Prevent buffer overrun in read_tablespace_map().

Robert Foggia of Trustwave reported that read_tablespace_map()
fails to prevent an overrun of its on-stack input buffer.
Since the tablespace map file is presumed trustworthy, this does
not seem like an interesting security vulnerability, but still
we should fix it just in the name of robustness.

While here, document that pg_basebackup's --tablespace-mapping option
doesn't work with tar-format output, because it doesn't.  To make it
work, we'd have to modify the tablespace_map file within the tarball
sent by the server, which might be possible but I'm not volunteering.
(Less-painful solutions would require changing the basebackup protocol
so that the source server could adjust the map.  That's not very
appetizing either.)

diff --git a/doc/src/sgml/ref/pg_basebackup.sgml b/doc/src/sgml/ref/pg_basebackup.sgml
index f3d3badaaae4354930f2841b9e7abd8732447d0c..051ba241a9c7297bde0514467f842ba738754bfd 100644 (file)
--- a/doc/src/sgml/ref/pg_basebackup.sgml
+++ b/doc/src/sgml/ref/pg_basebackup.sgml
@@ -157,7 +157,8 @@ PostgreSQL documentation
             the target directory. If the cluster contains additional
             tablespaces, the main data directory will be placed in the
             target directory, but all other tablespaces will be placed
-            in the same absolute path as they have on the server.
+            in the same absolute path as they have on the source server.
+            (See <option>--tablespace-mapping</option> to change that.)
            </para>
            <para>
             This is the default format.
@@ -267,7 +268,12 @@ PostgreSQL documentation
         the main data directory are updated to point to the new location.  So
         the new data directory is ready to be used for a new server instance
         with all tablespaces in the updated locations.
-        </para>
+       </para>
+
+       <para>
+        Currently, this option only works with plain output format; it is
+        ignored if tar format is selected.
+       </para>
       </listitem>
      </varlistentry>
 

diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index fe0baf70da7adb7219f0174d8d274649b58b354a..9ad6da922c956a7bf9face3efa341bba4a43d4c6 100644 (file)
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -11179,7 +11179,7 @@ read_tablespace_map(List **tablespaces)
        }
        else if ((ch == '\n' || ch == '\r') && prev_ch == '\\')
            str[i - 1] = ch;
-       else
+       else if (i < sizeof(str) - 1)
            str[i++] = ch;
        prev_ch = ch;
    }