linux-kernel - Re: [PATCH v5 3/4] kho: add support for preserving vmalloc allocations

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

Message-ID: <mafs0ikh7dg54.fsf@kernel.org>
Date: Wed, 24 Sep 2025 17:28:07 +0200
From: Pratyush Yadav <pratyush@...nel.org>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: Jason Gunthorpe <jgg@...dia.com>,  Mike Rapoport <rppt@...nel.org>,
  Alexander Graf <graf@...zon.com>,  Baoquan He <bhe@...hat.com>,
  Changyuan Lyu <changyuanl@...gle.com>,  Chris Li <chrisl@...nel.org>,
  Pasha Tatashin <pasha.tatashin@...een.com>,  Pratyush Yadav
 <pratyush@...nel.org>,  kexec@...ts.infradead.org,  linux-mm@...ck.org,
  linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 3/4] kho: add support for preserving vmalloc allocations

On Mon, Sep 22 2025, Andrew Morton wrote:

> On Mon, 22 Sep 2025 10:19:48 -0300 Jason Gunthorpe <jgg@...dia.com> wrote:
>
>> > +static void kho_vmalloc_free_chunks(struct kho_vmalloc *kho_vmalloc)
>> > +{
>> > +	struct kho_vmalloc_chunk *chunk = KHOSER_LOAD_PTR(kho_vmalloc->first);
>> > +
>> > +	while (chunk) {
>> > +		struct kho_vmalloc_chunk *tmp = chunk;
>> > +
>> > +		kho_vmalloc_unpreserve_chunk(chunk);
>> > +
>> > +		chunk = KHOSER_LOAD_PTR(chunk->hdr.next);
>> > +		kfree(tmp);
>> 
>> Shouldn't this be free_page()?
>
> Or vfree()?

It should be free_page(). The chunk isn't in the vmalloc-ed area, it is
the metadata to track it. It gets allocated in new_vmalloc_chunk() using
get_zeroed_page().

>
> Not sure why this code works - I'll suspend the series from linux-next
> for now.

It only gets called in the error path and that didn't get hit during
testing I suppose. Until v3 the chunk was being allocated using
kzalloc() so I guess this got missed in the move to get_zeroed_page().

I think Mike is out of office this week. Do you think this series is
stable enough to land in the upcoming merge window? If so, I can send a
v6 with the fix today.

-- 
Regards,
Pratyush Yadav