From be8b06c364db315258fb074e9bfbf5db04ab2c5f Mon Sep 17 00:00:00 2001
From: Noah Misch <noah@leadboat.com>
Date: Wed, 8 Jul 2015 20:44:21 -0400
Subject: [PATCH] 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.
---
src/backend/main/main.c | 2 ++
src/backend/utils/adt/pg_locale.c | 58 +++++++++++++++++++++++++++++++
src/backend/utils/adt/selfuncs.c | 17 ++++-----
src/backend/utils/init/postinit.c | 2 ++
src/include/utils/pg_locale.h | 1 +
5 files changed, 70 insertions(+), 10 deletions(-)
diff --git a/src/backend/main/main.c b/src/backend/main/main.c
index 2ecadd660cf..4fad6f3dc55 100644
--- 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 84215e07a77..d91959ea7f8 100644
--- 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 04ed07b762d..64b6ae4838f 100644
--- 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 0f04f281166..7b1971478bb 100644
--- 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 3b5613852bf..8e91033a41d 100644
--- 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);
--
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