Subject: Re: [PATCH -next] mm: delete oversized WARN_ON() in kvmalloc() calls

From: Jeremy Sowden <[email-masked]>
Date: Thu, 2 Dec 2021 10:38:15 +0000

On 2021-12-01, at 20:29:05 -0800, Andrew Morton wrote:
> On Thu, 2 Dec 2021 12:05:15 +0800 Bixuan Cui wrote:
> > 在 2021/12/2 上午11:26, Andrew Morton 写道:
> > >> Delete the WARN_ON() and return NULL directly for oversized
> > >> parameter in kvmalloc() calls.
> > >> Also add unlikely().
> > >>
> > >> Fixes: 7661809d493b ("mm: don't allow oversized kvmalloc() calls")
> > >> Signed-off-by: Bixuan Cui<[email-masked]>
> > >> ---
> > >> There are a lot of oversize warnings and patches about kvmalloc()
> > >> calls recently. Maybe these warnings are not very necessary.
> > >
> > > Or maybe they are.  Please let's take a look at these warnings,
> > > one at a time.  If a large number of them are bogus then sure,
> > > let's disable the runtime test.  But perhaps it's the case that
> > > calling code has genuine issues and should be repaired.
> >
> > Such as：
>
> Thanks, that's helpful.
>
> Let's bring all these to the attention of the relevant developers.
>
> If the consensus is "the code's fine, the warning is bogus" then let's
> consider retiring the warning.
>
> If the consensus is otherwise then hopefully they will fix their stuff!
>
> > https://syzkaller.appspot.com/bug?id=24452f89446639c901ac07379ccc702808471e8e
>
> (cc [email-masked])
>
> > https://syzkaller.appspot.com/bug?id=f7c5a86e747f9b7ce333e7295875cd4ede2c7a0d
>
> (cc [email-masked], maintainers)
>
> > https://syzkaller.appspot.com/bug?id=8f306f3db150657a1f6bbe1927467084531602c7
>
> (cc [email-masked])
>
> > https://syzkaller.appspot.com/bug?id=6f30adb592d476978777a1125d1f680edfc23e00
>
> (cc [email-masked])

The netfilter bug has since been fixed:

  https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/log/?id=7bbc3d385bd813077acaf0e6fdb2a86a901f5382

> > https://syzkaller.appspot.com/bug?id=4c9ab8c7d0f8b551950db06559dc9cde4119ac83
>
> (bpf again).

J.