHeaders( p_input->p_fmt->p_extra, p_input->p_fmt->i_extra ) );
+ SetDWLE( &(*pp_buffer)[44],
+ xiph_CountUnknownHeaders( p_input->p_fmt->p_extra,
+ p_input->p_fmt->i_extra ) );
if ( headers.i_size > 0 )
{
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