linux-kernel - Re: [BUG] x86/mm: regression after 4a02ed8e1cc3

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 linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <CAG48ez27-HYHoorKU00xByDa9mu1Vnuh4yjE3sr+6z6ATKnzSA@mail.gmail.com>
Date: Wed, 3 Sep 2025 16:42:37 +0200
From: Jann Horn <jannh@...gle.com>
To: Nadav Amit <nadav.amit@...il.com>
Cc: Giovanni Cabiddu <giovanni.cabiddu@...el.com>, Rik van Riel <riel@...riel.com>, 
	"the arch/x86 maintainers" <x86@...nel.org>, Linux Kernel Mailing List <linux-kernel@...r.kernel.org>, 
	Borislav Petkov <bp@...en8.de>, peterz@...radead.org, 
	Dave Hansen <dave.hansen@...ux.intel.com>, zhengqi.arch@...edance.com, 
	thomas.lendacky@....com, kernel-team@...a.com, 
	"open list:MEMORY MANAGEMENT" <linux-mm@...ck.org>, Andrew Morton <akpm@...ux-foundation.org>, jackmanb@...gle.com, 
	mhklinux@...look.com, andrew.cooper3@...rix.com, Manali.Shukla@....com, 
	Ingo Molnar <mingo@...nel.org>, Dave Hansen <dave.hansen@...el.com>, baolu.lu@...el.com, 
	david.guckian@...el.com, damian.muszynski@...el.com
Subject: Re: [BUG] x86/mm: regression after 4a02ed8e1cc3

On Wed, Sep 3, 2025 at 4:18 PM Nadav Amit <nadav.amit@...il.com> wrote:
> > On 2 Sep 2025, at 19:05, Jann Horn <jannh@...gle.com> wrote:
> > On x86, IOMMU flushes happen from arch_tlbbatch_add_pending() and
> > flush_tlb_mm_range(); the IOMMU folks might know better, but as far as
> > I know, there is nothing that elides IOMMU flushes depending on the
> > state of X86-internal flush generation tracking or such.
> >
> > To me this looks like a change that is correct but makes it easier to
> > hit IOMMU flushing issues in other places.
>
> This change is not correct. Do not reference info after calling
> put_flush_tlb_info().

To be clear, I worded that very confusingly, I meant that Rik's commit
4a02ed8e1cc3 looks correct to me.