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json: Reject invalid UTF-8 sequences

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We reject bytes that can't occur in valid UTF-8 (\xC0..\xC1,
\xF5..\xFF in the lexer.  That's insufficient; there's plenty of
invalid UTF-8 not containing these bytes, as demonstrated by
check-qjson:

* Malformed sequences

  - Unexpected continuation bytes

  - Missing continuation bytes after start bytes other than
    \xC0..\xC1, \xF5..\xFD.

* Overlong sequences with start bytes other than \xC0..\xC1,
  \xF5..\xFD.

* Invalid code points

Fixing this in the lexer would be bothersome.  Fixing it in the parser
is straightforward, so do that.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20180823164025.12553-23-armbru@redhat.com>
This commit is contained in:
Markus Armbruster 2018-08-23 18:39:49 +02:00
parent a89d3104a2
commit e59f39d403
4 changed files with 122 additions and 105 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
include/qemu/unicode.h
View File

@ -2,5 +2,6 @@
#define QEMU_UNICODE_H
int mod_utf8_codepoint(const char *s, size_t n, char **end);
ssize_t mod_utf8_encode(char buf[], size_t bufsz, int codepoint);
#endif

20
qobject/json-parser.c
View File

@ -13,6 +13,7 @@
#include "qemu/osdep.h"
#include "qemu/cutils.h"
#include "qemu/unicode.h"
#include "qapi/error.h"
#include "qemu-common.h"
#include "qapi/qmp/qbool.h"
@ -133,6 +134,10 @@ static QString *qstring_from_escaped_str(JSONParserContext *ctxt,
const char *ptr = token->str;
QString *str;
char quote;
int cp;
char *end;
ssize_t len;
char utf8_buf[5];
assert(*ptr == '"' || *ptr == '\'');
quote = *ptr++;
@ -194,12 +199,15 @@ static QString *qstring_from_escaped_str(JSONParserContext *ctxt,
goto out;
}
} else {
char dummy[2];
dummy[0] = *ptr++;
dummy[1] = 0;
qstring_append(str, dummy);
cp = mod_utf8_codepoint(ptr, 6, &end);
if (cp <= 0) {
parse_error(ctxt, token, "invalid UTF-8 sequence in string");
goto out;
}
ptr = end;
len = mod_utf8_encode(utf8_buf, sizeof(utf8_buf), cp);
assert(len >= 0);
qstring_append(str, utf8_buf);
}
}

