From: Kevin McCarthy <kevin@8t8.us>
Date: Thu, 14 Apr 2016 19:35:53 +0000 (-0700)
Subject: Fix right justify buffer-truncated pad calculation in mutt_FormatString()
X-Git-Tag: neomutt-20160822~171
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=b847879294e384b1442d5ff980a165d5e0faa746;p=neomutt

Fix right justify buffer-truncated pad calculation in mutt_FormatString()

Vincent Lefèvre noted that the computation had implementation defined
behavior and was potentially incorrect.

Change to make sure the subtraction won't lead to a wrap-around, and
set pad to 0 in that case.
---

diff --git a/muttlib.c b/muttlib.c
index 309f1bfed..fb485c7be 100644
--- a/muttlib.c
+++ b/muttlib.c
@@ -1297,7 +1297,7 @@ void mutt_FormatString (char *dest,		/* output buffer */
             /* try to consume as many columns as we can, if we don't have
              * memory for that, use as much memory as possible */
             if (wlen + (pad * pl) + len > destlen)
-              pad = ((signed)(destlen - wlen - len)) / pl;
+              pad = (destlen > wlen + len) ? ((destlen - wlen - len) / pl) : 0;
             else
             {
               /* Add pre-spacing to make multi-column pad characters and