linux-kernel - [patch] xfs: check for underflow in xfs_iformat

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Message-ID: <20130815055338.GC23580@elgon.mountain>
Date:	Thu, 15 Aug 2013 08:53:38 +0300
From:	Dan Carpenter <dan.carpenter@...cle.com>
To:	Ben Myers <bpm@....com>
Cc:	Alex Elder <elder@...nel.org>, xfs@....sgi.com,
	linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org
Subject: [patch] xfs: check for underflow in xfs_iformat_fork()

The "di_size" variable comes from the disk and it's a signed 64 bit.
We check the upper limit but we should check for negative numbers as
well.

Signed-off-by: Dan Carpenter <dan.carpenter@...cle.com>

diff --git a/fs/xfs/xfs_inode_fork.c b/fs/xfs/xfs_inode_fork.c
index 123971b..849fc70 100644
--- a/fs/xfs/xfs_inode_fork.c
+++ b/fs/xfs/xfs_inode_fork.c
@@ -167,7 +167,8 @@ xfs_iformat_fork(
 			}
 
 			di_size = be64_to_cpu(dip->di_size);
-			if (unlikely(di_size > XFS_DFORK_DSIZE(dip, ip->i_mount))) {
+			if (unlikely(di_size < 0 ||
+				     di_size > XFS_DFORK_DSIZE(dip, ip->i_mount))) {
 				xfs_warn(ip->i_mount,
 			"corrupt inode %Lu (bad size %Ld for local inode).",
 					(unsigned long long) ip->i_ino,
--
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