From 1251312a101f9fe18de9ece6961c9ea7e95a3dfc Mon Sep 17 00:00:00 2001
From: Kamil Kasperczyk <66371704+kkasperczyk-no@users.noreply.github.com>
Date: Thu, 19 May 2022 16:55:03 +0200
Subject: [PATCH] [setup_payload] Fixed bug with not reducing span size
 properly (#18598)

Output buffer span is not reduced properly, as subspan is
passed to the base38Encode method and changed size doesn't
propagate to the outBuffer.

Added reducing outBuffer size to the subSpan + prefixLen size.
---
 src/setup_payload/QRCodeSetupPayloadGenerator.cpp | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/setup_payload/QRCodeSetupPayloadGenerator.cpp b/src/setup_payload/QRCodeSetupPayloadGenerator.cpp
index c8e7dc7fc1b2ad..976e443afa2c89 100644
--- a/src/setup_payload/QRCodeSetupPayloadGenerator.cpp
+++ b/src/setup_payload/QRCodeSetupPayloadGenerator.cpp
@@ -196,6 +196,8 @@ static CHIP_ERROR payloadBase38RepresentationWithTLV(PayloadContents & payload,
         MutableCharSpan subSpan = outBuffer.SubSpan(prefixLen, outBuffer.size() - prefixLen);
         memcpy(outBuffer.data(), kQRCodePrefix, prefixLen);
         err = base38Encode(bits, subSpan);
+        // Reduce output span size to be the size of written data
+        outBuffer.reduce_size(subSpan.size() + prefixLen);
     }
 
     return err;