137
tests/check-qjson.c
View File

@ -152,13 +152,6 @@ static void string_with_quotes(void)
static void utf8_string(void)
{
/*
* FIXME Current behavior for invalid UTF-8 sequences is
* incorrect. This test expects current, incorrect results.
* They're all marked "bug:" below, and are to be replaced by
* correct ones as the bugs get fixed.
*
* The JSON parser rejects some, but not all invalid sequences.
*
* Problem: we can't easily deal with embedded U+0000. Parsing
* the JSON string "this \\u0000" is fun" yields "this \0 is fun",
* which gets misinterpreted as NUL-terminated "this ". We should
@ -177,12 +170,6 @@ static void utf8_string(void)
/* Expected unparse output, defaults to @json_in */
const char *json_out;
} test_cases[] = {
/*
* Bug markers used here:
* - bug: not rejected
* JSON parser fails to reject invalid sequence(s)
*/
/* 0 Control characters */
{
/*
@ -330,7 +317,7 @@ static void utf8_string(void)
{
/* first one beyond Unicode range: U+110000 */
"\xF4\x90\x80\x80",
"\xF4\x90\x80\x80",
NULL,
"\\uFFFD",
},
/* 3 Malformed sequences */
@ -338,49 +325,49 @@ static void utf8_string(void)
/* 3.1.1 First continuation byte */
{
"\x80",
"\x80", /* bug: not rejected */
NULL,
"\\uFFFD",
},
/* 3.1.2 Last continuation byte */
{
"\xBF",
"\xBF", /* bug: not rejected */
NULL,
"\\uFFFD",
},
/* 3.1.3 2 continuation bytes */
{
"\x80\xBF",
"\x80\xBF", /* bug: not rejected */
NULL,
"\\uFFFD\\uFFFD",
},
/* 3.1.4 3 continuation bytes */
{
"\x80\xBF\x80",
"\x80\xBF\x80", /* bug: not rejected */
NULL,
"\\uFFFD\\uFFFD\\uFFFD",
},
/* 3.1.5 4 continuation bytes */
{
"\x80\xBF\x80\xBF",
"\x80\xBF\x80\xBF", /* bug: not rejected */
NULL,
"\\uFFFD\\uFFFD\\uFFFD\\uFFFD",
},
/* 3.1.6 5 continuation bytes */
{
"\x80\xBF\x80\xBF\x80",
"\x80\xBF\x80\xBF\x80", /* bug: not rejected */
NULL,
"\\uFFFD\\uFFFD\\uFFFD\\uFFFD\\uFFFD",
},
/* 3.1.7 6 continuation bytes */
{
"\x80\xBF\x80\xBF\x80\xBF",
"\x80\xBF\x80\xBF\x80\xBF", /* bug: not rejected */
NULL,
"\\uFFFD\\uFFFD\\uFFFD\\uFFFD\\uFFFD\\uFFFD",
},
/* 3.1.8 7 continuation bytes */
{
"\x80\xBF\x80\xBF\x80\xBF\x80",
"\x80\xBF\x80\xBF\x80\xBF\x80", /* bug: not rejected */
NULL,
"\\uFFFD\\uFFFD\\uFFFD\\uFFFD\\uFFFD\\uFFFD\\uFFFD",
},
/* 3.1.9 Sequence of all 64 possible continuation bytes */
@ -393,16 +380,7 @@ static void utf8_string(void)
"\xA8\xA9\xAA\xAB\xAC\xAD\xAE\xAF"
"\xB0\xB1\xB2\xB3\xB4\xB5\xB6\xB7"
"\xB8\xB9\xBA\xBB\xBC\xBD\xBE\xBF",
/* bug: not rejected */
