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([147.46.174.222]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-37c521cac5bsm8997512a91.5.2026.06.18.03.27.25 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 18 Jun 2026 03:27:28 -0700 (PDT) From: Sechang Lim To: John Fastabend , Jakub Sitnicki , Eric Dumazet , Kuniyuki Iwashima , Paolo Abeni , Willem de Bruijn , "David S . Miller" , Jakub Kicinski Cc: Simon Horman , Bobby Eshleman , Jiayuan Chen , netdev@vger.kernel.org, bpf@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH bpf v3 0/2] bpf, sockmap: reject a packet-modifying SK_SKB stream parser Date: Thu, 18 Jun 2026 10:27:06 +0000 Message-ID: <20260618102718.2331468-1-rhkrqnwk98@gmail.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit A BPF_PROG_TYPE_SK_SKB stream parser runs on strparser's message head, which can chain skbs through frag_list. A parser that resizes the skb frees the frag_list segments that strparser still tracks through skb_nextp, leading to a use-after-free. A stream parser is only meant to measure the next message, not to modify the packet, so reject a packet-modifying parser at attach time rather than working around the resize at runtime. v3: - reject the parser at attach time instead of cloning the skb at runtime (Kuniyuki Iwashima, Jiayuan Chen) - add a selftest (Bobby Eshleman) v2: - https://lore.kernel.org/all/20260612123553.2724240-1-rhkrqnwk98@gmail.com/ v1: - https://lore.kernel.org/all/20260609112316.3685738-1-rhkrqnwk98@gmail.com/ Sechang Lim (2): bpf, sockmap: fix use-after-free when the stream parser resizes the skb selftests/bpf: test rejection of a packet-modifying SK_SKB stream parser net/core/sock_map.c | 20 ++++++++++++ .../selftests/bpf/prog_tests/sockmap_strp.c | 31 +++++++++++++++++++ .../selftests/bpf/progs/test_sockmap_strp.c | 7 +++++ 3 files changed, 58 insertions(+) -- 2.43.0