From 04107e98d58efb69f7e2d7b81176e5374c7098a3 Mon Sep 17 00:00:00 2001
From: Jeremy Harris <jgh146exb@wizmail.org>
Date: Thu, 11 May 2023 21:08:08 +0100
Subject: [PATCH] Auths: fix possible OOB read in SPA authenticator.  Bug 3001

---
 doc/doc-txt/ChangeLog    |  3 +++
 src/src/auths/auth-spa.c | 36 ++++++++++++++++++++++++++++--------
 2 files changed, 31 insertions(+), 8 deletions(-)

diff --git a/doc/doc-txt/ChangeLog b/doc/doc-txt/ChangeLog
index 95377514f..406c4b0c4 100644
--- a/doc/doc-txt/ChangeLog
+++ b/doc/doc-txt/ChangeLog
@@ -199,6 +199,9 @@ JH/40 Bug 2999: Fix a possible OOB write in the external authenticator, which
 JH/41 Bug 3000: Fix a possible OOB write in the SPA authenticator, which could
       be triggered by externally-controlled input.  Found by Trend Micro.
 
+JH/42 Bug 3001: Fix a possible OOB read in the SPA authenticator, which could
+      be triggered by externally-controlled input.  Found by Trend Micro.
+
 
 Exim version 4.96
 -----------------
diff --git a/src/src/auths/auth-spa.c b/src/src/auths/auth-spa.c
index d7a12aa23..8e3146b35 100644
--- a/src/src/auths/auth-spa.c
+++ b/src/src/auths/auth-spa.c
@@ -1255,15 +1255,10 @@ spa_bytes_add(ptr, header, b, len*2); \
 }
 
 
-#define GetUnicodeString(structPtr, header) \
-unicodeToString(((char*)structPtr) + IVAL(&structPtr->header.offset,0) , SVAL(&structPtr->header.len,0)/2)
-#define GetString(structPtr, header) \
-toString(((CS structPtr) + IVAL(&structPtr->header.offset,0)), SVAL(&structPtr->header.len,0))
-
 #ifdef notdef
 
 #define DumpBuffer(fp, structPtr, header) \
-dumpRaw(fp,(US structPtr)+IVAL(&structPtr->header.offset,0),SVAL(&structPtr->header.len,0))
+ dumpRaw(fp,(US structPtr)+IVAL(&structPtr->header.offset,0),SVAL(&structPtr->header.len,0))
 
 
 static void
@@ -1327,8 +1322,33 @@ buf[len] = 0;
 return buf;
 }
 
+static inline uschar *
+get_challenge_unistr(SPAAuthChallenge * challenge, SPAStrHeader * hdr)
+{
+int off = IVAL(&hdr->offset, 0);
+int len = SVAL(&hdr->len, 0);
+return off + len < sizeof(SPAAuthChallenge)
+  ? US unicodeToString(CS challenge + off, len/2) : US"";
+}
+
+static inline uschar *
+get_challenge_str(SPAAuthChallenge * challenge, SPAStrHeader * hdr)
+{
+int off = IVAL(&hdr->offset, 0);
+int len = SVAL(&hdr->len, 0);
+return off + len < sizeof(SPAAuthChallenge)
+  ? US toString(CS challenge + off, len) : US"";
+}
+
 #ifdef notdef
 
+#define GetUnicodeString(structPtr, header) \
+ unicodeToString(((char*)structPtr) + IVAL(&structPtr->header.offset,0) , SVAL(&structPtr->header.len,0)/2)
+
+#define GetString(structPtr, header) \
+ toString(((CS structPtr) + IVAL(&structPtr->header.offset,0)), SVAL(&structPtr->header.len,0))
+
+
 void
 dumpSmbNtlmAuthRequest (FILE * fp, SPAAuthRequest * request)
 {
@@ -1498,8 +1518,8 @@ if (p)
   }
 
 else domain = d = string_copy(cf & 0x1
-  ? CUS GetUnicodeString(challenge, uDomain)
-  : CUS GetString(challenge, uDomain));
+  ? CUS get_challenge_unistr(challenge, &challenge->uDomain)
+  : CUS get_challenge_str(challenge, &challenge->uDomain));
 
 spa_smb_encrypt(password, challenge->challengeData, lmRespData);
 spa_smb_nt_encrypt(password, challenge->challengeData, ntRespData);
-- 
2.30.2