"\x80\x81\x82\x83\x84\x85\x86\x87"
"\x88\x89\x8A\x8B\x8C\x8D\x8E\x8F"
"\x90\x91\x92\x93\x94\x95\x96\x97"
"\x98\x99\x9A\x9B\x9C\x9D\x9E\x9F"
"\xA0\xA1\xA2\xA3\xA4\xA5\xA6\xA7"
"\xA8\xA9\xAA\xAB\xAC\xAD\xAE\xAF"
"\xB0\xB1\xB2\xB3\xB4\xB5\xB6\xB7"
"\xB8\xB9\xBA\xBB\xBC\xBD\xBE\xBF",
"\\uFFFD\\uFFFD\\uFFFD\\uFFFD\\uFFFD\\uFFFD\\uFFFD\\uFFFD"
NULL,
"\\uFFFD\\uFFFD\\uFFFD\\uFFFD\\uFFFD\\uFFFD\\uFFFD\\uFFFD"
"\\uFFFD\\uFFFD\\uFFFD\\uFFFD\\uFFFD\\uFFFD\\uFFFD\\uFFFD"
"\\uFFFD\\uFFFD\\uFFFD\\uFFFD\\uFFFD\\uFFFD\\uFFFD\\uFFFD"
@ -410,6 +388,7 @@ static void utf8_string(void)
"\\uFFFD\\uFFFD\\uFFFD\\uFFFD\\uFFFD\\uFFFD\\uFFFD\\uFFFD"
"\\uFFFD\\uFFFD\\uFFFD\\uFFFD\\uFFFD\\uFFFD\\uFFFD\\uFFFD"
"\\uFFFD\\uFFFD\\uFFFD\\uFFFD\\uFFFD\\uFFFD\\uFFFD\\uFFFD"
"\\uFFFD\\uFFFD\\uFFFD\\uFFFD\\uFFFD\\uFFFD\\uFFFD\\uFFFD",
},
/* 3.2 Lonely start characters */
/* 3.2.1 All 32 first bytes of 2-byte sequences, followed by space */
@ -418,7 +397,7 @@ static void utf8_string(void)
"\xC8 \xC9 \xCA \xCB \xCC \xCD \xCE \xCF "
"\xD0 \xD1 \xD2 \xD3 \xD4 \xD5 \xD6 \xD7 "
"\xD8 \xD9 \xDA \xDB \xDC \xDD \xDE \xDF ",
NULL, /* bug: accepted partly, see FIXME below */
NULL,
"\\uFFFD \\uFFFD \\uFFFD \\uFFFD \\uFFFD \\uFFFD \\uFFFD \\uFFFD "
"\\uFFFD \\uFFFD \\uFFFD \\uFFFD \\uFFFD \\uFFFD \\uFFFD \\uFFFD "
"\\uFFFD \\uFFFD \\uFFFD \\uFFFD \\uFFFD \\uFFFD \\uFFFD \\uFFFD "
@ -428,16 +407,14 @@ static void utf8_string(void)
{
"\xE0 \xE1 \xE2 \xE3 \xE4 \xE5 \xE6 \xE7 "
"\xE8 \xE9 \xEA \xEB \xEC \xED \xEE \xEF ",
/* bug: not rejected */
"\xE0 \xE1 \xE2 \xE3 \xE4 \xE5 \xE6 \xE7 "
"\xE8 \xE9 \xEA \xEB \xEC \xED \xEE \xEF ",
NULL,
"\\uFFFD \\uFFFD \\uFFFD \\uFFFD \\uFFFD \\uFFFD \\uFFFD \\uFFFD "
"\\uFFFD \\uFFFD \\uFFFD \\uFFFD \\uFFFD \\uFFFD \\uFFFD \\uFFFD ",
},
/* 3.2.3 All 8 first bytes of 4-byte sequences, followed by space */
{
"\xF0 \xF1 \xF2 \xF3 \xF4 \xF5 \xF6 \xF7 ",
NULL, /* bug: accepted partly, see FIXME below */
NULL,
"\\uFFFD \\uFFFD \\uFFFD \\uFFFD \\uFFFD \\uFFFD \\uFFFD \\uFFFD ",
},
/* 3.2.4 All 4 first bytes of 5-byte sequences, followed by space */
@ -462,13 +439,13 @@ static void utf8_string(void)
/* 3.3.2 3-byte sequence with last byte missing (U+0000) */
{
"\xE0\x80",
"\xE0\x80", /* bug: not rejected */
NULL,
"\\uFFFD",
},
/* 3.3.3 4-byte sequence with last byte missing (U+0000) */
{
"\xF0\x80\x80",
"\xF0\x80\x80", /* bug: not rejected */
NULL,
"\\uFFFD",
},
/* 3.3.4 5-byte sequence with last byte missing (U+0000) */
