From 741cfd18b591b3796b73b1a9bc91a57d0469243b Mon Sep 17 00:00:00 2001 From: Matthew Waters Date: Fri, 6 May 2022 14:00:38 +1000 Subject: [PATCH] ccconverter: drop data when overflow on extracting cea608 from cc_data 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: --- .../ext/closedcaption/gstccconverter.c | 49 ++++++++---- .../tests/check/elements/ccconverter.c | 88 ++++++++++++++++++++++ 2 files changed, 121 insertions(+), 16 deletions(-) diff --git a/subprojects/gst-plugins-bad/ext/closedcaption/gstccconverter.c b/subprojects/gst-plugins-bad/ext/closedcaption/gstccconverter.c index b22baa0..1774364 100644 --- a/subprojects/gst-plugins-bad/ext/closedcaption/gstccconverter.c +++ b/subprojects/gst-plugins-bad/ext/closedcaption/gstccconverter.c @@ -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 > diff --git a/subprojects/gst-plugins-bad/tests/check/elements/ccconverter.c b/subprojects/gst-plugins-bad/tests/check/elements/ccconverter.c index 4d4d38e..a925087 100644 --- a/subprojects/gst-plugins-bad/tests/check/elements/ccconverter.c +++ b/subprojects/gst-plugins-bad/tests/check/elements/ccconverter.c @@ -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; } -- 2.7.4