linux-kernel - Re: [syzbot] WARNING in rcu

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Message-ID: <875yvmhgc5.ffs@tglx>
Date:   Mon, 30 Aug 2021 21:39:54 +0200
From:   Thomas Gleixner <tglx@...utronix.de>
To:     paulmck@...nel.org
Cc:     syzbot <syzbot+f2ceae48bb0c0ab08b9d@...kaller.appspotmail.com>,
        bp@...en8.de, dwmw@...zon.co.uk, hpa@...or.com,
        linux-kernel@...r.kernel.org, mingo@...hat.com,
        syzkaller-bugs@...glegroups.com, x86@...nel.org
Subject: Re: [syzbot] WARNING in rcu_core

On Mon, Aug 30 2021 at 10:06, Paul E. McKenney wrote:
> On Mon, Aug 30, 2021 at 12:51:39PM +0200, Thomas Gleixner wrote:
>
> This looks like a use-after-free in a structure that unions the rcu_head
> structure with something else.
>
> Would adding a mem_dump_obj() somewhere in the debug-object code be
> helpful?

At least for the case where the object is not available in the debug
objects tracking.

> (Or propagate a return value out, similar to that of
> debug_object_activate()?)

That might be useful for some callers as well.

Thanks,

        tglx