@ -486,13 +463,13 @@ static void utf8_string(void)
/* 3.3.6 2-byte sequence with last byte missing (U+07FF) */
{
"\xDF",
"\xDF", /* bug: not rejected */
NULL,
"\\uFFFD",
},
/* 3.3.7 3-byte sequence with last byte missing (U+FFFF) */
{
"\xEF\xBF",
"\xEF\xBF", /* bug: not rejected */
NULL,
"\\uFFFD",
},
/* 3.3.8 4-byte sequence with last byte missing (U+1FFFFF) */
@ -517,7 +494,7 @@ static void utf8_string(void)
{
"\xC0\xE0\x80\xF0\x80\x80\xF8\x80\x80\x80\xFC\x80\x80\x80\x80"
"\xDF\xEF\xBF\xF7\xBF\xBF\xFB\xBF\xBF\xBF\xFD\xBF\xBF\xBF\xBF",
NULL, /* bug: accepted partly, see FIXME below */
NULL,
"\\uFFFD\\uFFFD\\uFFFD\\uFFFD\\uFFFD"
"\\uFFFD\\uFFFD\\uFFFD\\uFFFD\\uFFFD",
},
@ -546,12 +523,12 @@ static void utf8_string(void)
},
{
"\xE0\x80\xAF",
"\xE0\x80\xAF", /* bug: not rejected */
NULL,
"\\uFFFD",
},
{
"\xF0\x80\x80\xAF",
"\xF0\x80\x80\xAF", /* bug: not rejected */
NULL,
"\\uFFFD",
},
{
@ -579,7 +556,7 @@ static void utf8_string(void)
{
/* \U+07FF */
"\xE0\x9F\xBF",
"\xE0\x9F\xBF", /* bug: not rejected */
NULL,
"\\uFFFD",
},
{
@ -590,7 +567,7 @@ static void utf8_string(void)
* also 2.2.3
*/
"\xF0\x8F\xBF\xBC",
"\xF0\x8F\xBF\xBC", /* bug: not rejected */
NULL,
"\\uFFFD",
},
{
@ -615,13 +592,13 @@ static void utf8_string(void)
{
/* \U+0000 */
"\xE0\x80\x80",
"\xE0\x80\x80", /* bug: not rejected */
NULL,
"\\uFFFD",
},
{
/* \U+0000 */
"\xF0\x80\x80\x80",
"\xF0\x80\x80\x80", /* bug: not rejected */
NULL,
"\\uFFFD",
},
{
@ -641,92 +618,92 @@ static void utf8_string(void)
{
/* \U+D800 */
"\xED\xA0\x80",
"\xED\xA0\x80", /* bug: not rejected */
NULL,
"\\uFFFD",
},
{
/* \U+DB7F */
"\xED\xAD\xBF",
"\xED\xAD\xBF", /* bug: not rejected */
NULL,
"\\uFFFD",
},
{
/* \U+DB80 */
"\xED\xAE\x80",
"\xED\xAE\x80", /* bug: not rejected */
NULL,
"\\uFFFD",
},
{
/* \U+DBFF */
"\xED\xAF\xBF",
"\xED\xAF\xBF", /* bug: not rejected */
NULL,
"\\uFFFD",
},
{
/* \U+DC00 */
"\xED\xB0\x80",
"\xED\xB0\x80", /* bug: not rejected */
NULL,
"\\uFFFD",
},
{
/* \U+DF80 */
"\xED\xBE\x80",
"\xED\xBE\x80", /* bug: not rejected */
NULL,
"\\uFFFD",
},
{
/* \U+DFFF */
"\xED\xBF\xBF",
"\xED\xBF\xBF", /* bug: not rejected */
NULL,
"\\uFFFD",
},
/* 5.2 Paired UTF-16 surrogates */
{
/* \U+D800\U+DC00 */
"\xED\xA0\x80\xED\xB0\x80",
"\xED\xA0\x80\xED\xB0\x80", /* bug: not rejected */
NULL,
"\\uFFFD\\uFFFD",
},
{
/* \U+D800\U+DFFF */
"\xED\xA0\x80\xED\xBF\xBF",
"\xED\xA0\x80\xED\xBF\xBF", /* bug: not rejected */
NULL,
"\\uFFFD\\uFFFD",
},
{
/* \U+DB7F\U+DC00 */
"\xED\xAD\xBF\xED\xB0\x80",
