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    SubjectRe: swapfile security weakeness
    On Thu, 5 Nov 1998, Brian Gerst wrote:

    >> 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...)
    >When you delete a file, you are just deleting the directory entry and
    >decrementing the inode usage count by 1. Only when the inode is used 0
    >time will the file actually be deleted from the filesystem. Opening the
    >file counts in the inode usage count as well, so as long as the swap
    >file is active, the file will still exist on the disk. Only when the
    >swap file is deactivated will the file be really deleted. Changing the
    >file's attributes may not work on all filesystems (like vfat/msdos, if
    >you're really desperate for swap space).

    My swap file was deleted while being used and instantly I got
    kernel panics. The file was located on an MSDOS volume.

    Mike A. Harris - Computer Consultant - Linux advocate

    Linux software galore:

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