linux-kernel - Re: [syzbot] [mm?] kernel BUG in sg_init

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: <CAJD7tkYA0ZjdjXAx3ZcFtFzAAbZ2+57QLh99o3JVBVSWNtZM7A@mail.gmail.com>
Date: Wed, 12 Feb 2025 09:20:24 -0800
From: Yosry Ahmed <yosryahmed@...gle.com>
To: Barry Song <21cnbao@...il.com>
Cc: syzbot <syzbot+adbc983a1588b7805de3@...kaller.appspotmail.com>, 
	ira.weiny@...el.com, akpm@...ux-foundation.org, chengming.zhou@...ux.dev, 
	hannes@...xchg.org, linux-kernel@...r.kernel.org, linux-mm@...ck.org, 
	nphamcs@...il.com, syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [mm?] kernel BUG in sg_init_one

On Mon, Mar 18, 2024 at 2:03 PM Barry Song <21cnbao@...il.com> wrote:
>
> On Tue, Mar 19, 2024 at 9:52 AM syzbot
> <syzbot+adbc983a1588b7805de3@...kaller.appspotmail.com> wrote:
> >
> > Hello,
> >
> > syzbot has tested the proposed patch but the reproducer is still triggering an issue:
> > WARNING in __kmap_to_page
> >
> > ------------[ cut here ]------------
> > WARNING: CPU: 0 PID: 3529 at mm/highmem.c:167 __kmap_to_page+0x100/0x194 mm/highmem.c:167
> > Modules linked in:
>
> + Ira
>
> Hi Ira,
>
> I noticed this warning is coming from commit ef6e06b2ef87077.
>
> you have a commit message like
> "    Because it is intended to remove kmap_to_page() add a warn on once to
>     the kmap checks to flag potential issues early.
> "
>
> Do we have a replacement for kmap_to_page()? The background is that we
> want to pass a highmem buffer to sg_set_page() but we only know its virt
> address.

I am reviving this thread because new zsmalloc changes will make
mappings sleepable, which will allow zswap to drop the memcpy() in
zswap_decompress() -- except for the !virt_addr_valid() case. We can
get rid of that too if we can use kmap_tp_page() in the scatterlist
code.

Ira, could you please answer Barry's question above about
kmap_to_page()? It has been a year and kmap_to_page() is still around.

Thanks.