From fab649a1b9396ba37ae877ca8f1165754d407689 Mon Sep 17 00:00:00 2001
From: akallabeth <akallabeth@posteo.net>
Date: Fri, 19 Mar 2021 16:57:59 +0100
Subject: [PATCH] Fixed return length check for SCardGetAttrib

---
 channels/smartcard/client/smartcard_pack.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/channels/smartcard/client/smartcard_pack.c b/channels/smartcard/client/smartcard_pack.c
index d22ad74ab..68c983f85 100644
--- a/channels/smartcard/client/smartcard_pack.c
+++ b/channels/smartcard/client/smartcard_pack.c
@@ -2822,8 +2822,12 @@ LONG smartcard_pack_get_attrib_return(SMARTCARD_DEVICE* smartcard, wStream* s,
 		cbAttrLen = 0;
 	if (cbAttrLen == SCARD_AUTOALLOCATE)
 		cbAttrLen = 0;
-	if (cbAttrCallLen < cbAttrLen)
-		cbAttrLen = cbAttrCallLen;
+
+	if (ret->pbAttr)
+	{
+		if (cbAttrCallLen < cbAttrLen)
+			cbAttrLen = cbAttrCallLen;
+	}
 	Stream_Write_UINT32(s, cbAttrLen); /* cbAttrLen (4 bytes) */
 	if (!smartcard_ndr_pointer_write(s, &index, cbAttrLen))
 		return SCARD_E_NO_MEMORY;