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 e6b062f316d851b591f75e0f86833b9e855b893d..ca5ee3fcebbed0886e69ff7270cd2ec6ee988ae6 100644 (file)
--- a/src/bin/pg_basebackup/streamutil.c
+++ b/src/bin/pg_basebackup/streamutil.c
@@ -311,7 +311,7 @@ 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 ffea0f7fd73e403dd6ebc5d899017a310cc7440e..853692dc27f582e83afb2eff13c2d868e51a0890 100644 (file)
--- a/src/bin/pg_dump/pg_backup_directory.c
+++ b/src/bin/pg_dump/pg_backup_directory.c
@@ -451,11 +451,11 @@ _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);