From 0feace3eb59bf10cfbb9657b2323f6dc0e82d748 Mon Sep 17 00:00:00 2001
From: Michael R Sweet <msweet@msweet.org>
Date: Sat, 10 Jan 2026 14:44:47 -0500
Subject: [PATCH] Fix AES-256 key initialization.

---
 CHANGES.md      | 1 +
 pdfio-aes.c     | 4 ++--
 pdfio-private.h | 4 ++--
 3 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/CHANGES.md b/CHANGES.md
index 79a4cf8..f4846a7 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -6,6 +6,7 @@ v1.7.0 - YYYY-MM-DD
 -------------------
 
 - Now use TTF 1.1 or later for font support.
+- Fixed a buffer overflow in the (still not enabled) AES-256 code.
 
 
 v1.6.2 - YYYY-MM-DD
diff --git a/pdfio-aes.c b/pdfio-aes.c
index 72f77ef..9f2ab4b 100644
--- a/pdfio-aes.c
+++ b/pdfio-aes.c
@@ -1,7 +1,7 @@
 //
 // AES functions for PDFio.
 //
-// Copyright © 2021-2025 by Michael R Sweet.
+// Copyright © 2021-2026 by Michael R Sweet.
 //
 // Licensed under Apache License v2.0.  See the file "LICENSE" for more
 // information.
@@ -117,7 +117,7 @@ _pdfioCryptoAESInit(
   memcpy(ctx->round_key, key, keylen);
 
   // All other round keys are found from the previous round keys.
-  for (rkptr0 = ctx->round_key, rkptr = rkptr0 + keylen, rkend = rkptr + 16 * ctx->round_size, i = nwords; rkptr < rkend; i ++)
+  for (rkptr0 = ctx->round_key, rkptr = rkptr0 + keylen, rkend = rkptr0 + 16 * ctx->round_size + 16, i = nwords; rkptr < rkend; i ++)
   {
     if ((i % nwords) == 0)
     {
diff --git a/pdfio-private.h b/pdfio-private.h
index e4d8f89..b84a8ac 100644
--- a/pdfio-private.h
+++ b/pdfio-private.h
@@ -1,7 +1,7 @@
 //
 // Private header file for PDFio.
 //
-// Copyright © 2021-2025 by Michael R Sweet.
+// Copyright © 2021-2026 by Michael R Sweet.
 //
 // Licensed under Apache License v2.0.  See the file "LICENSE" for more
 // information.
@@ -176,7 +176,7 @@ typedef struct _pdfio_value_s		// Value structure
 typedef struct _pdfio_aes_s		// AES encryption state
 {
   size_t	round_size;		// Size of round key
-  uint8_t	round_key[240],		// Round key
+  uint8_t	round_key[256],		// Round key
 		iv[16];			// Initialization vector
 } _pdfio_aes_t;