lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening PHC | |
Open Source and information security mailing list archives
| ||
|
Date: Mon, 21 Dec 2020 16:11:01 -0800 From: Linus Torvalds <torvalds@...ux-foundation.org> To: Yu Zhao <yuzhao@...gle.com> Cc: Peter Xu <peterx@...hat.com>, Nadav Amit <nadav.amit@...il.com>, Andrea Arcangeli <aarcange@...hat.com>, linux-mm <linux-mm@...ck.org>, lkml <linux-kernel@...r.kernel.org>, Pavel Emelyanov <xemul@...nvz.org>, Mike Kravetz <mike.kravetz@...cle.com>, Mike Rapoport <rppt@...ux.vnet.ibm.com>, stable <stable@...r.kernel.org>, Minchan Kim <minchan@...nel.org>, Andy Lutomirski <luto@...nel.org>, Will Deacon <will@...nel.org>, Peter Zijlstra <peterz@...radead.org> Subject: Re: [PATCH] mm/userfaultfd: fix memory corruption due to writeprotect On Mon, Dec 21, 2020 at 4:00 PM Yu Zhao <yuzhao@...gle.com> wrote: > > My first instinct is to be conservative and revert 09854ba94c6a ("mm: > do_wp_page() simplification") so people are less likely to come back > and complain about performance issues from holding mmap lock for > write when clearing pte_write. Well, the thing is, that simplificaiton was actually part of fixing a real regression wrt GUP. Reverting that would break a308c71bf1e6 ("mm/gup: Remove enfornced COW mechanism"). And that one was the (better) fix for commit 17839856fd58 that fixed a real security issue, but did it with a big hammer that then caused problems for uffd-wp (and some other loads). There's a bit more context in the merge message in commit b25d1dc9474e Merge branch 'simplify-do_wp_page'. So while that commit 09854ba94c6a on its own is "just" a simplification, it's actually part of a bigger series that fixes serious problems. Linus
Powered by blists - more mailing lists