From: Pablo Neira Ayuso <pablo@netfilter.org>
To: Taehee Yoo <ap420073@gmail.com>
Cc: fw@strlen.de, netfilter-devel@vger.kernel.org
Subject: Re: [PATCH V3] netfilter: x_tables: Fix use-after-free in ipt_do_table.
Date: Mon, 31 Jul 2017 20:24:28 +0200 [thread overview]
Message-ID: <20170731182428.GA24605@salvia> (raw)
In-Reply-To: <20170727022204.17843-1-ap420073@gmail.com>
On Thu, Jul 27, 2017 at 11:22:04AM +0900, Taehee Yoo wrote:
> If verdict is NF_STOLEN in the SYNPROXY target,
> the skb is consumed.
> However, ipt_do_table() always tries to get ip header from the skb.
> So that, KASAN triggers the use-after-free message.
>
> We can reproduce this message using below command.
> # iptables -I INPUT -p tcp -j SYNPROXY --mss 1460
>
> [ 193.542265] BUG: KASAN: use-after-free in ipt_do_table+0x1405/0x1c10
> [ ... ]
> [ 193.578603] Call Trace:
> [ 193.581590] <IRQ>
> [ 193.584107] dump_stack+0x68/0xa0
> [ 193.588168] print_address_description+0x78/0x290
> [ 193.593828] ? ipt_do_table+0x1405/0x1c10
> [ 193.598690] kasan_report+0x230/0x340
> [ 193.603194] __asan_report_load2_noabort+0x19/0x20
> [ 193.608950] ipt_do_table+0x1405/0x1c10
> [ 193.613591] ? rcu_read_lock_held+0xae/0xd0
> [ 193.618631] ? ip_route_input_rcu+0x27d7/0x4270
> [ 193.624348] ? ipt_do_table+0xb68/0x1c10
> [ 193.629124] ? do_add_counters+0x620/0x620
> [ 193.634234] ? iptable_filter_net_init+0x60/0x60
> [ ... ]
>
> After this patch, only when verdict is XT_CONTINUE,
> ipt_do_table() tries to get ip header.
> Also arpt_do_table() is modified because it has same bug.
Applied, thanks.
prev parent reply other threads:[~2017-07-31 18:24 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-07-27 2:22 [PATCH V3] netfilter: x_tables: Fix use-after-free in ipt_do_table Taehee Yoo
2017-07-31 18:24 ` Pablo Neira Ayuso [this message]
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