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demux_mkv: fix EBML parsing checks 

Reading IDs must be checked too. This was basically forgotten in commit
f3a978cd. Also set the *length parameter for ebml_parse_length() in some
error cases, which _really_ should happen.

Fixes #1461.
This commit is contained in:
wm4 2015-01-12 14:31:16 +01:00 committed by Diogo Franco (Kovensky)
parent 1a3a52ea25
commit 42f82c5ccf
1 changed files with 15 additions and 16 deletions
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31
demux/ebml.c
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@ -262,25 +262,28 @@ int ebml_resync_cluster(struct mp_log *log, stream_t *s)
struct generic;
#define generic_struct struct generic
static uint32_t ebml_parse_id(uint8_t *data, int *length)
static uint32_t ebml_parse_id(uint8_t *data, size_t data_len, int *length)
{
*length = -1;
uint8_t *end = data + data_len;
if (data == end)
return EBML_ID_INVALID;
int len = 1;
uint32_t id = *data++;
for (int len_mask = 0x80; !(id & len_mask); len_mask >>= 1) {
len++;
if (len > 4) {
*length = -1;
if (len > 4)
return EBML_ID_INVALID;
}
}
*length = len;
while (--len)
while (--len && data < end)
id = (id << 8) | *data++;
return id;
}
static uint64_t ebml_parse_length(uint8_t *data, size_t data_len, int *length)
{
*length = -1;
uint8_t *end = data + data_len;
if (data == end)
return -1;
@ -289,10 +292,8 @@ static uint64_t ebml_parse_length(uint8_t *data, size_t data_len, int *length)
int len_mask;
for (len_mask = 0x80; !(r & len_mask); len_mask >>= 1) {
len++;
if (len > 8) {
*length = -1;
if (len > 8)
return -1;
}
}
r &= len_mask - 1;
@ -306,12 +307,10 @@ static uint64_t ebml_parse_length(uint8_t *data, size_t data_len, int *length)
num_allones++;
r = (r << 8) | *data++;
}
if (num_allones == len) {
// According to Matroska specs this means "unknown length"
// Could be supported if there are any actual files using it
*length = -1;
// According to Matroska specs this means "unknown length"
// Could be supported if there are any actual files using it
if (num_allones == len)
return -1;
}
*length = len;
return r;
}
@ -363,7 +362,7 @@ static void ebml_parse_element(struct ebml_parse_ctx *ctx, void *target,
while (p < end) {
uint8_t *startp = p;
int len;
uint32_t id = ebml_parse_id(p, &len);
uint32_t id = ebml_parse_id(p, end - p, &len);
if (len > end - p)
goto past_end_error;
if (len < 0) {
@ -458,7 +457,7 @@ static void ebml_parse_element(struct ebml_parse_ctx *ctx, void *target,
while (data < end) {
int len;
uint32_t id = ebml_parse_id(data, &len);
uint32_t id = ebml_parse_id(data, end - data, &len);
if (len < 0 || len > end - data) {
MP_DBG(ctx, "Error parsing subelement\n");
break;
@ -588,7 +587,7 @@ static void ebml_parse_element(struct ebml_parse_ctx *ctx, void *target,
case EBML_TYPE_EBML_ID:;
uint32_t *idptr;
GETPTR(idptr, uint32_t);
*idptr = ebml_parse_id(data, &len);
*idptr = ebml_parse_id(data, end - data, &len);
if (len != length) {
MP_DBG(ctx, "ebml_id broken value\n");
goto error;