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Thu, 25 Jan 2024 10:18:48 +0800 Message-ID: Date: Thu, 25 Jan 2024 10:18:48 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.9.0 Subject: Re: SECURITY PROBLEM: Any user can crash the kernel with TCP ZEROCOPY Content-Language: en-US To: Eric Dumazet CC: Matthew Wilcox , , , , , , , , , , References: <20240119092024.193066-1-zhangpeng362@huawei.com> <5106a58e-04da-372a-b836-9d3d0bd2507b@huawei.com> <4f78fea2-ced6-fc5a-c7f2-b33fcd226f06@huawei.com> From: "zhangpeng (AS)" In-Reply-To: Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [10.174.179.160] X-ClientProxiedBy: dggems703-chm.china.huawei.com (10.3.19.180) To kwepemm600020.china.huawei.com (7.193.23.147) X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: E406514000E X-Stat-Signature: 4bx57rkz1kuotnhx4fxfjxbk344eku64 X-Rspam-User: X-HE-Tag: 1706149134-146041 X-HE-Meta: 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 2024/1/24 18:11, Eric Dumazet wrote: > On Wed, Jan 24, 2024 at 10:30 AM zhangpeng (AS) wrote: >> >> By using git-bisect, the patch that introduces this issue is 05255b823a617 >> ("tcp: add TCP_ZEROCOPY_RECEIVE support for zerocopy receive."). v4.18-rc1. >> >> Currently, there are no other repro or c reproduction programs can reproduce >> the issue. The syz log used to reproduce the issue is as follows: >> >> r3 = socket$inet_tcp(0x2, 0x1, 0x0) >> mmap(&(0x7f0000ff9000/0x4000)=nil, 0x4000, 0x0, 0x12, r3, 0x0) >> r4 = socket$inet_tcp(0x2, 0x1, 0x0) >> bind$inet(r4, &(0x7f0000000000)={0x2, 0x4e24, @multicast1}, 0x10) >> connect$inet(r4, &(0x7f00000006c0)={0x2, 0x4e24, @empty}, 0x10) >> r5 = openat$dir(0xffffffffffffff9c, &(0x7f00000000c0)='./file0\x00', >> 0x181e42, 0x0) >> fallocate(r5, 0x0, 0x0, 0x85b8818) >> sendfile(r4, r5, 0x0, 0x3000) >> getsockopt$inet_tcp_TCP_ZEROCOPY_RECEIVE(r4, 0x6, 0x23, >> &(0x7f00000001c0)={&(0x7f0000ffb000/0x3000)=nil, 0x3000, 0x0, 0x0, >> 0x0, 0x0, 0x0, 0x0, 0x0}, &(0x7f0000000440)=0x10) >> r6 = openat$dir(0xffffffffffffff9c, &(0x7f00000000c0)='./file0\x00', >> 0x181e42, 0x0) >> > Could you try the following fix then ? > > (We also could remove the !skb_frag_off(frag) condition, as the > !PageCompound() is necessary it seems :/) > > Thanks a lot ! > > diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c > index 1baa484d21902d2492fc2830d960100dc09683bf..ee954ae7778a651a9da4de057e3bafe35a6e10d6 > 100644 > --- a/net/ipv4/tcp.c > +++ b/net/ipv4/tcp.c > @@ -1785,7 +1785,9 @@ static skb_frag_t *skb_advance_to_frag(struct > sk_buff *skb, u32 offset_skb, > > static bool can_map_frag(const skb_frag_t *frag) > { > - return skb_frag_size(frag) == PAGE_SIZE && !skb_frag_off(frag); > + return skb_frag_size(frag) == PAGE_SIZE && > + !skb_frag_off(frag) && > + !PageCompound(skb_frag_page(frag)); > } > > static int find_next_mappable_frag(const skb_frag_t *frag, This patch doesn't fix this issue. The page cache that can trigger this issue doesn't necessarily need to be compound. 🙁 -- Best Regards, Peng