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.

diff --git a/src/bin/psql/common.c b/src/bin/psql/common.c
index 8169672a2857d877c60279e2306f418fd80851e6..d6909cf1c5196aa9523f790dfd9be9cdf0eb6256 100644 (file)
--- a/src/bin/psql/common.c
+++ b/src/bin/psql/common.c
@@ -28,6 +28,8 @@
 #include "fe_utils/mbprint.h"
 
 
+#define PQmblenBounded(s, e)  strnlen(s, PQmblen(s, e))
+
 static bool ExecQueryUsingCursor(const char *query, double *elapsed_msec);
 static bool command_no_begin(const char *query);
 static bool is_select_command(const char *query);
@@ -1700,7 +1702,7 @@ 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
@@ -1737,7 +1739,7 @@ skip_white_space(const char *query)
                    query++;
                    break;
                }
-               query += PQmblen(query, pset.encoding);
+               query += PQmblenBounded(query, pset.encoding);
            }
        }
        else if (cnestlevel > 0)
@@ -1772,7 +1774,7 @@ 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
@@ -1803,7 +1805,7 @@ 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;
@@ -1837,7 +1839,7 @@ 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;
@@ -1853,7 +1855,7 @@ 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)
@@ -1864,7 +1866,7 @@ 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;
@@ -1881,7 +1883,7 @@ 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)
@@ -1904,7 +1906,7 @@ 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;
@@ -1922,7 +1924,7 @@ 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;
@@ -1942,7 +1944,7 @@ 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;
@@ -1978,7 +1980,7 @@ 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 afa1d3be96c86871424bb3951ecab9000e9f1476..2a86fa4e33af45a12a1b011ba8fb2459e8394dac 100644 (file)
--- a/src/bin/psql/psqlscanslash.l
+++ b/src/bin/psql/psqlscanslash.l
@@ -26,6 +26,8 @@
 %{
 #include "fe_utils/psqlscan_int.h"
 
+#define PQmblenBounded(s, e)  strnlen(s, PQmblen(s, e))
+
 /*
  * We must have a typedef YYSTYPE for yylex's first argument, but this lexer
  * doesn't presently make use of that argument, so just declare it as int.
@@ -681,7 +683,7 @@ 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 9c6034cf8244e3db4658069b41da8e6e527d881d..a8dcee2288f643832aa759200b6a6478f5fd0618 100644 (file)
--- a/src/bin/psql/stringutils.c
+++ b/src/bin/psql/stringutils.c
@@ -12,6 +12,8 @@
 #include "common.h"
 #include "stringutils.h"
 
+#define PQmblenBounded(s, e)  strnlen(s, PQmblen(s, e))
+
 
 /*
  * Replacement for strtok() (a.k.a. poor man's flex)
@@ -143,7 +145,7 @@ 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 +264,7 @@ 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++;
    }
@@ -322,7 +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 272fca1d0ba935d3397c3252ffd025cf62d73fc4..aaa57eedec19ad60955711acb2751bf02594a11d 100644 (file)
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -57,6 +57,8 @@ extern char *filename_completion_function();
 #define completion_matches rl_completion_matches
 #endif
 
+#define PQmblenBounded(s, e)  strnlen(s, PQmblen(s, e))
+
 /* word break characters */
 #define WORD_BREAKS        "\t\n@$><=;|&{() "
 
@@ -3308,7 +3310,7 @@ _complete_from_query(int is_schema_query, const char *text, int state)
        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 64bf1f4227052301435c3904342b26c0bab980da..49d7ebe8379838a4cd7875481d5f00d46d225bd1 100644 (file)
--- a/src/bin/scripts/common.c
+++ b/src/bin/scripts/common.c
@@ -21,6 +21,8 @@
 #include "fe_utils/connect.h"
 #include "fe_utils/string_utils.h"
 
+#define PQmblenBounded(s, e)  strnlen(s, PQmblen(s, e))
+
 
 static PGcancel *volatile cancelConn = NULL;
 bool       CancelRequested = false;
@@ -304,7 +306,7 @@ split_table_columns_spec(const char *spec, int encoding,
            cp++;
        }
        else
-           cp += PQmblen(cp, encoding);
+           cp += PQmblenBounded(cp, encoding);
    }
    *table = pg_strdup(spec);
    (*table)[cp - spec] = '\0'; /* no strndup */

diff --git a/src/fe_utils/print.c b/src/fe_utils/print.c
index 5b56d31faa3e987f0239bbaa61e7b9731189590a..6f773b93b29d57b62f1d307dc4822c58353d401e 100644 (file)
--- a/src/fe_utils/print.c
+++ b/src/fe_utils/print.c
@@ -3527,6 +3527,9 @@ 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/interfaces/libpq/fe-print.c b/src/interfaces/libpq/fe-print.c
index e596a514087388743994f8f35310e73cd1231cd1..4988778f814f1056b2ce9d0b5688621340ec10af 100644 (file)
--- a/src/interfaces/libpq/fe-print.c
+++ b/src/interfaces/libpq/fe-print.c
@@ -36,6 +36,7 @@
 #include "libpq-fe.h"
 #include "libpq-int.h"
 
+#define PQmblenBounded(s, e)  strnlen(s, PQmblen(s, e))
 
 static void do_field(const PQprintOpt *po, const PGresult *res,
         const int i, const int j, const int fs_len,
@@ -358,7 +359,7 @@ 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 013274f6111b5efaf4f1c4b0614dc3781a137522..8e399d597c1018a1060bbdf504aeba516206d0fc 100644 (file)
--- a/src/interfaces/libpq/fe-protocol3.c
+++ b/src/interfaces/libpq/fe-protocol3.c
@@ -42,6 +42,8 @@
    ((id) == 'T' || (id) == 'D' || (id) == 'd' || (id) == 'V' || \
     (id) == 'E' || (id) == 'N' || (id) == 'A')
 
+#define PQmblenBounded(s, e)  strnlen(s, PQmblen(s, e))
+
 
 static void handleSyncLoss(PGconn *conn, char id, int msgLength);
 static int getRowDescriptions(PGconn *conn, int msgLength);
@@ -1228,7 +1230,7 @@ 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
        {
@@ -1296,7 +1298,7 @@ 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]);