CVE-2019-3824 ldb: wildcard_match end of data check

ldb_handler_copy and ldb_val_dup over allocate by one and add a trailing '\0'
to the data, to make them safe to use the C string functions on.

However testing for the trailing '\0' is not the correct way to test for
the end of a value, the length should be checked instead.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=13773

Signed-off-by: Gary Lockyer <gary@catalyst.net.nz>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>

diff --git a/lib/ldb/common/ldb_match.c b/lib/ldb/common/ldb_match.c
index 59f48b52b70449781f2073649e4bd616fa296cad..829afa77e716c33e5bfb932a242932595f4c050d 100644 (file)
--- a/lib/ldb/common/ldb_match.c
+++ b/lib/ldb/common/ldb_match.c
@@ -353,7 +353,7 @@ static int ldb_wildcard_compare(struct ldb_context *ldb,
        }
 
        /* last chunk may not have reached end of string */
-       if ( (! tree->u.substring.end_with_wildcard) && (*(val.data) != 0) ) goto mismatch;
+       if ( (! tree->u.substring.end_with_wildcard) && (val.length != 0) ) goto mismatch;
        talloc_free(save_p);
        *matched = true;
        return LDB_SUCCESS;