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Message-ID: <20160128213858.GA29114@infradead.org>
Date: Thu, 28 Jan 2016 13:38:58 -0800
From: Christoph Hellwig <hch@...radead.org>
To: Ross Zwisler <ross.zwisler@...ux.intel.com>
Cc: linux-kernel@...r.kernel.org,
Alexander Viro <viro@...iv.linux.org.uk>,
Andrew Morton <akpm@...ux-foundation.org>,
Dan Williams <dan.j.williams@...el.com>,
Dave Chinner <david@...morbit.com>, Jan Kara <jack@...e.com>,
Matthew Wilcox <willy@...ux.intel.com>,
linux-fsdevel@...r.kernel.org, linux-nvdimm@...1.01.org
Subject: Re: [PATCH 2/2] dax: fix bdev NULL pointer dereferences
On Thu, Jan 28, 2016 at 12:35:04PM -0700, Ross Zwisler wrote:
> There are a number of places in dax.c that look up the struct block_device
> associated with an inode. Previously this was done by just using
> inode->i_sb->s_bdev. This is correct for inodes that exist within the
> filesystems supported by DAX (ext2, ext4 & XFS), but when running DAX
> against raw block devices this value is NULL. This causes NULL pointer
> dereferences when these block_device pointers are used.
It's also wrong for an XFS file system with a RT device..
> +#define DAX_BDEV(inode) (S_ISBLK(inode->i_mode) ? I_BDEV(inode) \
> + : inode->i_sb->s_bdev)
.. but this isn't going to fix it. You must use a bdev returned by
get_blocks or a similar file system method.
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