linux-kernel - Re: PROBLEM: fanotify

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Date:   Thu, 26 Nov 2020 11:48:56 +0100
From:   Jan Kara <jack@...e.cz>
To:     Naresh Kamboju <naresh.kamboju@...aro.org>
Cc:     Jan Kara <jack@...e.cz>, Borislav Petkov <bp@...en8.de>,
        Paweł Jasiak <pawel@...iak.xyz>,
        open list <linux-kernel@...r.kernel.org>,
        linux-fsdevel@...r.kernel.org, X86 ML <x86@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Brian Gerst <brgerst@...il.com>,
        Andy Lutomirski <luto@...nel.org>
Subject: Re: PROBLEM: fanotify_mark EFAULT on x86

On Thu 26-11-20 01:01:30, Naresh Kamboju wrote:
> On Tue, 24 Nov 2020 at 15:50, Jan Kara <jack@...e.cz> wrote:
> >
> > On Tue 24-11-20 09:45:07, Borislav Petkov wrote:
> > > On Mon, Nov 23, 2020 at 11:46:51PM +0100, Paweł Jasiak wrote:
> > > > On 23/11/20, Jan Kara wrote:
> > > > > OK, with a help of Boris Petkov I think I have a fix that looks correct
> > > > > (attach). Can you please try whether it works for you? Thanks!
> > > >
> <trim>
> >
> > Thanks for checking! I didn't realize I needed to change the ifdefs as well
> > (I missed that bit in 121b32a58a3a). So do I understand correctly that
> > whenever the kernel is 64-bit, 64-bit syscall args (e.g. defined as u64) are
> > passed just fine regardless of whether the userspace is 32-bit or not?
> >
> > Also how about other 32-bit archs? Because I now realized that
> > CONFIG_COMPAT as well as the COMPAT_SYSCALL_DEFINE6() is also utilized by
> > other 32-bit archs (I can see a reference to compat_sys_fanotify_mark e.g.
> > in sparc, powerpc, and other args). So I probably need to actually keep
> > that for other archs but do the modification only for x86, don't I?
> >
> > So something like attached patch?
> 
> I have tested the attached patch on i386 and qemu_i386 and the reported problem
> got fixed.
> 
> Test links,
> https://lkft.validation.linaro.org/scheduler/job/1985236#L1176
> https://lkft.validation.linaro.org/scheduler/job/1985238#L801

Thanks for testing! I've added your tested-by tag.

								Honza

-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR