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    SubjectRe: Possible security hole? [was: verify_area(...) possible problem]
    Ralf Baechle wrote:
    > This is a known problem, it is pretty much similar to what happened
    > under 2.0 for all all architectures, not just the i386 and one of
    > reasons for the new user space access stuff introduced from 2.1.4 on.
    > Now that only the 386 is still affected just nobody bothered because
    > on the 386 there are other funnies left which may make running a
    > system used by possibly hostile users a bad idea.

    I haven't seen any security warnings against using a 386 for multiple
    users. Should there be one?

    Perhaps it would be possible to construct a patch which does this on a 386:

    - Implement read-write semaphores.
    - access_ok() grabs the mm semaphore, read-only, and sets a flag.
    - On exit from system call, if the flag is set it is cleared,
    and the mm read-only semaphore is released.
    - The page fault handler uses the read-only semaphore, otherwise

    -- Jamie

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      Last update: 2005-03-22 13:51    [W:0.063 / U:0.096 seconds]
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