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mpegtssection: Add more section size checks

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The smallest section ever needs to be at least 3 bytes (i.e. just the short
header).
Non-short headers need to be at least 11 bytes long (3 for the minimum header,
5 for the non-short header, and 4 for the CRC).

https://bugzilla.gnome.org/show_bug.cgi?id=775048
This commit is contained in:
Edward Hervey 2016-11-26 10:44:43 +01:00 committed by Edward Hervey
parent 7b12593cce
commit d58f668ece
1 changed files with 22 additions and 1 deletions
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23
gst-libs/gst/mpegts/gstmpegtssection.c
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@ -1179,13 +1179,20 @@ gst_mpegts_section_new (guint16 pid, guint8 * data, gsize data_size)
GstMpegtsSection *res = NULL; GstMpegtsSection *res = NULL;
guint8 tmp; guint8 tmp;
guint8 table_id; guint8 table_id;
guint16 section_length; guint16 section_length = 0;
/* The smallest section ever is 3 bytes */
if (G_UNLIKELY (data_size < 3))
goto short_packet;
/* Check for length */ /* Check for length */
section_length = GST_READ_UINT16_BE (data + 1) & 0x0FFF; section_length = GST_READ_UINT16_BE (data + 1) & 0x0FFF;
if (G_UNLIKELY (data_size < section_length + 3)) if (G_UNLIKELY (data_size < section_length + 3))
goto short_packet; goto short_packet;
GST_LOG ("data_size:%" G_GSIZE_FORMAT " section_length:%u",
data_size, section_length);
/* Table id is in first byte */ /* Table id is in first byte */
table_id = *data; table_id = *data;
@ -1200,6 +1207,13 @@ gst_mpegts_section_new (guint16 pid, guint8 * data, gsize data_size)
/* section_length (already parsed) : 12 bit */ /* section_length (already parsed) : 12 bit */
res->section_length = section_length + 3; res->section_length = section_length + 3;
if (!res->short_section) { if (!res->short_section) {
/* A long packet needs to be at least 11 bytes long
* _ 3 for the bytes above
* _ 5 for the bytes below
* _ 4 for the CRC */
if (G_UNLIKELY (data_size < 11))
goto bad_long_packet;
/* CRC is after section_length (-4 for the size of the CRC) */ /* CRC is after section_length (-4 for the size of the CRC) */
res->crc = GST_READ_UINT32_BE (res->data + res->section_length - 4); res->crc = GST_READ_UINT32_BE (res->data + res->section_length - 4);
/* Skip to after section_length */ /* Skip to after section_length */
@ -1229,6 +1243,13 @@ short_packet:
g_free (data); g_free (data);
return NULL; return NULL;
} }
bad_long_packet:
{
GST_WARNING ("PID 0x%04x long section is too short (%" G_GSIZE_FORMAT
" bytes, need at least 11)", pid, data_size);
gst_mpegts_section_unref (res);
return NULL;
}
} }
/** /**