Re: How to read-protect a vm_area?

Alan Cox (alan@lxorguk.ukuu.org.uk)
Mon, 16 Feb 1998 20:25:14 +0000 (GMT)

> Note that this is an issue only for something that _has_ been accessible
> and then has turned into PROT_NONE by using mprotect() - because if the
> pages aren't there at all then the page fault handler will refuse to page
> them in even when the access is done from kernel space.

As is done by Texas, Electric Fence ... It potentially stops ElectricFence
detecting a syscall into an area that has been read/written to after being
freed, and I think it means anyone wanting to run the texas persistent object
store needs to go and download OpenBSD.

How tricky is it to handle - I agree its not a normal issue..

Alan

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