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ccconverter: drop data when overflow on extracting cea608 from cc_data

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If the buffer overflows, then drop rather than causing a failure and
fropping the output buffer indefinitely.  This may have caused downstream to
be waiting for data the will never arrive.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/3211>
This commit is contained in:
Matthew Waters 2022-05-06 14:00:38 +10:00 committed by GStreamer Marge Bot
parent 542060fea7
commit 741cfd18b5
2 changed files with 121 additions and 16 deletions
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49
subprojects/gst-plugins-bad/ext/closedcaption/gstccconverter.c
View file

@ -647,6 +647,9 @@ compact_cc_data (guint8 * cc_data, guint cc_data_len)
return out_len;
}
#define CC_DATA_EXTRACT_TOO_MANY_FIELD1 -2
#define CC_DATA_EXTRACT_TOO_MANY_FIELD2 -3
static gint
cc_data_extract_cea608 (guint8 * cc_data, guint cc_data_len,
guint8 * cea608_field1, guint * cea608_field1_len,
@ -687,7 +690,7 @@ cc_data_extract_cea608 (guint8 * cc_data, guint cc_data_len,
if (*cea608_field1_len + 2 > field_1_len) {
GST_WARNING ("Too many cea608 input bytes %u for field 1",
*cea608_field1_len + 2);
return -1;
return CC_DATA_EXTRACT_TOO_MANY_FIELD1;
}
if (byte1 != 0x80 || byte2 != 0x80) {
@ -703,7 +706,7 @@ cc_data_extract_cea608 (guint8 * cc_data, guint cc_data_len,
if (*cea608_field2_len + 2 > field_2_len) {
GST_WARNING ("Too many cea608 input bytes %u for field 2",
*cea608_field2_len + 2);
return -1;
return CC_DATA_EXTRACT_TOO_MANY_FIELD2;
}
if (byte1 != 0x80 || byte2 != 0x80) {
cea608_field2[(*cea608_field2_len)++] = byte1;
@ -1510,15 +1513,6 @@ cc_data_to_cea608_ccp (GstCCConverter * self, guint8 * cc_data,
guint new_cea608_1_len = 0, new_cea608_2_len = 0;
guint8 *new_cea608_1 = cea608_1, *new_cea608_2 = cea608_2;
if (cea608_1_len) {
new_cea608_1_len = cea608_1_in_size - *cea608_1_len;
new_cea608_1 = &cea608_1[*cea608_1_len];
}
if (cea608_2_len) {
new_cea608_2_len = cea608_2_in_size - *cea608_2_len;
new_cea608_2 = &cea608_2[*cea608_2_len];
}
cc_data_len = compact_cc_data (cc_data, cc_data_len);
if (cc_data_len / 3 > in_fps_entry->max_cc_count) {
@ -1527,11 +1521,34 @@ cc_data_to_cea608_ccp (GstCCConverter * self, guint8 * cc_data,
cc_data_len = 3 * in_fps_entry->max_cc_count;
}
ccp_offset = cc_data_extract_cea608 (cc_data, cc_data_len, new_cea608_1,
&new_cea608_1_len, new_cea608_2, &new_cea608_2_len);
if (ccp_offset < 0) {
GST_WARNING_OBJECT (self, "Failed to extract cea608 from cc_data");
goto fail;
while (TRUE) {
if (cea608_1_len) {
new_cea608_1_len = cea608_1_in_size - *cea608_1_len;
new_cea608_1 = &cea608_1[*cea608_1_len];
}
if (cea608_2_len) {
new_cea608_2_len = cea608_2_in_size - *cea608_2_len;
new_cea608_2 = &cea608_2[*cea608_2_len];
}
ccp_offset = cc_data_extract_cea608 (cc_data, cc_data_len, new_cea608_1,
&new_cea608_1_len, new_cea608_2, &new_cea608_2_len);
if (ccp_offset == CC_DATA_EXTRACT_TOO_MANY_FIELD1 && cea608_1_len) {
GST_WARNING_OBJECT (self, "cea608 field 1 overflow, dropping all "
"previously stored field 1 data and trying again");
*cea608_1_len = 0;
} else if (ccp_offset == CC_DATA_EXTRACT_TOO_MANY_FIELD2 && cea608_2_len) {
GST_WARNING_OBJECT (self, "cea608 field 2 overflow, dropping all "
"previously stored field 2 data and trying again");
*cea608_2_len = 0;
} else if (ccp_offset < 0) {
GST_WARNING_OBJECT (self, "Failed to extract cea608 from cc_data");
goto fail;
} else {
/* success */
break;
}
}
if ((new_cea608_1_len + new_cea608_2_len) / 2 >

