From: "Reese Faucette" <reesefaucette@gmail.com>
To: <linux-kernel@vger.kernel.org>
Cc: <alan@lxorguk.ukuu.org.uk>
Subject: [PATCH] overflow check calculation in mm/mmap.c is incorrect linux-3.12.38
Date: Wed, 29 Apr 2015 22:14:19 -0700 [thread overview]
Message-ID: <007301d08304$85881420$90983c60$@gmail.com> (raw)
When checking for overflow, the code in mm/mmap.c compares the first byte
*after* the end of mapped region to the start of the region instead of the
last byte of the mapped region. This prevents mapping a region which abuts
the end of physical space, as mmap() incorrectly rejects the region with
-EOVERFLOW, because pgoff + (len >> PAGE_SHIFT) will be 0, which is < pgoff.
-reese
Reese Faucette
Cisco Systems, Inc.
====================================================
--- mm/mmap.c
+++ mm/mmap.c
@@ -1241,7 +1241,7 @@
return -ENOMEM;
/* offset overflow? */
- if ((pgoff + (len >> PAGE_SHIFT)) < pgoff)
+ if ((pgoff + (len >> PAGE_SHIFT) - 1) < pgoff)
return -EOVERFLOW;
/* Too many mappings? */
next reply other threads:[~2015-04-30 5:14 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-04-30 5:14 Reese Faucette [this message]
2015-05-07 23:53 ` [PATCH] overflow check calculation in mm/mmap.c is incorrect linux-3.12.38 Andrew Morton
2015-05-08 9:46 ` Rasmus Villemoes
2015-05-13 16:58 ` Reese Faucette
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