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Message-ID: <C1E3B80C-FF09-4611-A6BE-6A0576987F5B@redhat.com>
Date: Thu, 21 Jul 2016 08:30:52 -0400
From: "Benjamin Coddington" <bcodding@...hat.com>
To: "Artem Savkov" <asavkov@...hat.com>
Cc: "Christoph Hellwig" <hch@....de>,
"Anna Schumaker" <Anna.Schumaker@...app.com>,
linux-nfs@...r.kernel.org, linux-kernel@...r.kernel.org,
trond.myklebust@...marydata.com
Subject: Re: [PATCH v3] Fix NULL pointer dereference in bl_free_device().
On 21 Jul 2016, at 7:32, Artem Savkov wrote:
> When bl_parse_deviceid() fails in bl_alloc_deviceid_node() on
> blkdev_get_by_*() step we get an pnfs_block_dev struct that is
> uninitialized except for bdev field which is set to whatever error
> blkdev_get_by_*() returns. bl_free_device() then tries to call
> blkdev_put() if bdev is not 0 resulting in a wrong pointer
> dereference.
>
> Fixing this by setting bdev in struct pnfs_block_dev only if we didn't
> get an error from blkdev_get_by_*().
>
> Signed-off-by: Artem Savkov <asavkov@...hat.com>
Looks good to me.
Reviewed-by: Benjamin Coddington <bcodding@...hat.com>
> ---
> fs/nfs/blocklayout/dev.c | 22 +++++++++++++---------
> 1 file changed, 13 insertions(+), 9 deletions(-)
>
> diff --git a/fs/nfs/blocklayout/dev.c b/fs/nfs/blocklayout/dev.c
> index 118252f..a69ef4e 100644
> --- a/fs/nfs/blocklayout/dev.c
> +++ b/fs/nfs/blocklayout/dev.c
> @@ -235,18 +235,20 @@ bl_parse_simple(struct nfs_server *server,
> struct pnfs_block_dev *d,
> struct pnfs_block_volume *volumes, int idx, gfp_t gfp_mask)
> {
> struct pnfs_block_volume *v = &volumes[idx];
> + struct block_device *bdev;
> dev_t dev;
>
> dev = bl_resolve_deviceid(server, v, gfp_mask);
> if (!dev)
> return -EIO;
>
> - d->bdev = blkdev_get_by_dev(dev, FMODE_READ | FMODE_WRITE, NULL);
> - if (IS_ERR(d->bdev)) {
> + bdev = blkdev_get_by_dev(dev, FMODE_READ | FMODE_WRITE, NULL);
> + if (IS_ERR(bdev)) {
> printk(KERN_WARNING "pNFS: failed to open device %d:%d (%ld)\n",
> - MAJOR(dev), MINOR(dev), PTR_ERR(d->bdev));
> - return PTR_ERR(d->bdev);
> + MAJOR(dev), MINOR(dev), PTR_ERR(bdev));
> + return PTR_ERR(bdev);
> }
> + d->bdev = bdev;
>
>
> d->len = i_size_read(d->bdev->bd_inode);
> @@ -350,17 +352,19 @@ bl_parse_scsi(struct nfs_server *server, struct
> pnfs_block_dev *d,
> struct pnfs_block_volume *volumes, int idx, gfp_t gfp_mask)
> {
> struct pnfs_block_volume *v = &volumes[idx];
> + struct block_device *bdev;
> const struct pr_ops *ops;
> int error;
>
> if (!bl_validate_designator(v))
> return -EINVAL;
>
> - d->bdev = bl_open_dm_mpath_udev_path(v);
> - if (IS_ERR(d->bdev))
> - d->bdev = bl_open_udev_path(v);
> - if (IS_ERR(d->bdev))
> - return PTR_ERR(d->bdev);
> + bdev = bl_open_dm_mpath_udev_path(v);
> + if (IS_ERR(bdev))
> + bdev = bl_open_udev_path(v);
> + if (IS_ERR(bdev))
> + return PTR_ERR(bdev);
> + d->bdev = bdev;
>
> d->len = i_size_read(d->bdev->bd_inode);
> d->map = bl_map_simple;
> --
> 2.5.5
>
> --
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