linux-kernel - [PATCH -mm 3/7][AIO] - Fix access

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Message-ID: <20070201103011.69ebafc8@frecb000686>
Date:	Thu, 1 Feb 2007 10:30:11 +0100
From:	Sébastien Dugué <sebastien.dugue@...l.net>
To:	linux-kernel <linux-kernel@...r.kernel.org>
Cc:	Andrew Morton <akpm@...l.org>, linux-aio <linux-aio@...ck.org>,
	Bharata B Rao <bharata@...ibm.com>,
	Christoph Hellwig <hch@...radead.org>,
	Suparna Bhattacharya <suparna@...ibm.com>,
	Ulrich Drepper <drepper@...hat.com>,
	Zach Brown <zach.brown@...cle.com>,
	Oleg Nesterov <oleg@...sign.ru>,
	Badari Pulavarty <pbadari@...ibm.com>,
	Benjamin LaHaise <bcrl@...ux.intel.com>,
	Jean Pierre Dion <jean-pierre.dion@...l.net>
Subject: [PATCH -mm 3/7][AIO] - Fix access_ok() checks


From: Sébastien Dugué <sebastien.dugue@...l.net>

                   Fix access_ok() checks in sys_io_submit() and 
                            compat_sys_io_submit()


  sys_io_submit() and compat_sys_io_submit() check for the number of
requests (nr) being positive, but the following access_ok() call uses
nr * sizeof(ptr) which can overlow to a negative number.

  Just make sure that nr * sizeof(ptr) is positive in the first place.


 aio.c    |    2 +-
 compat.c |    2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

Signed-off-by: Sébastien Dugué <sebastien.dugue@...l.net>

Index: linux-2.6.20-rc6-mm3/fs/aio.c
===================================================================
--- linux-2.6.20-rc6-mm3.orig/fs/aio.c	2007-01-30 11:28:56.000000000 +0100
+++ linux-2.6.20-rc6-mm3/fs/aio.c	2007-01-30 11:32:42.000000000 +0100
@@ -1630,7 +1630,7 @@ asmlinkage long sys_io_submit(aio_contex
 	long ret = 0;
 	int i;
 
-	if (unlikely(nr < 0))
+	if (unlikely((nr*sizeof(*iocbpp)) < 0))
 		return -EINVAL;
 
 	if (unlikely(!access_ok(VERIFY_READ, iocbpp, (nr*sizeof(*iocbpp)))))
Index: linux-2.6.20-rc6-mm3/fs/compat.c
===================================================================
--- linux-2.6.20-rc6-mm3.orig/fs/compat.c	2007-01-30 11:30:29.000000000 +0100
+++ linux-2.6.20-rc6-mm3/fs/compat.c	2007-01-30 11:31:55.000000000 +0100
@@ -651,7 +651,7 @@ compat_sys_io_submit(aio_context_t ctx_i
 	long ret = 0;
 	int i;
 
-	if (unlikely(nr < 0))
+	if (unlikely((nr * sizeof(u32)) < 0))
 		return -EINVAL;
 
 	if (unlikely(!access_ok(VERIFY_READ, iocb, (nr * sizeof(u32)))))
-
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