Real 80386 cpus have a special feature: they ignore the write-protected
bit in the page tables if the kernel runs at ring 0. This feature breaks
COW, the software must manually check the write protected bit before
writing.
Right now the check happens only in access_ok(VERIFY_WRITE).
This is broken, because:
- some codepaths call access_ok(VERIFY_READ), and then write.
- kswapd might change the page permissions between access_ok and the
actual write access.
-
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This archive was generated by hypermail 2b29 : Wed Apr 23 2003 - 22:00:30 EST