lkml.org 
[lkml]   [2018]   [Mar]   [19]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH 4.4 131/134] btrfs: Fix use-after-free when cleaning up fs_devs with a single stale device
    Date
    4.4-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Nikolay Borisov <nborisov@suse.com>

    commit fd649f10c3d21ee9d7542c609f29978bdf73ab94 upstream.

    Commit 4fde46f0cc71 ("Btrfs: free the stale device") introduced
    btrfs_free_stale_device which iterates the device lists for all
    registered btrfs filesystems and deletes those devices which aren't
    mounted. In a btrfs_devices structure has only 1 device attached to it
    and it is unused then btrfs_free_stale_devices will proceed to also free
    the btrfs_fs_devices struct itself. Currently this leads to a use after
    free since list_for_each_entry will try to perform a check on the
    already freed memory to see if it has to terminate the loop.

    The fix is to use 'break' when we know we are freeing the current
    fs_devs.

    Fixes: 4fde46f0cc71 ("Btrfs: free the stale device")
    Signed-off-by: Nikolay Borisov <nborisov@suse.com>
    Reviewed-by: Anand Jain <anand.jain@oracle.com>
    Signed-off-by: David Sterba <dsterba@suse.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    fs/btrfs/volumes.c | 1 +
    1 file changed, 1 insertion(+)

    --- a/fs/btrfs/volumes.c
    +++ b/fs/btrfs/volumes.c
    @@ -568,6 +568,7 @@ void btrfs_free_stale_device(struct btrf
    btrfs_sysfs_remove_fsid(fs_devs);
    list_del(&fs_devs->list);
    free_fs_devices(fs_devs);
    + break;
    } else {
    fs_devs->num_devices--;
    list_del(&dev->dev_list);

    \
     
     \ /
      Last update: 2018-03-19 21:06    [W:4.252 / U:0.180 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site