From: Pablo Neira Ayuso <pablo@netfilter.org>
To: Florian Westphal <fw@strlen.de>
Cc: netfilter-devel@vger.kernel.org, syzkaller-bugs@googlegroups.com,
syzbot+f31660cf279b0557160c@syzkaller.appspotmail.com
Subject: Re: [PATCH nf] netfilter: nf_tables: unlink table before deleting it
Date: Tue, 21 Sep 2021 03:47:32 +0200 [thread overview]
Message-ID: <YUk5tHTsPmkqHK6E@salvia> (raw)
In-Reply-To: <20210913124233.16520-1-fw@strlen.de>
On Mon, Sep 13, 2021 at 02:42:33PM +0200, Florian Westphal wrote:
> syzbot reports following UAF:
> BUG: KASAN: use-after-free in memcmp+0x18f/0x1c0 lib/string.c:955
> nla_strcmp+0xf2/0x130 lib/nlattr.c:836
> nft_table_lookup.part.0+0x1a2/0x460 net/netfilter/nf_tables_api.c:570
> nft_table_lookup net/netfilter/nf_tables_api.c:4064 [inline]
> nf_tables_getset+0x1b3/0x860 net/netfilter/nf_tables_api.c:4064
> nfnetlink_rcv_msg+0x659/0x13f0 net/netfilter/nfnetlink.c:285
> netlink_rcv_skb+0x153/0x420 net/netlink/af_netlink.c:2504
>
> Problem is that all get operations are lockless, so the commit_mutex
> held by nft_rcv_nl_event() isn't enough to stop a parallel GET request
> from doing read-accesses to the table object even after synchronize_rcu().
>
> To avoid this, unlink the table first and store the table objects in
> on-stack scratch space.
Applied, thanks.
prev parent reply other threads:[~2021-09-21 1:55 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-13 7:35 [syzbot] KASAN: use-after-free Read in nft_table_lookup (2) syzbot
2021-09-13 12:42 ` [PATCH nf] netfilter: nf_tables: unlink table before deleting it Florian Westphal
2021-09-21 1:47 ` Pablo Neira Ayuso [this message]
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