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Received: from sslproxy05.your-server.de ([78.46.172.2]) by www62.your-server.de with esmtpsa (TLS1.3) tls TLS_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1s0Snl-000K9y-Bo; Fri, 26 Apr 2024 23:08:13 +0200 Received: from [178.197.249.19] (helo=linux.home) by sslproxy05.your-server.de with esmtpsa (TLS1.3) tls TLS_AES_256_GCM_SHA384 (Exim 4.96) (envelope-from ) id 1s0Snk-000A6x-0v; Fri, 26 Apr 2024 23:08:12 +0200 Subject: Re: [PATCH net] udp: fix segmentation crash for GRO packet without fraglist To: =?UTF-8?B?TGVuYSBXYW5nICjnjovlqJwp?= , "maze@google.com" , "willemdebruijn.kernel@gmail.com" Cc: "linux-kernel@vger.kernel.org" , "bpf@vger.kernel.org" , "steffen.klassert@secunet.com" , "kuba@kernel.org" , =?UTF-8?B?U2hpbWluZyBDaGVuZyAo5oiQ6K+X5piOKQ==?= , "pabeni@redhat.com" , "edumazet@google.com" , "netdev@vger.kernel.org" , "matthias.bgg@gmail.com" , "davem@davemloft.net" , "yan@cloudflare.com" References: <20240415150103.23316-1-shiming.cheng@mediatek.com> <77068ef60212e71b270281b2ccd86c8c28ee6be3.camel@mediatek.com> <662027965bdb1_c8647294b3@willemb.c.googlers.com.notmuch> <11395231f8be21718f89981ffe3703da3f829742.camel@mediatek.com> <66227ce6c1898_116a9b294be@willemb.c.googlers.com.notmuch> <6622acdd22168_122c5b2945@willemb.c.googlers.com.notmuch> <9f097bcafc5bacead23c769df4c3f63a80dcbad5.camel@mediatek.com> <6627ff5432c3a_1759e929467@willemb.c.googlers.com.notmuch> <274c7e9837e5bbe468d19aba7718cc1cf0f9a6eb.camel@mediatek.com> <66291716bcaed_1a760729446@willemb.c.googlers.com.notmuch> <662a63aeee385_1de39b294fd@willemb.c.googlers.com.notmuch> <752468b66d2f5766ea16381a0c5d7b82ab77c5c4.camel@mediatek.com> From: Daniel Borkmann Message-ID: Date: Fri, 26 Apr 2024 23:08:11 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.2 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 In-Reply-To: <752468b66d2f5766ea16381a0c5d7b82ab77c5c4.camel@mediatek.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit X-Authenticated-Sender: daniel@iogearbox.net X-Virus-Scanned: Clear (ClamAV 0.103.10/27257/Fri Apr 26 10:25:03 2024) On 4/26/24 11:52 AM, Lena Wang (王娜) wrote: [...] >>> From 301da5c9d65652bac6091d4cd64b751b3338f8bb Mon Sep 17 00:00:00 >> 2001 >>> From: Shiming Cheng >>> Date: Wed, 24 Apr 2024 13:42:35 +0800 >>> Subject: [PATCH net] net: prevent BPF pulling SKB_GSO_FRAGLIST skb >>> >>> A SKB_GSO_FRAGLIST skb can't be pulled data >>> from its fraglist as it may result an invalid >>> segmentation or kernel exception. >>> >>> For such structured skb we limit the BPF pulling >>> data length smaller than skb_headlen() and return >>> error if exceeding. >>> >>> Fixes: 3a1296a38d0c ("net: Support GRO/GSO fraglist chaining.") >>> Signed-off-by: Shiming Cheng >>> Signed-off-by: Lena Wang >>> --- >>> net/core/filter.c | 5 +++++ >>> 1 file changed, 5 insertions(+) >>> >>> diff --git a/net/core/filter.c b/net/core/filter.c >>> index 8adf95765cdd..8ed4d5d87167 100644 >>> --- a/net/core/filter.c >>> +++ b/net/core/filter.c >>> @@ -1662,6 +1662,11 @@ static DEFINE_PER_CPU(struct bpf_scratchpad, >>> bpf_sp); >>> static inline int __bpf_try_make_writable(struct sk_buff *skb, >>> unsigned int write_len) >>> { >>> +if (skb_is_gso(skb) && >>> + (skb_shinfo(skb)->gso_type & SKB_GSO_FRAGLIST) && >>> + write_len > skb_headlen(skb)) { >>> +return -ENOMEM; >>> +} >>> return skb_ensure_writable(skb, write_len); Dumb question, but should this guard be more generically part of skb_ensure_writable() internals, presumably that would be inside pskb_may_pull_reason(), or only if we ever see more code instances similar to this? Thanks, Daniel