linux-kernel - Re: [RFC PATCH] mm/highmem: VM_BUG_ON() if offset + len > PAGE

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: <2701286.BEx9A2HvPv@leap>
Date:   Mon, 25 Apr 2022 22:05:29 +0200
From:   "Fabio M. De Francesco" <fmdefrancesco@...il.com>
To:     Ira Weiny <ira.weiny@...el.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        "Matthew Wilcox (Oracle)" <willy@...radead.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Peter Collingbourne <pcc@...gle.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH] mm/highmem: VM_BUG_ON() if offset + len > PAGE_SIZE

On lunedì 25 aprile 2022 18:47:18 CEST Ira Weiny wrote:
> On Mon, Apr 25, 2022 at 03:47:38AM +0200, Fabio M. De Francesco wrote:
> > On domenica 24 aprile 2022 12:48:06 CEST Fabio M. De Francesco wrote:
> > > Call VM_BUG_ON() if offset + len > PAGE_SIZE.
> > > 
> > > This is an RFC patch because I'm not sure if we actually need to 
> > BUG_ON(),
> > 
> > Actually I considered VM_BUG_ON() for consistency with the other 
functions 
> > in highmem.h
> > 
> > What about VM_WARN_ON_ONCE() here and also in memset_page?
> 
> For consistency leave this as a VM_BUG_ON[1]
> 
> I've been down a similar path[2] and there was a long discussion about 
it.[3]
> 
> In the end we settled on VM_BUG_ON.[4]

Thanks for your reply and for providing so many helpful links :)

I just read the ones related to VM_BUG_ON() (I don't have time for 
flush_dcache_page() today). Since the consensus for these kinds of issues 
is in favor of using VM_BUG_ON(), that's OK for me.

I will send a "real" patch by tomorrow.

Again, thanks,

Fabio

> As to the addition of flush_dcache_page().  There was a discussion here.
> 
> https://lore.kernel.org/lkml/CAHk-=wiKac4t-fOP_3fAf7nETfFLhT3ShmRmBq2J96y6jAr56Q@mail.gmail.com/
> 
> Ira
> 
> [1] https://lore.kernel.org/lkml/20210209205249.GB2975576@iweiny-DESK2.sc.intel.com/
> 
> [2] https://lore.kernel.org/lkml/20201209022250.GP1563847@iweiny-DESK2.sc.intel.com/
> 
> [3] https://lore.kernel.org/lkml/20201208213255.GO1563847@iweiny-DESK2.sc.intel.com/
> 
> [4] https://lore.kernel.org/lkml/20210210174928.3156073-1-ira.weiny@intel.com/