Re: PATCH - bug in vfree

Andrea Arcangeli
1999-02-25T01:01:11Z

On Sat, 20 Feb 1999, Neil Booth wrote:

>I posted this bug on the kernel mailing list last year, but it never got
>fixed, probably as I didn't include a patch. I attach a patch this time

I included it one year ago in my tree and infact if you grab my
arca-patches you'll find it again ;).

>against kernel 2.2.1. The bug is rare, but can lead to kernel virtual
>memory corruption.

Hmm, when I checked it one year ago I didn't seen a way the bug could
corrupt memory.

>More deeply:- Close inspection of get_vm_area reveals that
>(intentionally?) it does NOT insist there be a cushion page behind a VMA
>that is placed in front of a previously-allocated VMA, it ONLY

Could you explain me better? I agree that there's no good reason trying to
free the gap-faulting page, but I don't see how there couldn't be a
page-gap between two vmalloced areas.

Andrea Arcangeli