linux-hardening - Re: [PATCH] fs: Use CHECK_DATA_CORRUPTION() when kernel bugs are detected

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Date:   Fri, 27 Jan 2023 10:38:19 -0800
From:   Kees Cook <keescook@...omium.org>
To:     Christian Brauner <brauner@...nel.org>
Cc:     Jann Horn <jannh@...gle.com>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-hardening@...r.kernel.org,
        kernel-hardening@...ts.openwall.com
Subject: Re: [PATCH] fs: Use CHECK_DATA_CORRUPTION() when kernel bugs are
 detected

On Fri, Jan 27, 2023 at 11:58:15AM +0100, Christian Brauner wrote:
> On Thu, Jan 26, 2023 at 08:35:49AM -0800, Kees Cook wrote:
> > On Mon, Jan 16, 2023 at 08:14:25PM +0100, Jann Horn wrote:
> > > Currently, filp_close() and generic_shutdown_super() use printk() to log
> > > messages when bugs are detected. This is problematic because infrastructure
> > > like syzkaller has no idea that this message indicates a bug.
> > > In addition, some people explicitly want their kernels to BUG() when kernel
> > > data corruption has been detected (CONFIG_BUG_ON_DATA_CORRUPTION).
> > > And finally, when generic_shutdown_super() detects remaining inodes on a
> > > system without CONFIG_BUG_ON_DATA_CORRUPTION, it would be nice if later
> > > accesses to a busy inode would at least crash somewhat cleanly rather than
> > > walking through freed memory.
> > > 
> > > To address all three, use CHECK_DATA_CORRUPTION() when kernel bugs are
> > > detected.
> > 
> > Seems reasonable to me. I'll carry this unless someone else speaks up.
> 
> I've already picked this into a branch with other fs changes for coming cycle.

Okay, great! I'll drop it from my tree.

Reviewed-by: Kees Cook <keescook@...omium.org>

-- 
Kees Cook