From: Billie Alsup <balsup@cisco.com>
Date: Sat, 7 Dec 2024 07:42:38 +0000 (+0000)
Subject: DHCP: reduce buflen by 2 when creating a new RFC 3396 option
X-Git-Tag: v10.2.0~29
X-Git-Url: http://git.ipfire.org/gitweb/gitweb.cgi?a=commitdiff_plain;h=0f303ab474494b8ad4889d69df76309eba282efb;p=thirdparty%2Fdhcpcd.git

DHCP: reduce buflen by 2 when creating a new RFC 3396 option

Fixes #418 and potential buffer overflow.
---

diff --git a/src/dhcp.c b/src/dhcp.c
index 11c69bc1..9e23ab62 100644
--- a/src/dhcp.c
+++ b/src/dhcp.c
@@ -752,6 +752,7 @@ rfc3396_write(struct rfc3396_ctx *ctx, void *data, size_t len)
 			*(*ctx->buf)++ = ctx->code;
 			ctx->len = (*ctx->buf)++;
 			*ctx->len = 0;
+			ctx->buflen -= 2;
 			r += 2;
 		}