From: David Miller <davem@davemloft.net>
To: eric.dumazet@gmail.com
Cc: netdev@vger.kernel.org
Subject: Re: [PATCH net] ipv4: fix NULL dereference in free_fib_info_rcu()
Date: Tue, 15 Aug 2017 17:14:24 -0700 (PDT) [thread overview]
Message-ID: <20170815.171424.754423204914655743.davem@davemloft.net> (raw)
In-Reply-To: <1502799977.4936.71.camel@edumazet-glaptop3.roam.corp.google.com>
From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Tue, 15 Aug 2017 05:26:17 -0700
> From: Eric Dumazet <edumazet@google.com>
>
> If fi->fib_metrics could not be allocated in fib_create_info()
> we attempt to dereference a NULL pointer in free_fib_info_rcu() :
>
> m = fi->fib_metrics;
> if (m != &dst_default_metrics && atomic_dec_and_test(&m->refcnt))
> kfree(m);
>
> Before my recent patch, we used to call kfree(NULL) and nothing wrong
> happened.
>
> Instead of using RCU to defer freeing while we are under memory stress,
> it seems better to take immediate action.
>
> This was reported by syzkaller team.
>
> Fixes: 3fb07daff8e9 ("ipv4: add reference counting to metrics")
> Signed-off-by: Eric Dumazet <edumazet@google.com>
> Reported-by: Dmitry Vyukov <dvyukov@google.com>
Applied and queued up for -stable.
prev parent reply other threads:[~2017-08-16 0:14 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-15 12:26 [PATCH net] ipv4: fix NULL dereference in free_fib_info_rcu() Eric Dumazet
2017-08-16 0:14 ` David Miller [this message]
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