Fix sscanf limits in pg_basebackup and pg_dump

Make sure that the string parsing is limited by the size of the
destination buffer.

In pg_basebackup the available values sent from the server
is limited to two characters so there was no risk of overflow.

In pg_dump the buffer is bounded by MAXPGPATH, and thus the limit
must be inserted via preprocessor expansion and the buffer increased
by one to account for the terminator. There is no risk of overflow
here, since in this case, the buffer scanned is smaller than the
destination buffer.

Backpatch the pg_basebackup fix to 11 where it was introduced, and
the pg_dump fix all the way down to 9.6.

Reviewed-by: Tom Lane
Discussion: https://postgr.es/m/B14D3D7B-F98C-4E20-9459-C122C67647FB@yesql.se
Backpatch-through: 11 and 9.6

diff --git a/src/bin/pg_basebackup/streamutil.c b/src/bin/pg_basebackup/streamutil.c
index 37237cd5d95c946cbebc54db240db07025ffaa60..a9bc1ce2149363c687f881e711d84b6dbd8218d7 100644 (file)
--- a/src/bin/pg_basebackup/streamutil.c
+++ b/src/bin/pg_basebackup/streamutil.c
@@ -310,7 +310,7 @@ RetrieveWalSegSize(PGconn *conn)
    }
 
    /* fetch xlog value and unit from the result */
-   if (sscanf(PQgetvalue(res, 0, 0), "%d%s", &xlog_val, xlog_unit) != 2)
+   if (sscanf(PQgetvalue(res, 0, 0), "%d%2s", &xlog_val, xlog_unit) != 2)
    {
        pg_log_error("WAL segment size could not be parsed");
        PQclear(res);

diff --git a/src/bin/pg_dump/pg_backup_directory.c b/src/bin/pg_dump/pg_backup_directory.c
index fb8c7713a508a943a8b5d1858f7faed97e964db4..57243c5971cbd455d70e8352c6bd882ed02576e1 100644 (file)
--- a/src/bin/pg_dump/pg_backup_directory.c
+++ b/src/bin/pg_dump/pg_backup_directory.c
@@ -449,11 +449,11 @@ _LoadBlobs(ArchiveHandle *AH)
    /* Read the blobs TOC file line-by-line, and process each blob */
    while ((cfgets(ctx->blobsTocFH, line, MAXPGPATH)) != NULL)
    {
-       char        fname[MAXPGPATH];
+       char        fname[MAXPGPATH + 1];
        char        path[MAXPGPATH];
 
        /* Can't overflow because line and fname are the same length. */
-       if (sscanf(line, "%u %s\n", &oid, fname) != 2)
+       if (sscanf(line, "%u %" CppAsString2(MAXPGPATH) "s\n", &oid, fname) != 2)
            fatal("invalid line in large object TOC file \"%s\": \"%s\"",
                  fname, line);