fix memory corruption using fix from

  https://github.com/ImageMagick/ImageMagick/pull/3858

1 files changed, 31 insertions, 0 deletions

diff --git a/3858.patch b/3858.patch
new file mode 100644
index 0000000..228c6d8
--- /dev/null
+++ b/3858.patch
@@ -0,0 +1,31 @@
+From f9ca2521de918c342618ee4dc0a01b70c92c024e Mon Sep 17 00:00:00 2001
+From: Remi Collet <remi@remirepo.net>
+Date: Wed, 23 Jun 2021 16:42:15 +0200
+Subject: [PATCH] fix memory corruption in ConcatenateStringInfo
+
+---
+ MagickCore/string.c | 4 ++--
+ 1 file changed, 2 insertions(+), 2 deletions(-)
+
+diff --git a/MagickCore/string.c b/MagickCore/string.c
+index dccef76a27..691d55034d 100644
+--- a/MagickCore/string.c
++++ b/MagickCore/string.c
+@@ -530,7 +530,6 @@ MagickExport void ConcatenateStringInfo(StringInfo *string_info,
+   length+=source->length;
+   if (~length < MagickPathExtent)
+     ThrowFatalException(ResourceLimitFatalError,"MemoryAllocationFailed");
+-  string_info->length=length;
+   if (string_info->datum == (unsigned char *) NULL)
+     string_info->datum=(unsigned char *) AcquireQuantumMemory(length+
+       MagickPathExtent,sizeof(*string_info->datum));
+@@ -540,7 +539,8 @@ MagickExport void ConcatenateStringInfo(StringInfo *string_info,
+       sizeof(*string_info->datum));
+   if (string_info->datum == (unsigned char *) NULL)
+     ThrowFatalException(ResourceLimitFatalError,"MemoryAllocationFailed");
+-  (void) memcpy(string_info->datum+length,source->datum,source->length);
++  (void) memcpy(string_info->datum+string_info->length,source->datum,source->length);
++  string_info->length=length;
+ }
+ 
+ /*