Revoke support for strxfrm() that write past the specified array length.

This formalizes a decision implicit in commit
4ea51cdfe85ceef8afabceb03c446574daa0ac23 and adds clean detection of
affected systems.  Vendor updates are available for each such known bug.
Back-patch to 9.5, where the aforementioned commit first appeared.

diff --git a/src/backend/main/main.c b/src/backend/main/main.c
index 2ecadd660cfda5fd16524e818e9cd528bd1d4967..4fad6f3dc5545452fb336f6169a6c1934bce8977 100644 (file)
--- a/src/backend/main/main.c
+++ b/src/backend/main/main.c
@@ -149,6 +149,8 @@ main(int argc, char *argv[])
     */
    unsetenv("LC_ALL");
 
+   check_strxfrm_bug();
+
    /*
     * Catch standard options before doing much else, in particular before we
     * insist on not being root.

diff --git a/src/backend/utils/adt/pg_locale.c b/src/backend/utils/adt/pg_locale.c
index 84215e07a772a43defac8e9aa9880b83edd4557f..d91959ea7f8401366ee43510126e471b987e9d62 100644 (file)
--- a/src/backend/utils/adt/pg_locale.c
+++ b/src/backend/utils/adt/pg_locale.c
@@ -854,6 +854,64 @@ IsoLocaleName(const char *winlocname)
 #endif   /* WIN32 && LC_MESSAGES */
 
 
+/*
+ * Detect aging strxfrm() implementations that, in a subset of locales, write
+ * past the specified buffer length.  Affected users must update OS packages
+ * before using PostgreSQL 9.5 or later.
+ *
+ * Assume that the bug can come and go from one postmaster startup to another
+ * due to physical replication among diverse machines.  Assume that the bug's
+ * presence will not change during the life of a particular postmaster.  Given
+ * those assumptions, call this no less than once per postmaster startup per
+ * LC_COLLATE setting used.  No known-affected system offers strxfrm_l(), so
+ * there is no need to consider pg_collation locales.
+ */
+void
+check_strxfrm_bug(void)
+{
+   char        buf[32];
+   const int   canary = 0x7F;
+   bool        ok = true;
+
+   /*
+    * Given a two-byte ASCII string and length limit 7, 8 or 9, Solaris 10
+    * 05/08 returns 18 and modifies 10 bytes.  It respects limits above or
+    * below that range.
+    *
+    * The bug is present in Solaris 8 as well; it is absent in Solaris 10
+    * 01/13 and Solaris 11.2.  Affected locales include is_IS.ISO8859-1,
+    * en_US.UTF-8, en_US.ISO8859-1, and ru_RU.KOI8-R.  Unaffected locales
+    * include de_DE.UTF-8, de_DE.ISO8859-1, zh_TW.UTF-8, and C.
+    */
+   buf[7] = canary;
+   (void) strxfrm(buf, "ab", 7);
+   if (buf[7] != canary)
+       ok = false;
+
+   /*
+    * illumos bug #1594 was present in the source tree from 2010-10-11 to
+    * 2012-02-01.  Given an ASCII string of any length and length limit 1,
+    * affected systems ignore the length limit and modify a number of bytes
+    * one less than the return value.  The problem inputs for this bug do not
+    * overlap those for the Solaris bug, hence a distinct test.
+    *
+    * Affected systems include smartos-20110926T021612Z.  Affected locales
+    * include en_US.ISO8859-1 and en_US.UTF-8.  Unaffected locales include C.
+    */
+   buf[1] = canary;
+   (void) strxfrm(buf, "a", 1);
+   if (buf[1] != canary)
+       ok = false;
+
+   if (!ok)
+       ereport(ERROR,
+               (errcode(ERRCODE_SYSTEM_ERROR),
+                errmsg_internal("strxfrm(), in locale \"%s\", writes past the specified array length",
+                                setlocale(LC_COLLATE, NULL)),
+                errhint("Apply system library package updates.")));
+}
+
+
 /*
  * Cache mechanism for collation information.
  *

diff --git a/src/backend/utils/adt/selfuncs.c b/src/backend/utils/adt/selfuncs.c
index 04ed07b762df62734d66bc8bc27796ac167c6d70..64b6ae4838f2438ec7a36c3a838180c60b0f35aa 100644 (file)
--- a/src/backend/utils/adt/selfuncs.c
+++ b/src/backend/utils/adt/selfuncs.c
@@ -3932,16 +3932,8 @@ convert_string_datum(Datum value, Oid typid)
        size_t xfrmlen2 PG_USED_FOR_ASSERTS_ONLY;
 
        /*
-        * Note: originally we guessed at a suitable output buffer size, and
-        * only needed to call strxfrm twice if our guess was too small.
-        * However, it seems that some versions of Solaris have buggy strxfrm
-        * that can write past the specified buffer length in that scenario.
-        * So, do it the dumb way for portability.
-        *
-        * Yet other systems (e.g., glibc) sometimes return a smaller value
-        * from the second call than the first; thus the Assert must be <= not
-        * == as you'd expect.  Can't any of these people program their way
-        * out of a paper bag?
+        * XXX: We could guess at a suitable output buffer size and only call
+        * strxfrm twice if our guess is too small.
         *
         * XXX: strxfrm doesn't support UTF-8 encoding on Win32, it can return
         * bogus data or set an error. This is not really a problem unless it
@@ -3974,6 +3966,11 @@ convert_string_datum(Datum value, Oid typid)
 #endif
        xfrmstr = (char *) palloc(xfrmlen + 1);
        xfrmlen2 = strxfrm(xfrmstr, val, xfrmlen + 1);
+
+       /*
+        * Some systems (e.g., glibc) can return a smaller value from the
+        * second call than the first; thus the Assert must be <= not ==.
+        */
        Assert(xfrmlen2 <= xfrmlen);
        pfree(val);
        val = xfrmstr;

diff --git a/src/backend/utils/init/postinit.c b/src/backend/utils/init/postinit.c
index 0f04f28116696d2f109909d499cc8ee61e2c0028..7b1971478bbc4474e2b4d3a1f602059983e027cf 100644 (file)
--- a/src/backend/utils/init/postinit.c
+++ b/src/backend/utils/init/postinit.c
@@ -391,6 +391,8 @@ CheckMyDatabase(const char *name, bool am_superuser)
    SetConfigOption("lc_collate", collate, PGC_INTERNAL, PGC_S_OVERRIDE);
    SetConfigOption("lc_ctype", ctype, PGC_INTERNAL, PGC_S_OVERRIDE);
 
+   check_strxfrm_bug();
+
    ReleaseSysCache(tup);
 }
 

diff --git a/src/include/utils/pg_locale.h b/src/include/utils/pg_locale.h
index 3b5613852bf8c34735e349d6ac97b25f0822d43b..8e91033a41dd615ee16495dd8002457b9b411b8d 100644 (file)
--- a/src/include/utils/pg_locale.h
+++ b/src/include/utils/pg_locale.h
@@ -44,6 +44,7 @@ extern void assign_locale_time(const char *newval, void *extra);
 
 extern bool check_locale(int category, const char *locale, char **canonname);
 extern char *pg_perm_setlocale(int category, const char *locale);
+extern void check_strxfrm_bug(void);
 
 extern bool lc_collate_is_c(Oid collation);
 extern bool lc_ctype_is_c(Oid collation);