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Fix some fuzz finds in grabbag picture code

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- Check for chunk length overflow in PNG reading code
- Check for empty file
- Check for empty URL
This commit is contained in:
Martijn van Beurden 2023-02-21 11:17:01 +01:00
parent 21ffc935f0
commit 1a8279b7d1
1 changed files with 12 additions and 5 deletions

17
src/share/grabbag/picture.c

@ -142,7 +142,10 @@ static FLAC__bool local__extract_resolution_color_info_(FLAC__StreamMetadata_Pic
len -= 8;
while(len > 12) { /* every PNG chunk must be at least 12 bytes long */
const FLAC__uint32 clen = (FLAC__uint32)data[0] << 24 | (FLAC__uint32)data[1] << 16 | (FLAC__uint32)data[2] << 8 | (FLAC__uint32)data[3];
if(0 == memcmp(data+4, "IHDR", 4) && clen == 13) {
/* First check whether clen makes sense or causes overflow in this bit of code */
if(clen + 12 <= clen || clen + 12 > len)
return false;
else if(0 == memcmp(data+4, "IHDR", 4) && clen == 13) {
uint32_t color_type = data[17];
picture->width = (FLAC__uint32)data[8] << 24 | (FLAC__uint32)data[9] << 16 | (FLAC__uint32)data[10] << 8 | (FLAC__uint32)data[11];
picture->height = (FLAC__uint32)data[12] << 24 | (FLAC__uint32)data[13] << 16 | (FLAC__uint32)data[14] << 8 | (FLAC__uint32)data[15];
@ -173,8 +176,6 @@ static FLAC__bool local__extract_resolution_color_info_(FLAC__StreamMetadata_Pic
picture->colors = clen / 3u;
return true;
}
else if(clen + 12 > len)
return false;
else {
data += 12 + clen;
len -= 12 + clen;
@ -274,7 +275,8 @@ static const char *error_messages[] = {
"unable to guess MIME type from file, user must set explicitly",
"type 1 icon must be a 32x32 pixel PNG",
"file not found", /* currently unused */
"file is too large"
"file is too large",
"empty file"
};
static const char * read_file (const char * filepath, FLAC__StreamMetadata * obj)
@ -287,6 +289,9 @@ static const char * read_file (const char * filepath, FLAC__StreamMetadata * obj
if (size < 0)
return error_messages[5];
if (size == 0)
return error_messages[12];
if (size >= (FLAC__off_t)(1u << FLAC__STREAM_METADATA_LENGTH_LEN)) /* actual limit is less because of other fields in the PICTURE metadata block */
return error_messages[11];
@ -399,7 +404,9 @@ FLAC__StreamMetadata *grabbag__picture_parse_specification(const char *spec, con
*error_message = error_messages[1];
else { /* 'spec' points to filename/URL */
if(0 == strcmp(obj->data.picture.mime_type, "-->")) { /* magic MIME type means URL */
if(!FLAC__metadata_object_picture_set_data(obj, (FLAC__byte*)spec, strlen(spec), /*copy=*/true))
if(strlen(spec) == 0)
*error_message = error_messages[1];
else if(!FLAC__metadata_object_picture_set_data(obj, (FLAC__byte*)spec, strlen(spec), /*copy=*/true))
*error_message = error_messages[0];
else if(obj->data.picture.width == 0 || obj->data.picture.height == 0 || obj->data.picture.depth == 0)
*error_message = error_messages[3];