"\xED\xAD\xBF\xED\xB0\x80", /* bug: not rejected */
NULL,
"\\uFFFD\\uFFFD",
},
{
/* \U+DB7F\U+DFFF */
"\xED\xAD\xBF\xED\xBF\xBF",
"\xED\xAD\xBF\xED\xBF\xBF", /* bug: not rejected */
NULL,
"\\uFFFD\\uFFFD",
},
{
/* \U+DB80\U+DC00 */
"\xED\xAE\x80\xED\xB0\x80",
"\xED\xAE\x80\xED\xB0\x80", /* bug: not rejected */
NULL,
"\\uFFFD\\uFFFD",
},
{
/* \U+DB80\U+DFFF */
"\xED\xAE\x80\xED\xBF\xBF",
"\xED\xAE\x80\xED\xBF\xBF", /* bug: not rejected */
NULL,
"\\uFFFD\\uFFFD",
},
{
/* \U+DBFF\U+DC00 */
"\xED\xAF\xBF\xED\xB0\x80",
"\xED\xAF\xBF\xED\xB0\x80", /* bug: not rejected */
NULL,
"\\uFFFD\\uFFFD",
},
{
/* \U+DBFF\U+DFFF */
"\xED\xAF\xBF\xED\xBF\xBF",
"\xED\xAF\xBF\xED\xBF\xBF", /* bug: not rejected */
NULL,
"\\uFFFD\\uFFFD",
},
/* 5.3 Other illegal code positions */
@ -734,25 +711,25 @@ static void utf8_string(void)
{
/* \U+FFFE */
"\xEF\xBF\xBE",
"\xEF\xBF\xBE", /* bug: not rejected */
NULL,
"\\uFFFD",
},
{
/* \U+FFFF */
"\xEF\xBF\xBF",
"\xEF\xBF\xBF", /* bug: not rejected */
NULL,
"\\uFFFD",
},
{
/* U+FDD0 */
"\xEF\xB7\x90",
"\xEF\xB7\x90", /* bug: not rejected */
NULL,
"\\uFFFD",
},
{
/* U+FDEF */
"\xEF\xB7\xAF",
"\xEF\xB7\xAF", /* bug: not rejected */
NULL,
"\\uFFFD",
},
/* Plane 1 .. 16 noncharacters */
@ -774,23 +751,7 @@ static void utf8_string(void)
"\xF3\xAF\xBF\xBE\xF3\xAF\xBF\xBF"
"\xF3\xBF\xBF\xBE\xF3\xBF\xBF\xBF"
"\xF4\x8F\xBF\xBE\xF4\x8F\xBF\xBF",
/* bug: not rejected */
"\xF0\x9F\xBF\xBE\xF0\x9F\xBF\xBF"
"\xF0\xAF\xBF\xBE\xF0\xAF\xBF\xBF"
"\xF0\xBF\xBF\xBE\xF0\xBF\xBF\xBF"
"\xF1\x8F\xBF\xBE\xF1\x8F\xBF\xBF"
"\xF1\x9F\xBF\xBE\xF1\x9F\xBF\xBF"
"\xF1\xAF\xBF\xBE\xF1\xAF\xBF\xBF"
"\xF1\xBF\xBF\xBE\xF1\xBF\xBF\xBF"
"\xF2\x8F\xBF\xBE\xF2\x8F\xBF\xBF"
"\xF2\x9F\xBF\xBE\xF2\x9F\xBF\xBF"
"\xF2\xAF\xBF\xBE\xF2\xAF\xBF\xBF"
"\xF2\xBF\xBF\xBE\xF2\xBF\xBF\xBF"
"\xF3\x8F\xBF\xBE\xF3\x8F\xBF\xBF"
"\xF3\x9F\xBF\xBE\xF3\x9F\xBF\xBF"
"\xF3\xAF\xBF\xBE\xF3\xAF\xBF\xBF"
"\xF3\xBF\xBF\xBE\xF3\xBF\xBF\xBF"
"\xF4\x8F\xBF\xBE\xF4\x8F\xBF\xBF",
NULL,
"\\uFFFD\\uFFFD\\uFFFD\\uFFFD\\uFFFD\\uFFFD\\uFFFD\\uFFFD"
"\\uFFFD\\uFFFD\\uFFFD\\uFFFD\\uFFFD\\uFFFD\\uFFFD\\uFFFD"
"\\uFFFD\\uFFFD\\uFFFD\\uFFFD\\uFFFD\\uFFFD\\uFFFD\\uFFFD"
@ -829,14 +790,6 @@ static void utf8_string(void)
}
in = strndup(tail, end - tail);
str = from_json_str(in, j, NULL);
/*
* FIXME JSON parser accepts invalid sequence
* starting with \xC2..\xF4
*/
if (*in >= '\xC2' && *in <= '\xF4') {
g_free(str);
str = NULL;
}
g_assert(!str);
g_free(in);
}

