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Message-Id: <1420719287-10222-3-git-send-email-linux@rasmusvillemoes.dk>
Date: Thu, 8 Jan 2015 13:14:46 +0100
From: Rasmus Villemoes <linux@...musvillemoes.dk>
To: Andrew Morton <akpm@...ux-foundation.org>,
Jiri Kosina <jkosina@...e.cz>,
Randy Dunlap <rdunlap@...radead.org>
Cc: Rasmus Villemoes <linux@...musvillemoes.dk>,
linux-kernel@...r.kernel.org
Subject: [PATCH 3/4] lib/vsprintf.c: Don't try to fix pointer wrap-around
Actual kernel buffers can't wrap into the user address space. If
someone manages to pass a buf/size combination that wraps, it is most
likely due to a bug in the caller. Instead of trying to fix it by
using a smaller part of the buffer, bail out.
Signed-off-by: Rasmus Villemoes <linux@...musvillemoes.dk>
---
lib/vsprintf.c | 8 +++-----
1 file changed, 3 insertions(+), 5 deletions(-)
diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index cf12ba86205c..1ec6a78f169b 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -1733,11 +1733,9 @@ int vsnprintf(char *buf, size_t size, const char *fmt, va_list args)
str = buf;
end = buf + size;
- /* Make sure end is always >= buf */
- if (end < buf) {
- end = ((void *)-1);
- size = end - buf;
- }
+ /* Also bail out if buf+size wraps */
+ if (WARN_ON_ONCE(end < buf))
+ return 0;
while (*fmt) {
const char *old_fmt = fmt;
--
2.1.3
--
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