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 ad282ceb5dd9eb640992d55c084099c7ac01fbeb..e2033b7e377d913f0f880a5d3cf770ca36bd4f13 100644 (file)
--- a/src/bin/pg_basebackup/streamutil.c
+++ b/src/bin/pg_basebackup/streamutil.c
@@ -309,7 +309,7 @@ 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 cb0f7f31fd7d26b87d2983b18f4a41351490574c..1e0aea4e25409139c2778fdd0bc3c550893fc773 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);