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qtdemux: Guard against 64-bit overflow

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For large-file atoms, guard against overflow in the size field,
which could make us jump backward in the file and cause
infinite loops.
This commit is contained in:
Jan Schmidt 2015-04-03 02:08:50 +11:00
parent 3d59b5f814
commit ffa5fce094
1 changed files with 12 additions and 3 deletions
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15
gst/isomp4/qtdemux.c
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@ -2369,7 +2369,7 @@ extract_initial_length_and_fourcc (const guint8 * data, guint size,
GST_DEBUG ("atom type %" GST_FOURCC_FORMAT, GST_FOURCC_ARGS (fourcc));
if (length == 0) {
length = G_MAXUINT32;
length = G_MAXUINT64;
} else if (length == 1 && size >= 16) {
/* this means we have an extended size, which is the 64 bit value of
* the next 8 bytes */
@ -3240,6 +3240,15 @@ broken_file:
}
}
static guint64
add_offset (guint64 offset, guint64 advance)
{
/* Avoid 64-bit overflow by clamping */
if (offset > G_MAXUINT64 - advance)
return G_MAXUINT64;
return offset + advance;
}
static GstFlowReturn
gst_qtdemux_loop_state_header (GstQTDemux * qtdemux)
{
@ -3293,7 +3302,7 @@ gst_qtdemux_loop_state_header (GstQTDemux * qtdemux)
GST_LOG_OBJECT (qtdemux,
"skipping atom '%" GST_FOURCC_FORMAT "' at %" G_GUINT64_FORMAT,
GST_FOURCC_ARGS (fourcc), cur_offset);
qtdemux->offset += length;
qtdemux->offset = add_offset (qtdemux->offset, length);
break;
}
case FOURCC_moov:
@ -3302,7 +3311,7 @@ gst_qtdemux_loop_state_header (GstQTDemux * qtdemux)
if (qtdemux->got_moov) {
GST_DEBUG_OBJECT (qtdemux, "Skipping moov atom as we have one already");
qtdemux->offset += length;
qtdemux->offset = add_offset (qtdemux->offset, length);
goto beach;
}