From 42f94f56bf9559f0a3cf5f3ffde50655834694ee Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Mon, 7 Jun 2021 14:15:25 -0400 Subject: [PATCH] Fix incautious handling of possibly-miscoded strings in client code. An incorrectly-encoded multibyte character near the end of a string could cause various processing loops to run past the string's terminating NUL, with results ranging from no detectable issue to a program crash, depending on what happens to be in the following memory. This isn't an issue in the server, because we take care to verify the encoding of strings before doing any interesting processing on them. However, that lack of care leaked into client-side code which shouldn't assume that anyone has validated the encoding of its input. Although this is certainly a bug worth fixing, the PG security team elected not to regard it as a security issue, primarily because any untrusted text should be sanitized by PQescapeLiteral or the like before being incorporated into a SQL or psql command. (If an app fails to do so, the same technique can be used to cause SQL injection, with probably much more dire consequences than a mere client-program crash.) Those functions were already made proof against this class of problem, cf CVE-2006-2313. To fix, invent PQmblenBounded() which is like PQmblen() except it won't return more than the number of bytes remaining in the string. In HEAD we can make this a new libpq function, as PQmblen() is. It seems imprudent to change libpq's API in stable branches though, so in the back branches define PQmblenBounded as a macro in the files that need it. (Note that just changing PQmblen's behavior would not be a good idea; notably, it would completely break the escaping functions' defense against this exact problem. So we just want a version for those callers that don't have any better way of handling this issue.) Per private report from houjingyi. Back-patch to all supported branches. --- src/bin/psql/common.c | 26 +++++++++++++------------- src/bin/psql/psqlscanslash.l | 2 +- src/bin/psql/stringutils.c | 6 +++--- src/bin/psql/tab-complete.c | 2 +- src/bin/scripts/common.c | 2 +- src/common/jsonapi.c | 6 +++--- src/common/wchar.c | 15 +++++++++++++++ src/fe_utils/print.c | 3 +++ src/fe_utils/string_utils.c | 9 +++------ src/include/mb/pg_wchar.h | 1 + src/interfaces/libpq/exports.txt | 1 + src/interfaces/libpq/fe-misc.c | 19 +++++++++++++++++-- src/interfaces/libpq/fe-print.c | 2 +- src/interfaces/libpq/fe-protocol3.c | 4 ++-- src/interfaces/libpq/libpq-fe.h | 3 +++ 15 files changed, 68 insertions(+), 33 deletions(-) diff --git a/src/bin/psql/common.c b/src/bin/psql/common.c index 7a95465111ad1..9a00499510929 100644 --- a/src/bin/psql/common.c +++ b/src/bin/psql/common.c @@ -1846,7 +1846,7 @@ skip_white_space(const char *query) while (*query) { - int mblen = PQmblen(query, pset.encoding); + int mblen = PQmblenBounded(query, pset.encoding); /* * Note: we assume the encoding is a superset of ASCII, so that for @@ -1883,7 +1883,7 @@ skip_white_space(const char *query) query++; break; } - query += PQmblen(query, pset.encoding); + query += PQmblenBounded(query, pset.encoding); } } else if (cnestlevel > 0) @@ -1918,7 +1918,7 @@ command_no_begin(const char *query) */ wordlen = 0; while (isalpha((unsigned char) query[wordlen])) - wordlen += PQmblen(&query[wordlen], pset.encoding); + wordlen += PQmblenBounded(&query[wordlen], pset.encoding); /* * Transaction control commands. These should include every keyword that @@ -1949,7 +1949,7 @@ command_no_begin(const char *query) wordlen = 0; while (isalpha((unsigned char) query[wordlen])) - wordlen += PQmblen(&query[wordlen], pset.encoding); + wordlen += PQmblenBounded(&query[wordlen], pset.encoding); if (wordlen == 11 && pg_strncasecmp(query, "transaction", 11) == 0) return true; @@ -1983,7 +1983,7 @@ command_no_begin(const char *query) wordlen = 0; while (isalpha((unsigned char) query[wordlen])) - wordlen += PQmblen(&query[wordlen], pset.encoding); + wordlen += PQmblenBounded(&query[wordlen], pset.encoding); if (wordlen == 8 && pg_strncasecmp(query, "database", 8) == 0) return true; @@ -1999,7 +1999,7 @@ command_no_begin(const char *query) wordlen = 0; while (isalpha((unsigned char) query[wordlen])) - wordlen += PQmblen(&query[wordlen], pset.encoding); + wordlen += PQmblenBounded(&query[wordlen], pset.encoding); } if (wordlen == 5 && pg_strncasecmp(query, "index", 5) == 0) @@ -2010,7 +2010,7 @@ command_no_begin(const char *query) wordlen = 0; while (isalpha((unsigned char) query[wordlen])) - wordlen += PQmblen(&query[wordlen], pset.encoding); + wordlen += PQmblenBounded(&query[wordlen], pset.encoding); if (wordlen == 12 && pg_strncasecmp(query, "concurrently", 12) == 0) return true; @@ -2027,7 +2027,7 @@ command_no_begin(const char *query) wordlen = 0; while (isalpha((unsigned char) query[wordlen])) - wordlen += PQmblen(&query[wordlen], pset.encoding); + wordlen += PQmblenBounded(&query[wordlen], pset.encoding); /* ALTER SYSTEM isn't allowed in xacts */ if (wordlen == 6 && pg_strncasecmp(query, "system", 6) == 0) @@ -2050,7 +2050,7 @@ command_no_begin(const char *query) wordlen = 0; while (isalpha((unsigned char) query[wordlen])) - wordlen += PQmblen(&query[wordlen], pset.encoding); + wordlen += PQmblenBounded(&query[wordlen], pset.encoding); if (wordlen == 8 && pg_strncasecmp(query, "database", 8) == 0) return true; @@ -2065,7 +2065,7 @@ command_no_begin(const char *query) query = skip_white_space(query); wordlen = 0; while (isalpha((unsigned char) query[wordlen])) - wordlen += PQmblen(&query[wordlen], pset.encoding); + wordlen += PQmblenBounded(&query[wordlen], pset.encoding); /* * REINDEX [ TABLE | INDEX ] CONCURRENTLY are not allowed in @@ -2084,7 +2084,7 @@ command_no_begin(const char *query) wordlen = 0; while (isalpha((unsigned char) query[wordlen])) - wordlen += PQmblen(&query[wordlen], pset.encoding); + wordlen += PQmblenBounded(&query[wordlen], pset.encoding); if (wordlen == 12 && pg_strncasecmp(query, "concurrently", 12) == 0) return true; @@ -2104,7 +2104,7 @@ command_no_begin(const char *query) wordlen = 0; while (isalpha((unsigned char) query[wordlen])) - wordlen += PQmblen(&query[wordlen], pset.encoding); + wordlen += PQmblenBounded(&query[wordlen], pset.encoding); if (wordlen == 3 && pg_strncasecmp(query, "all", 3) == 0) return true; @@ -2140,7 +2140,7 @@ is_select_command(const char *query) */ wordlen = 0; while (isalpha((unsigned char) query[wordlen])) - wordlen += PQmblen(&query[wordlen], pset.encoding); + wordlen += PQmblenBounded(&query[wordlen], pset.encoding); if (wordlen == 6 && pg_strncasecmp(query, "select", 6) == 0) return true; diff --git a/src/bin/psql/psqlscanslash.l b/src/bin/psql/psqlscanslash.l index 4bb18f132f4f4..51aa33e1611ef 100644 --- a/src/bin/psql/psqlscanslash.l +++ b/src/bin/psql/psqlscanslash.l @@ -753,7 +753,7 @@ dequote_downcase_identifier(char *str, bool downcase, int encoding) { if (downcase && !inquotes) *cp = pg_tolower((unsigned char) *cp); - cp += PQmblen(cp, encoding); + cp += PQmblenBounded(cp, encoding); } } } diff --git a/src/bin/psql/stringutils.c b/src/bin/psql/stringutils.c index 0acc53801cb4a..3a141cdc2b393 100644 --- a/src/bin/psql/stringutils.c +++ b/src/bin/psql/stringutils.c @@ -143,7 +143,7 @@ strtokx(const char *s, /* okay, we have a quoted token, now scan for the closer */ char thisquote = *p++; - for (; *p; p += PQmblen(p, encoding)) + for (; *p; p += PQmblenBounded(p, encoding)) { if (*p == escape && p[1] != '\0') p++; /* process escaped anything */ @@ -262,7 +262,7 @@ strip_quotes(char *source, char quote, char escape, int encoding) else if (c == escape && src[1] != '\0') src++; /* process escaped character */ - i = PQmblen(src, encoding); + i = PQmblenBounded(src, encoding); while (i--) *dst++ = *src++; } @@ -324,7 +324,7 @@ quote_if_needed(const char *source, const char *entails_quote, else if (strchr(entails_quote, c)) need_quotes = true; - i = PQmblen(src, encoding); + i = PQmblenBounded(src, encoding); while (i--) *dst++ = *src++; } diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c index 109b22acb6ba5..32c1bdfdca743 100644 --- a/src/bin/psql/tab-complete.c +++ b/src/bin/psql/tab-complete.c @@ -4397,7 +4397,7 @@ _complete_from_query(const char *simple_query, while (*pstr) { char_length++; - pstr += PQmblen(pstr, pset.encoding); + pstr += PQmblenBounded(pstr, pset.encoding); } /* Free any prior result */ diff --git a/src/bin/scripts/common.c b/src/bin/scripts/common.c index c86c19eae28b3..79cdc6cf33076 100644 --- a/src/bin/scripts/common.c +++ b/src/bin/scripts/common.c @@ -52,7 +52,7 @@ splitTableColumnsSpec(const char *spec, int encoding, cp++; } else - cp += PQmblen(cp, encoding); + cp += PQmblenBounded(cp, encoding); } *table = pnstrdup(spec, cp - spec); *columns = cp; diff --git a/src/common/jsonapi.c b/src/common/jsonapi.c index 1bf38d7b4295e..d376ab152d48d 100644 --- a/src/common/jsonapi.c +++ b/src/common/jsonapi.c @@ -740,7 +740,7 @@ json_lex_string(JsonLexContext *lex) ch = (ch * 16) + (*s - 'A') + 10; else { - lex->token_terminator = s + pg_encoding_mblen(lex->input_encoding, s); + lex->token_terminator = s + pg_encoding_mblen_bounded(lex->input_encoding, s); return JSON_UNICODE_ESCAPE_FORMAT; } } @@ -846,7 +846,7 @@ json_lex_string(JsonLexContext *lex) default: /* Not a valid string escape, so signal error. */ lex->token_start = s; - lex->token_terminator = s + pg_encoding_mblen(lex->input_encoding, s); + lex->token_terminator = s + pg_encoding_mblen_bounded(lex->input_encoding, s); return JSON_ESCAPING_INVALID; } } @@ -860,7 +860,7 @@ json_lex_string(JsonLexContext *lex) * shown it's not a performance win. */ lex->token_start = s; - lex->token_terminator = s + pg_encoding_mblen(lex->input_encoding, s); + lex->token_terminator = s + pg_encoding_mblen_bounded(lex->input_encoding, s); return JSON_ESCAPING_INVALID; } diff --git a/src/common/wchar.c b/src/common/wchar.c index 6e7d731e020fe..0636b8765ba35 100644 --- a/src/common/wchar.c +++ b/src/common/wchar.c @@ -1911,6 +1911,11 @@ const pg_wchar_tbl pg_wchar_table[] = { /* * Returns the byte length of a multibyte character. + * + * Caution: when dealing with text that is not certainly valid in the + * specified encoding, the result may exceed the actual remaining + * string length. Callers that are not prepared to deal with that + * should use pg_encoding_mblen_bounded() instead. */ int pg_encoding_mblen(int encoding, const char *mbstr) @@ -1920,6 +1925,16 @@ pg_encoding_mblen(int encoding, const char *mbstr) pg_wchar_table[PG_SQL_ASCII].mblen((const unsigned char *) mbstr)); } +/* + * Returns the byte length of a multibyte character; but not more than + * the distance to end of string. + */ +int +pg_encoding_mblen_bounded(int encoding, const char *mbstr) +{ + return strnlen(mbstr, pg_encoding_mblen(encoding, mbstr)); +} + /* * Returns the display length of a multibyte character. */ diff --git a/src/fe_utils/print.c b/src/fe_utils/print.c index 273b1bfe4a49f..d48fcc4a0328d 100644 --- a/src/fe_utils/print.c +++ b/src/fe_utils/print.c @@ -3636,6 +3636,9 @@ strlen_max_width(unsigned char *str, int *target_width, int encoding) curr_width += char_width; str += PQmblen((char *) str, encoding); + + if (str > end) /* Don't overrun invalid string */ + str = end; } *target_width = curr_width; diff --git a/src/fe_utils/string_utils.c b/src/fe_utils/string_utils.c index 5b206c7481d79..3efee4e7eed7f 100644 --- a/src/fe_utils/string_utils.c +++ b/src/fe_utils/string_utils.c @@ -1072,12 +1072,9 @@ patternToSQLRegex(int encoding, PQExpBuffer dbnamebuf, PQExpBuffer schemabuf, appendPQExpBufferChar(curbuf, '\\'); else if (ch == '[' && cp[1] == ']') appendPQExpBufferChar(curbuf, '\\'); - i = PQmblen(cp, encoding); - while (i-- && *cp) - { - appendPQExpBufferChar(curbuf, *cp); - cp++; - } + i = PQmblenBounded(cp, encoding); + while (i--) + appendPQExpBufferChar(curbuf, *cp++); } } appendPQExpBufferStr(curbuf, ")$"); diff --git a/src/include/mb/pg_wchar.h b/src/include/mb/pg_wchar.h index 0f31e683189d7..d93ccac263338 100644 --- a/src/include/mb/pg_wchar.h +++ b/src/include/mb/pg_wchar.h @@ -574,6 +574,7 @@ extern int pg_valid_server_encoding_id(int encoding); * earlier in this file are also available from libpgcommon. */ extern int pg_encoding_mblen(int encoding, const char *mbstr); +extern int pg_encoding_mblen_bounded(int encoding, const char *mbstr); extern int pg_encoding_dsplen(int encoding, const char *mbstr); extern int pg_encoding_verifymbchar(int encoding, const char *mbstr, int len); extern int pg_encoding_verifymbstr(int encoding, const char *mbstr, int len); diff --git a/src/interfaces/libpq/exports.txt b/src/interfaces/libpq/exports.txt index a00701f2c5fe6..9ef99f6de127b 100644 --- a/src/interfaces/libpq/exports.txt +++ b/src/interfaces/libpq/exports.txt @@ -184,3 +184,4 @@ PQexitPipelineMode 181 PQpipelineSync 182 PQpipelineStatus 183 PQtraceSetFlags 184 +PQmblenBounded 185 diff --git a/src/interfaces/libpq/fe-misc.c b/src/interfaces/libpq/fe-misc.c index b347d7f847937..9a2a97029340f 100644 --- a/src/interfaces/libpq/fe-misc.c +++ b/src/interfaces/libpq/fe-misc.c @@ -1180,8 +1180,13 @@ pqSocketPoll(int sock, int forRead, int forWrite, time_t end_time) */ /* - * returns the byte length of the character beginning at s, using the + * Returns the byte length of the character beginning at s, using the * specified encoding. + * + * Caution: when dealing with text that is not certainly valid in the + * specified encoding, the result may exceed the actual remaining + * string length. Callers that are not prepared to deal with that + * should use PQmblenBounded() instead. */ int PQmblen(const char *s, int encoding) @@ -1190,7 +1195,17 @@ PQmblen(const char *s, int encoding) } /* - * returns the display length of the character beginning at s, using the + * Returns the byte length of the character beginning at s, using the + * specified encoding; but not more than the distance to end of string. + */ +int +PQmblenBounded(const char *s, int encoding) +{ + return strnlen(s, pg_encoding_mblen(encoding, s)); +} + +/* + * Returns the display length of the character beginning at s, using the * specified encoding. */ int diff --git a/src/interfaces/libpq/fe-print.c b/src/interfaces/libpq/fe-print.c index 94219b1825bcb..fc7d84844e104 100644 --- a/src/interfaces/libpq/fe-print.c +++ b/src/interfaces/libpq/fe-print.c @@ -365,7 +365,7 @@ do_field(const PQprintOpt *po, const PGresult *res, /* Detect whether field contains non-numeric data */ char ch = '0'; - for (p = pval; *p; p += PQmblen(p, res->client_encoding)) + for (p = pval; *p; p += PQmblenBounded(p, res->client_encoding)) { ch = *p; if (!((ch >= '0' && ch <= '9') || diff --git a/src/interfaces/libpq/fe-protocol3.c b/src/interfaces/libpq/fe-protocol3.c index b45fb7e70593a..2e8330534873a 100644 --- a/src/interfaces/libpq/fe-protocol3.c +++ b/src/interfaces/libpq/fe-protocol3.c @@ -1296,7 +1296,7 @@ reportErrorPosition(PQExpBuffer msg, const char *query, int loc, int encoding) if (w <= 0) w = 1; scroffset += w; - qoffset += pg_encoding_mblen(encoding, &wquery[qoffset]); + qoffset += PQmblenBounded(&wquery[qoffset], encoding); } else { @@ -1364,7 +1364,7 @@ reportErrorPosition(PQExpBuffer msg, const char *query, int loc, int encoding) * width. */ scroffset = 0; - for (; i < msg->len; i += pg_encoding_mblen(encoding, &msg->data[i])) + for (; i < msg->len; i += PQmblenBounded(&msg->data[i], encoding)) { int w = pg_encoding_dsplen(encoding, &msg->data[i]); diff --git a/src/interfaces/libpq/libpq-fe.h b/src/interfaces/libpq/libpq-fe.h index 227adde5a5e42..845b4c04c9c2f 100644 --- a/src/interfaces/libpq/libpq-fe.h +++ b/src/interfaces/libpq/libpq-fe.h @@ -625,6 +625,9 @@ extern int PQlibVersion(void); /* Determine length of multibyte encoded char at *s */ extern int PQmblen(const char *s, int encoding); +/* Same, but not more than the distance to the end of string s */ +extern int PQmblenBounded(const char *s, int encoding); + /* Determine display length of multibyte encoded char at *s */ extern int PQdsplen(const char *s, int encoding);