Back-patch pg_encoding_verifymbstr()/pg_encoding_verifymbchar() to v13.

A security fix will need those functions, so back-patch the v14+ functions to
v13.

When commit b80e10638e36b9d2f0b39170c613837af2ca2aac introduced the v14+
implementation of pg_encoding_verifymbstr(), it added a callback to each
pg_wchar_table entry.  For simplicity and ABI stability, this instead
implements the function in terms of the existing per-character callback.

Author: Noah Misch <[email protected]>
Author: Andres Freund <[email protected]>
Security: CVE-2025-1094

diff --git a/src/common/wchar.c b/src/common/wchar.c
index 0873480223628e8a979c89e441ea62bc3306a946..2d044ee4ffb0e9b9743daa2bf5459d497aaa3a00 100644 (file)
--- a/src/common/wchar.c
+++ b/src/common/wchar.c
@@ -1597,6 +1597,72 @@ pg_encoding_verifymb(int encoding, const char *mbstr, int len)
            pg_wchar_table[PG_SQL_ASCII].mbverify((const unsigned char *) mbstr, len));
 }
 
+/* v14+ function name, for easier backpatching */
+int
+pg_encoding_verifymbchar(int encoding, const char *mbstr, int len)
+{
+   int ok_bytes = pg_encoding_verifymb(encoding, mbstr, len);
+
+   if (ok_bytes == 0)
+       return -1;
+   return ok_bytes;
+}
+
+/* replace v14+ function, adapted from pg_verify_mbstr_len */
+int
+pg_encoding_verifymbstr(int encoding, const char *mbstr, int len)
+{
+   mbverifier  mbverify;
+   int         ok_bytes;
+
+   Assert(PG_VALID_ENCODING(encoding));
+
+   /*
+    * In single-byte encodings, we need only reject nulls (\0).
+    */
+   if (pg_encoding_max_length(encoding) <= 1)
+   {
+       const char *nullpos = memchr(mbstr, 0, len);
+
+       if (nullpos == NULL)
+           return len;
+       return nullpos - mbstr;
+   }
+
+   /* fetch function pointer just once */
+   mbverify = pg_wchar_table[encoding].mbverify;
+
+   ok_bytes = 0;
+
+   while (len > 0)
+   {
+       int         l;
+
+       /* fast path for ASCII-subset characters */
+       if (!IS_HIGHBIT_SET(*mbstr))
+       {
+           if (*mbstr != '\0')
+           {
+               ok_bytes++;
+               mbstr++;
+               len--;
+               continue;
+           }
+           return ok_bytes;
+       }
+
+       l = (*mbverify) ((const unsigned char *) mbstr, len);
+
+       if (l < 0)
+           return ok_bytes;
+
+       mbstr += l;
+       len -= l;
+       ok_bytes += l;
+   }
+   return ok_bytes;
+}
+
 /*
  * fetch maximum length of a given encoding
  */

diff --git a/src/include/mb/pg_wchar.h b/src/include/mb/pg_wchar.h
index b43454b64cea76a76c16cb344fef9845c0912eb1..b0dbde45b33b556a2f608937f41f3c266367d316 100644 (file)
--- a/src/include/mb/pg_wchar.h
+++ b/src/include/mb/pg_wchar.h
@@ -556,6 +556,8 @@ 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_verifymb(int encoding, const char *mbstr, int len);
+extern int pg_encoding_verifymbchar(int encoding, const char *mbstr, int len);
+extern int pg_encoding_verifymbstr(int encoding, const char *mbstr, int len);
 extern int pg_encoding_max_length(int encoding);
 extern int pg_valid_client_encoding(const char *name);
 extern int pg_valid_server_encoding(const char *name);