From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from localhost.localdomain (unknown [147.136.157.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 6C468314A89; Tue, 25 Nov 2025 11:57:53 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=147.136.157.2 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764071875; cv=none; b=ZkhkBk3E9qMrqWyD/5esgHcPnQCAS+Zs6/vcyp5Io5s9x3dUc87Emn5UNNCV1K0ZirR3y8vJgRkeeTqgxcyy+Vdg5sLM4hA0sxYeVzU8mUyr2a0IenHND+Ey4pQUSLIaU76G5NtwZvW8RoLCQE0FUyohnvvVZofZ5ZMUFWoThWQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764071875; c=relaxed/simple; bh=h+0zY3hYZrpAB5Wqkh5NLThM1vTJvoHZwkygu2+9/5U=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=KpB+W8pfdd4KObgIgTlQdUUHgwKIRcDv48Ql/PmzL5AMJX9eb9eGnB9N9qz2tvXgvFxzFYWLqOd9iZLMNoLnGnquRIOf1K2BBVQf4QFD1eM03R9lT3hHg4rO7KOnGLqRboLPSM6amXiwRpoNFcFOsRyTNomyIBoPAuACXZx2rjM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.dev; spf=none smtp.mailfrom=localhost.localdomain; arc=none smtp.client-ip=147.136.157.2 Authentication-Results: smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=localhost.localdomain Received: by localhost.localdomain (Postfix, from userid 1007) id 65EBA8B2A0B; Tue, 25 Nov 2025 19:57:46 +0800 (+08) From: Jiayuan Chen To: bpf@vger.kernel.org Cc: Jiayuan Chen , John Fastabend , Jakub Sitnicki , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , Neal Cardwell , Kuniyuki Iwashima , David Ahern , Andrii Nakryiko , Eduard Zingerman , Alexei Starovoitov , Daniel Borkmann , Martin KaFai Lau , Song Liu , Yonghong Song , KP Singh , Stanislav Fomichev , Hao Luo , Jiri Olsa , Shuah Khan , Michal Luczaj , Stefano Garzarella , Cong Wang , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org Subject: [PATCH bpf-next v4 0/3] bpf: Fix FIONREAD and copied_seq issues Date: Tue, 25 Nov 2025 19:56:37 +0800 Message-ID: <20251125115709.249440-1-jiayuan.chen@linux.dev> 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 syzkaller reported a bug [1] where a socket using sockmap, after being unloaded, exposed incorrect copied_seq calculation. The selftest I provided can be used to reproduce the issue reported by syzkaller. TCP recvmsg seq # bug 2: copied E92C873, seq E68D125, rcvnxt E7CEB7C, fl 40 WARNING: CPU: 1 PID: 5997 at net/ipv4/tcp.c:2724 tcp_recvmsg_locked+0xb2f/0x2910 net/ipv4/tcp.c:2724 Call Trace: receive_fallback_to_copy net/ipv4/tcp.c:1968 [inline] tcp_zerocopy_receive+0x131a/0x2120 net/ipv4/tcp.c:2200 do_tcp_getsockopt+0xe28/0x26c0 net/ipv4/tcp.c:4713 tcp_getsockopt+0xdf/0x100 net/ipv4/tcp.c:4812 do_sock_getsockopt+0x34d/0x440 net/socket.c:2421 __sys_getsockopt+0x12f/0x260 net/socket.c:2450 __do_sys_getsockopt net/socket.c:2457 [inline] __se_sys_getsockopt net/socket.c:2454 [inline] __x64_sys_getsockopt+0xbd/0x160 net/socket.c:2454 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xcd/0xfa0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f A sockmap socket maintains its own receive queue (ingress_msg) which may contain data from either its own protocol stack or forwarded from other sockets. FD1:read() -- FD1->copied_seq++ | [read data] | [enqueue data] v [sockmap] -> ingress to self -> ingress_msg queue FD1 native stack ------> ^ -- FD1->rcv_nxt++ -> redirect to other | [enqueue data] | | | ingress to FD1 v ^ ... | [sockmap] FD2 native stack The issue occurs when reading from ingress_msg: we update tp->copied_seq by default, but if the data comes from other sockets (not the socket's own protocol stack), tcp->rcv_nxt remains unchanged. Later, when converting back to a native socket, reads may fail as copied_seq could be significantly larger than rcv_nxt. Additionally, FIONREAD calculation based on copied_seq and rcv_nxt is insufficient for sockmap sockets, requiring separate field tracking. [1] https://syzkaller.appspot.com/bug?extid=06dbd397158ec0ea4983 --- v1 -> v4: Use skmsg.sk instead of extending BPF_F_XXX macro and fix CI failure reported by CI v1: https://lore.kernel.org/bpf/20251117110736.293040-1-jiayuan.chen@linux.dev/ Jiayuan Chen (3): bpf, sockmap: Fix incorrect copied_seq calculation bpf, sockmap: Fix FIONREAD for sockmap bpf, selftest: Add tests for FIONREAD and copied_seq include/linux/skmsg.h | 58 ++++- net/core/skmsg.c | 28 ++- net/ipv4/tcp_bpf.c | 26 ++- net/ipv4/udp_bpf.c | 25 ++- .../selftests/bpf/prog_tests/sockmap_basic.c | 203 +++++++++++++++++- .../bpf/progs/test_sockmap_pass_prog.c | 8 + 6 files changed, 331 insertions(+), 17 deletions(-) -- 2.43.0