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([147.46.174.222]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-8455382b886sm1380096b3a.51.2026.06.18.23.30.37 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 18 Jun 2026 23:30:42 -0700 (PDT) From: Sechang Lim To: Alexei Starovoitov , Andrii Nakryiko , Daniel Borkmann , Eduard Zingerman , Kumar Kartikeya Dwivedi , John Fastabend , Jakub Sitnicki , "David S . Miller" , Jakub Kicinski , Eric Dumazet , Paolo Abeni , Kuniyuki Iwashima , Willem de Bruijn , Shuah Khan Cc: Jiri Olsa , Martin KaFai Lau , Song Liu , Yonghong Song , Simon Horman , Bobby Eshleman , Jiayuan Chen , bpf@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org Subject: [PATCH bpf v4 0/3] bpf, sockmap: reject a packet-modifying SK_SKB stream parser Date: Fri, 19 Jun 2026 06:29:49 +0000 Message-ID: <20260619062959.3277612-1-rhkrqnwk98@gmail.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: netdev@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. v4: - drop the Fixes tag (Jiayuan Chen) - drop the unsafe skb modification from the test prog (John Fastabend) v3: - https://lore.kernel.org/all/20260618102718.2331468-1-rhkrqnwk98@gmail.com/ 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 (3): selftests/bpf: don't modify the skb in the strparser parser prog bpf, sockmap: reject a packet-modifying SK_SKB stream parser 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/sockmap_parse_prog.c | 22 ------------- .../selftests/bpf/progs/test_sockmap_strp.c | 7 +++++ 4 files changed, 58 insertions(+), 22 deletions(-) -- 2.43.0