From 62d782156caddec0b4ca795d7236c6483d02efff Mon Sep 17 00:00:00 2001
From: Shivani Bhardwaj <shivani@oisf.net>
Date: Thu, 30 Mar 2023 13:13:08 +0530
Subject: [PATCH] util/base64: check dest buf size to hold 3Bytes

The destination buffer should be able to hold at least 3 Bytes during
the processing of the last block of data. If it cannot hold at least 3
Bytes, then that may lead to dynamic buffer overflow while decoding.
---
 src/util-base64.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/src/util-base64.c b/src/util-base64.c
index c9831ddca1..f2b4ba149d 100644
--- a/src/util-base64.c
+++ b/src/util-base64.c
@@ -165,6 +165,11 @@ Base64Ecode DecodeBase64(uint8_t *dest, uint32_t dest_size, const uint8_t *src,
             ecode = BASE64_ECODE_BUF;
             return ecode;
         }
+        /* if the destination size is not at least 3 Bytes long, it'll give a dynamic
+         * buffer overflow while decoding, so, return and let the caller take care of the
+         * remaining bytes to be decoded which should always be < 4 at this stage */
+        if (dest_size - *decoded_bytes < 3)
+            return BASE64_ECODE_BUF;
         *decoded_bytes += numDecoded_blk;
         DecodeBase64Block(dptr, b64);
         *consumed_bytes += bbidx;