linux-kernel - Re: KASAN: use-after-free Read in mnt_warn_timestamp

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Message-ID: <20191017023735.GS26530@ZenIV.linux.org.uk>
Date:   Thu, 17 Oct 2019 03:37:35 +0100
From:   Al Viro <viro@...iv.linux.org.uk>
To:     syzbot <syzbot+76a43f2b4d34cfc53548@...kaller.appspotmail.com>,
        akpm@...l.org, deepa.kernel@...il.com, hch@...radead.org,
        jlayton@...nel.org, linux-fsdevel@...r.kernel.org,
        linux-kernel@...r.kernel.org, lkundrak@...sk,
        syzkaller-bugs@...glegroups.com, tklauser@...rscht.ch,
        trond.myklebust@....uio.no
Subject: Re: KASAN: use-after-free Read in mnt_warn_timestamp_expiry

On Wed, Oct 16, 2019 at 07:27:05PM -0700, Eric Biggers wrote:

> How about the following?
> 
> 	pr_warn("%s filesystem being %s at %s supports timestamps until %04ld (0x%llx)\n",
> 		sb->s_type->name,
> 		is_mounted(mnt) ? "remounted" : "mounted",
> 		mntpath,
> 		tm.tm_year+1900, (unsigned long long)sb->s_time_max);
> 
> I think more people would understand "remounted" than "reconfigured".  Also,
> is_mounted(mnt) seems like a better choice than mnt_has_parent(real_mount(mnt)).

Works for me(tm).  Care to fold that into your patch and resend?