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    SubjectRe: swapfile security weakeness

    On Thu, 5 Nov 1998 20:39:18 +0100 (CET), Jakub Vlasek <>

    > i've found that active swapfile could be deleted, which is
    > IMHO very dangerous (set immutable flag on in sys_swapon call?). Also,
    > sys_swapon should check whether owner of swapfile is root and is readable
    > only to root ( memory readableby anyone? hmm...)

    2.0 or 2.1? I've just tried on 2.1.127 and it is working fine: the file
    is unlinked but not deleted and the filesystem space remains reserved.

    On Fri, 6 Nov 1998 08:40:01 +0100 (CET), Rik van Riel
    <> said:

    > Unfortunately, there are a few issues with that:
    > - it doesn't work on inodeless FSes (msdosfs)

    Not true. All filesystems have inodes.

    > - you can't swapoff() a deleted file, leaving minor
    > fs corruption on reboot (and major corruption on
    > umsdos and the like)

    That's no different to the normal case of rebooting with a file still
    open. At least on ext2, the filesystem will automatically be re-fscked
    on boot.

    > - since you can't swapoff() the deleted file, you
    > can't reclaim the disk space

    The fsck will fix things up.


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