Messages in this thread |  | | | Date | Mon, 19 Apr 1999 20:09:12 +0200 | | From | Jamie Lokier <> | | Subject | Re: Possible security hole? [was: verify_area(...) possible problem] |
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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 deadlock.
-- Jamie
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