From: Volker Lendecke <vl@samba.org>
Date: Tue, 21 Jul 2026 09:06:53 +0000 (+0200)
Subject: lib: Check there's data remaining before calculating how much
X-Git-Tag: samba-4.25.0rc1~87
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=be2372888c5cbce0d363a64678a7fe0d0e286447;p=thirdparty%2Fsamba.git

lib: Check there's data remaining before calculating how much

Better make sure the subtraction does not go negative before we do it.

Signed-off-by: Volker Lendecke <vl@samba.org>
Reviewed-by: Anoop C S <anoopcs@samba.org>
---

diff --git a/lib/util/asn1.c b/lib/util/asn1.c
index 3cf872d3bf2..ab9820b26c5 100644
--- a/lib/util/asn1.c
+++ b/lib/util/asn1.c
@@ -760,11 +760,12 @@ int asn1_tag_remaining(struct asn1_data *data)
 	}
 	consumed = data->ofs - data->nesting->start;
 
-	remaining = data->nesting->taglen - consumed;
-	if (remaining > (data->length - data->ofs)) {
+	if (data->nesting->taglen < consumed) {
 		goto error;
 	}
-	if (remaining < 0) {
+	remaining = data->nesting->taglen - consumed;
+
+	if (remaining > (data->length - data->ofs)) {
 		goto error;
 	}
 	return remaining;