From e59f39d40397645477b959255aedfa17a7c9c779 Mon Sep 17 00:00:00 2001 From: Markus Armbruster Date: Thu, 23 Aug 2018 18:39:49 +0200 Subject: [PATCH] json: Reject invalid UTF-8 sequences 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 Reviewed-by: Eric Blake Message-Id: <20180823164025.12553-23-armbru@redhat.com> --- include/qemu/unicode.h | 1 + qobject/json-parser.c | 20 ++++-- tests/check-qjson.c | 137 ++++++++++++++--------------------------- util/unicode.c | 69 ++++++++++++++++++--- 4 files changed, 122 insertions(+), 105 deletions(-) diff --git a/include/qemu/unicode.h b/include/qemu/unicode.h index 71c72db461..7fa10b8e60 100644 --- a/include/qemu/unicode.h +++ b/include/qemu/unicode.h @@ -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 diff --git a/qobject/json-parser.c b/qobject/json-parser.c index 164b86769b..0e232ff101 100644 --- a/qobject/json-parser.c +++ b/qobject/json-parser.c @@ -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); } } diff --git a/tests/check-qjson.c b/tests/check-qjson.c index 69f5a187c9..71c77d2f70 100644 --- a/tests/check-qjson.c +++ b/tests/check-qjson.c @@ -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); } diff --git a/util/unicode.c b/util/unicode.c index a812a35171..8580bc598b 100644 --- a/util/unicode.c +++ b/util/unicode.c @@ -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; +}