From c17b535a33f9388e7eb183c3e1a0971259f4a5e6 Mon Sep 17 00:00:00 2001
From: Lukas Fleischer <calcurse@cryptocrack.de>
Date: Sat, 18 Feb 2012 15:40:01 +0100
Subject: Fix up strncat() usage

The last argument to strncat() should not be the total buffer length; it
should be the space remaining:

    The strncat() function shall append not more than n bytes (a null
    byte and bytes that follow it are not appended) from the array
    pointed to by s2 to the end of the string pointed to by s1. The
    initial byte of s2 overwrites the null byte at the end of s1. A
    terminating null byte is always appended to the result.

This patch fixes a couple of potential buffer overflow vulnerabilities.

Signed-off-by: Lukas Fleischer <calcurse@cryptocrack.de>
---
 src/config.c | 4 ++--
 src/ical.c   | 3 +--
 src/keys.c   | 4 ++--
 src/note.c   | 4 ++--
 4 files changed, 7 insertions(+), 8 deletions(-)

diff --git a/src/config.c b/src/config.c
index 9bdb201..e965c1a 100644
--- a/src/config.c
+++ b/src/config.c
@@ -562,10 +562,10 @@ config_save (void)
   int i;
 
   strncpy (tmppath, get_tempdir (), BUFSIZ);
-  strncat (tmppath, "/" CONF_PATH_NAME ".", BUFSIZ);
+  strncat (tmppath, "/" CONF_PATH_NAME ".", BUFSIZ - strlen (tmppath) - 1);
   if ((tmpext = new_tempfile (tmppath, TMPEXTSIZ)) == NULL)
     return 0;
-  strncat (tmppath, tmpext, BUFSIZ);
+  strncat (tmppath, tmpext, BUFSIZ - strlen (tmppath) - 1);
   mem_free (tmpext);
 
   status.fp = fopen (tmppath, "w");
diff --git a/src/ical.c b/src/ical.c
index 4360a76..ac158fc 100644
--- a/src/ical.c
+++ b/src/ical.c
@@ -447,8 +447,7 @@ ical_readline (FILE *fdi, char *buf, char *lstore, unsigned *ln)
         *eol = '\0';
       if (*lstore != SPACE && *lstore != TAB)
         break;
-      strncat (buf, lstore + 1, BUFSIZ);
-      buf[BUFSIZ - 1] = '\0';
+      strncat (buf, lstore + 1, BUFSIZ - strlen (buf) - 1);
       (*ln)++;
     }
 
diff --git a/src/keys.c b/src/keys.c
index 005595d..dc0d95f 100644
--- a/src/keys.c
+++ b/src/keys.c
@@ -436,7 +436,7 @@ keys_format_label (char *key, int keylen)
 {
   static char fmtkey[BUFSIZ];
   const int len = strlen (key);
-  char *dot = ".";
+  const char dot = '.';
   int i;
 
   if (keylen > BUFSIZ)
@@ -455,7 +455,7 @@ keys_format_label (char *key, int keylen)
     {
       for (i = 0; i < keylen - 1; i++)
         fmtkey[i] = key[i];
-      strncat (fmtkey, dot, strlen (dot));
+      fmtkey[keylen - 1] = dot;
     }
   return fmtkey;
 }
diff --git a/src/note.c b/src/note.c
index 2686dd7..1891a5f 100644
--- a/src/note.c
+++ b/src/note.c
@@ -76,10 +76,10 @@ edit_note (char **note, char *editor)
   FILE *fp;
 
   strncpy (tmppath, get_tempdir (), BUFSIZ);
-  strncat (tmppath, "/calcurse-note.", BUFSIZ);
+  strncat (tmppath, "/calcurse-note.", BUFSIZ - strlen (tmppath) - 1);
   if ((tmpext = new_tempfile (tmppath, TMPEXTSIZ)) == NULL)
     return;
-  strncat (tmppath, tmpext, BUFSIZ);
+  strncat (tmppath, tmpext, BUFSIZ - strlen (tmppath) - 1);
   mem_free (tmpext);
 
   if (*note != NULL)
-- 
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