From: Chen Gang <gang.chen@asianux.com>
Date: Fri, 7 Jun 2013 00:07:53 +0000 (+1000)
Subject: mm/nommu.c: add additional check for vread() just like vwrite() has done
X-Git-Tag: next-20130607~2^2~401
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=20de3cf0c143a6dbcc77b0ee97d5edfc99143139;p=karo-tx-linux.git

mm/nommu.c: add additional check for vread() just like vwrite() has done

vwrite() checks for overflow. vread() should do the same thing.

Since vwrite() checks the source buffer address, vread() should check
the destination buffer address.

Signed-off-by: Chen Gang <gang.chen@asianux.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Michel Lespinasse <walken@google.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

diff --git a/mm/nommu.c b/mm/nommu.c
index 886e07ce4d1d..0614ee1eeb66 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -282,6 +282,10 @@ EXPORT_SYMBOL(vmalloc_to_pfn);
 
 long vread(char *buf, char *addr, unsigned long count)
 {
+	/* Don't allow overflow */
+	if ((unsigned long) buf + count < count)
+		count = -(unsigned long) buf;
+
 	memcpy(buf, addr, count);
 	return count;
 }