88
subprojects/gst-plugins-bad/tests/check/elements/ccconverter.c
View file

@ -1073,6 +1073,93 @@ GST_START_TEST (convert_cea708_cc_data_cea708_cdp_double_input_data)
GST_END_TEST;
static guint8
calculate_cdp_checksum (guint8 * cdp, gsize len)
{
guint8 checksum = 0;
gsize i;
for (i = 0; i < len; i++) {
checksum += cdp[i];
}
checksum &= 0xff;
return 256 - checksum;
}
GST_START_TEST (convert_cea708_cc_data_cea708_cdp_field1_overflow)
{
/* caps say 60fps, but every buffer is cea608 field 1. Ensure data is taken
* alternatatively from each field even if there is too much input data.
* Also ensure that overflow does something sane, like dropping previous data */
#define N_INPUTS 100
guint8 in_data[N_INPUTS * 3];
guint in_len[N_INPUTS];
guint8 *in[N_INPUTS];
guint i;
#define N_OUTPUTS 100
guint8 out_data[N_OUTPUTS * 43];
guint out_len[N_OUTPUTS];
guint8 *out[N_OUTPUTS];
const guint8 out_template[] =
{ 0x96, 0x69, 0x2b, 0x8f, 0x43, 0x00, 0x01, 0x72, 0xea, 0xf9, 0x80, 0x80,
0xfa, 0x00, 0x00, 0xfa, 0x00, 0x00, 0xfa, 0x00, 0x00, 0xfa, 0x00, 0x00,
0xfa, 0x00, 0x00, 0xfa, 0x00, 0x00, 0xfa, 0x00, 0x00, 0xfa, 0x00, 0x00,
0xfa, 0x00, 0x00, 0x74, 0x00, 0x01, 0x6f
};
G_STATIC_ASSERT (sizeof (out_template) == 43);
/* generate input data */
for (i = 0; i < N_INPUTS; i++) {
in_len[i] = 3;
in_data[i * 3 + 0] = 0xfc;
in_data[i * 3 + 1] = 0x81 + i * 2;
in_data[i * 3 + 2] = 0x81 + i * 2 + 1;
in[i] = &in_data[i * 3];
}
for (i = 0; i < N_OUTPUTS; i++) {
out_len[i] = 43;
memcpy (&out_data[i * 43], out_template, sizeof (out_template));
/* write correct counters */
out_data[i * 43 + 6] = i;
out_data[i * 43 + 41] = i;
/* write the correct cea608 data */
if (i % 2 == 0) {
gsize in_data_offset;
/* take frames sequentially from the input */
gsize in_idx = i / 2;
/* take the first 16 input frames, then skip the next 16 frames and take
* the next 16 frames etc.
* 32 is the byte size of the internal cea608 field buffers that we are
* overflowing but every second buffer will have cea608 field 1 in it.
* 16 frames is 32 bytes stored and is enough to cause overflow */
in_idx = (in_idx / 16) * 32 + in_idx % 16;
in_data_offset = in_idx * 3;
out_data[i * 43 + 9] = in_data[in_data_offset + 0];
out_data[i * 43 + 10] = in_data[in_data_offset + 1];
out_data[i * 43 + 11] = in_data[in_data_offset + 2];
} else {
out_data[i * 43 + 9] = 0xf9;
out_data[i * 43 + 10] = 0x80;
out_data[i * 43 + 11] = 0x80;
}
out_data[i * 43 + 42] = calculate_cdp_checksum (&out_data[i * 43], 42);
out[i] = &out_data[i * 43];
}
check_conversion_multiple (G_N_ELEMENTS (in_len), (const guint8 **) in,
in_len, G_N_ELEMENTS (out_len), (const guint8 **) out, out_len,
"closedcaption/x-cea-708,format=(string)cc_data,framerate=(fraction)60/1",
"closedcaption/x-cea-708,format=(string)cdp,framerate=(fraction)60/1",
NULL, NULL, FLAG_SEND_EOS);
}
GST_END_TEST;
static Suite *
ccextractor_suite (void)
{
@ -1110,6 +1197,7 @@ ccextractor_suite (void)
tcase_add_test (tc, convert_cea608_s334_1a_cea708_cdp_double_framerate);
tcase_add_test (tc, convert_cea708_cdp_cea708_cc_data_double_input_data);
tcase_add_test (tc, convert_cea708_cc_data_cea708_cdp_double_input_data);
tcase_add_test (tc, convert_cea708_cc_data_cea708_cdp_field1_overflow);
return s;
}