From: Manfred Spraul <manfred@colorfullife.com>
To: linux-kernel@vger.kernel.org
Subject: [RFC, PATCH] fix verify_write for 80386 support
Date: Mon, 21 Apr 2003 22:28:53 +0200 [thread overview]
Message-ID: <3EA45485.2080500@colorfullife.com> (raw)
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.
next reply other threads:[~2003-04-21 20:16 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-04-21 20:28 Manfred Spraul [this message]
2003-04-21 20:36 ` [RFC, PATCH] fix verify_write for 80386 support Manfred Spraul
2003-04-22 2:13 ` Brian Gerst
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