From 0a6047eef1c465c38aacfbdab193161b3f0cd144 Mon Sep 17 00:00:00 2001
From: Linus Torvalds <torvalds@g5.osdl.org>
Date: Wed, 28 Jun 2006 17:09:34 -0700
Subject: [PATCH] Fix vsnprintf off-by-one bug

The recent vsnprintf() fix introduced an off-by-one, and it's now
possible to overrun the target buffer by one byte.

The "end" pointer points to past the end of the buffer, so if we
have to truncate the result, it needs to be done though "end[-1]".

[ This is just an alternate and simpler patch to one proposed by Andrew
  and Jeremy, who actually noticed the problem ]

Acked-by: Andrew Morton <akpm@osdl.org>
Acked-by: Jeremy Fitzhardinge <jeremy@goop.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
---
 lib/vsprintf.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index 797428afd1114..bed7229378f2d 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -489,7 +489,7 @@ int vsnprintf(char *buf, size_t size, const char *fmt, va_list args)
 		if (str < end)
 			*str = '\0';
 		else
-			*end = '\0';
+			end[-1] = '\0';
 	}
 	/* the trailing null byte doesn't count towards the total */
 	return str-buf;
-- 
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