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json: Reject invalid \uXXXX, fix \u0000 

The JSON parser translates invalid \uXXXX to garbage instead of
rejecting it, and swallows \u0000.

Fix by using mod_utf8_encode() instead of flawed wchar_to_utf8().

Valid surrogate pairs are now differently broken: they're rejected
instead of translated to garbage.  The next commit will fix them.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20180823164025.12553-29-armbru@redhat.com>
This commit is contained in:
Markus Armbruster 2018-08-23 18:39:55 +02:00
parent de6decfe8e
commit 46a628b139
2 changed files with 17 additions and 59 deletions
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35
qobject/json-parser.c
View File

@ -64,34 +64,6 @@ static void GCC_FMT_ATTR(3, 4) parse_error(JSONParserContext *ctxt,
error_setg(&ctxt->err, "JSON parse error, %s", message);
}
/**
* String helpers
*
* These helpers are used to unescape strings.
*/
static void wchar_to_utf8(uint16_t wchar, char *buffer, size_t buffer_length)
{
if (wchar <= 0x007F) {
BUG_ON(buffer_length < 2);
buffer[0] = wchar & 0x7F;
buffer[1] = 0;
} else if (wchar <= 0x07FF) {
BUG_ON(buffer_length < 3);
buffer[0] = 0xC0 | ((wchar >> 6) & 0x1F);
buffer[1] = 0x80 | (wchar & 0x3F);
buffer[2] = 0;
} else {
BUG_ON(buffer_length < 4);
buffer[0] = 0xE0 | ((wchar >> 12) & 0x0F);
buffer[1] = 0x80 | ((wchar >> 6) & 0x3F);
buffer[2] = 0x80 | (wchar & 0x3F);
buffer[3] = 0;
}
}
static int hex2decimal(char ch)
{
if (ch >= '0' && ch <= '9') {
@ -197,7 +169,12 @@ static QString *parse_string(JSONParserContext *ctxt, JSONToken *token)
ptr++;
}
wchar_to_utf8(cp, utf8_buf, sizeof(utf8_buf));
if (mod_utf8_encode(utf8_buf, sizeof(utf8_buf), cp) < 0) {
parse_error(ctxt, token,
"\\u%.4s is not a valid Unicode character",
ptr - 3);
goto out;
}
qstring_append(str, utf8_buf);
break;
default:

41
tests/check-qjson.c
View File

@ -64,7 +64,7 @@ static void escaped_string(void)
{ "triple byte utf-8 \\u20AC", "triple byte utf-8 \xe2\x82\xac" },
{ "quadruple byte utf-8 \\uD834\\uDD1E", /* U+1D11E */
/* bug: want \xF0\x9D\x84\x9E */
"quadruple byte utf-8 \xED\xA0\xB4\xED\xB4\x9E", .skip = 1 },
NULL },
{ "\\", NULL },
{ "\\z", NULL },
{ "\\ux", NULL },
@ -72,35 +72,16 @@ static void escaped_string(void)
{ "\\u12x", NULL },
{ "\\u123x", NULL },
{ "\\u12345", "\341\210\2645" },
{ "\\u0000x", "x", .skip = 1}, /* bug: want \xC0\x80x */
{ "unpaired leading surrogate \\uD800",
/* bug: not rejected */
"unpaired leading surrogate \355\240\200", .skip = 1 },
{ "unpaired leading surrogate \\uD800\\uCAFE",
/* bug: not rejected */
"unpaired leading surrogate \355\240\200\354\253\276", .skip = 1 },
{ "unpaired leading surrogate \\uD800\\uD801\\uDC02",
/* bug: not rejected */
"unpaired leading surrogate \355\240\200\355\240\201\355\260\202",
.skip = 1 },
{ "unpaired trailing surrogate \\uDC00",
/* bug: not rejected */
"unpaired trailing surrogate \355\260\200", .skip = 1},
{ "backward surrogate pair \\uDC00\\uD800",
/* bug: not rejected */
"backward surrogate pair \355\260\200\355\240\200", .skip = 1},
{ "noncharacter U+FDD0 \\uFDD0",
/* bug: not rejected */
"noncharacter U+FDD0 \xEF\xB7\x90", .skip = 1},
{ "noncharacter U+FDEF \\uFDEF",
/* bug: not rejected */
"noncharacter U+FDEF \xEF\xB7\xAF", .skip = 1},
{ "noncharacter U+1FFFE \\uD87F\\uDFFE",
/* bug: not rejected */
"noncharacter U+1FFFE \xED\xA1\xBF\xED\xBF\xBE", .skip = 1},
{ "noncharacter U+10FFFF \\uDC3F\\uDFFF",
/* bug: not rejected */
"noncharacter U+10FFFF \xED\xB0\xBF\xED\xBF\xBF", .skip = 1},
{ "\\u0000x", "\xC0\x80x" },
{ "unpaired leading surrogate \\uD800", NULL },
{ "unpaired leading surrogate \\uD800\\uCAFE", NULL },
{ "unpaired leading surrogate \\uD800\\uD801\\uDC02", NULL },
{ "unpaired trailing surrogate \\uDC00", NULL },
{ "backward surrogate pair \\uDC00\\uD800", NULL },
{ "noncharacter U+FDD0 \\uFDD0", NULL },
{ "noncharacter U+FDEF \\uFDEF", NULL },
{ "noncharacter U+1FFFE \\uD87F\\uDFFE", NULL },
{ "noncharacter U+10FFFF \\uDC3F\\uDFFF", NULL },
{}
};
int i, j;