69
util/unicode.c
View File

@ -13,6 +13,21 @@
#include "qemu/osdep.h"
#include "qemu/unicode.h"
static bool is_valid_codepoint(int codepoint)
{
if (codepoint > 0x10FFFFu) {
return false; /* beyond Unicode range */
}
if ((codepoint >= 0xFDD0 && codepoint <= 0xFDEF)
|| (codepoint & 0xFFFE) == 0xFFFE) {
return false; /* noncharacter */
}
if (codepoint >= 0xD800 && codepoint <= 0xDFFF) {
return false; /* surrogate code point */
}
return true;
}
/**
* mod_utf8_codepoint:
* @s: string encoded in modified UTF-8
@ -83,13 +98,8 @@ int mod_utf8_codepoint(const char *s, size_t n, char **end)
cp <<= 6;
cp |= byte & 0x3F;
}
if (cp > 0x10FFFF) {
cp = -1; /* beyond Unicode range */
} else if ((cp >= 0xFDD0 && cp <= 0xFDEF)
|| (cp & 0xFFFE) == 0xFFFE) {
cp = -1; /* noncharacter */
} else if (cp >= 0xD800 && cp <= 0xDFFF) {
cp = -1; /* surrogate code point */
if (!is_valid_codepoint(cp)) {
cp = -1;
} else if (cp < min_cp[len - 2] && !(cp == 0 && len == 2)) {
cp = -1; /* overlong, not \xC0\x80 */
}
@ -99,3 +109,48 @@ out:
*end = (char *)p;
return cp;
}
/**
* mod_utf8_encode:
* @buf: Destination buffer
* @bufsz: size of @buf, at least 5.
* @codepoint: Unicode codepoint to encode
*
* Convert Unicode codepoint @codepoint to modified UTF-8.
*
* Returns: the length of the UTF-8 sequence on success, -1 when
* @codepoint is invalid.
*/
ssize_t mod_utf8_encode(char buf[], size_t bufsz, int codepoint)
{
assert(bufsz >= 5);
if (!is_valid_codepoint(codepoint)) {
return -1;
}
if (codepoint > 0 && codepoint <= 0x7F) {
buf[0] = codepoint & 0x7F;
buf[1] = 0;
return 1;
}
if (codepoint <= 0x7FF) {
buf[0] = 0xC0 | ((codepoint >> 6) & 0x1F);
buf[1] = 0x80 | (codepoint & 0x3F);
buf[2] = 0;
return 2;
}
if (codepoint <= 0xFFFF) {
buf[0] = 0xE0 | ((codepoint >> 12) & 0x0F);
buf[1] = 0x80 | ((codepoint >> 6) & 0x3F);
buf[2] = 0x80 | (codepoint & 0x3F);
buf[3] = 0;
return 3;
}
buf[0] = 0xF0 | ((codepoint >> 18) & 0x07);
buf[1] = 0x80 | ((codepoint >> 12) & 0x3F);
buf[2] = 0x80 | ((codepoint >> 6) & 0x3F);
buf[3] = 0x80 | (codepoint & 0x3F);
buf[4] = 0;
return 4;
}