Date:   Thu, 2 Dec 2021 14:03:43 -0800
From:   Andrew Morton <akpm@linux-foundation.org>
To:     Kees Cook <keescook@chromium.org>
Cc:     Leon Romanovsky <leon@kernel.org>,
        Matthew Wilcox <willy@infradead.org>,
        Bixuan Cui <cuibixuan@linux.alibaba.com>, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org, torvalds@linux-foundation.org,
        w@1wt.eu
Subject: Re: [PATCH -next] mm: delete oversized WARN_ON() in kvmalloc()
 calls
Message-Id: <20211202140343.0fd5dbc41513b1c95661ff8f@linux-foundation.org>
In-Reply-To: <202112021320.87AB40A@keescook>
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On Thu, 2 Dec 2021 13:23:13 -0800 Kees Cook <keescook@chromium.org> wrote:

> > > I think we have two cases:
> > > 
> > > - limiting kvmalloc allocations to INT_MAX
> > > - issuing a WARN when that limit is exceeded
> > > 
> > > The argument for the having the WARN is "that amount should never be
> > > allocated so we want to find the pathological callers".
> > > 
> > > But if the actual issue is that >INT_MAX is _acceptable_, then we have
> > > to do away with the entire check, not just the WARN.
> > 
> > First we need to get rid from WARN_ON(), which is completely safe thing to do.
> > 
> > Removal of the check can be done in second step as it will require audit
> > of whole kvmalloc* path.
> 
> If those are legit sizes, I'm fine with dropping the WARN. (But I still
> think if they're legit sizes, we must also drop the INT_MAX limit.)

Can we suppress the WARN if the caller passed __GFP_NOWARN?