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Thu, 27 Aug 2026 16:55:13 -0700 (PDT) Received: from mac.lan ([136.55.173.105]) by smtp.gmail.com with ESMTPSA id 956f58d0204a3-66e4eb3dcdbsm55704d50.4.2026.08.27.16.55.12 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Thu, 27 Aug 2026 16:55:12 -0700 (PDT) From: "Cen Zhang (Microsoft)" To: edumazet@google.com, ncardwell@google.com, davem@davemloft.net, kuba@kernel.org, pabeni@redhat.com Cc: kuniyu@google.com, horms@kernel.org, matttbe@kernel.org, martineau@kernel.org, geliang@kernel.org, yhs@fb.com, kafai@fb.com, andriin@fb.com, ast@kernel.org, netdev@vger.kernel.org, mptcp@lists.linux.dev, bpf@vger.kernel.org, linux-kernel@vger.kernel.org, AutonomousCodeSecurity@microsoft.com, xmei5@asu.edu, tgopinath@linux.microsoft.com, kys@microsoft.com, blbllhy@gmail.com Subject: [PATCH net v3 0/2] tcp: fix use-after-free in do_tcp_getsockopt() Date: Thu, 27 Aug 2026 19:55:09 -0400 Message-ID: X-Mailer: git-send-email 2.55.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: "Cen Zhang (Microsoft Security FORGE Labs)" do_tcp_getsockopt() has two lockless reads of icsk_ca_ops. Since BPF struct_ops congestion control made icsk_ca_ops point to dynamically allocated memory, a concurrent setsockopt(TCP_CONGESTION) can replace the pointer and free the old object while either reader is using it. Patch 1 fixes the TCP_CONGESTION path by copying ca_ops->name to a stack buffer while holding rcu_read_lock(). It also uses READ_ONCE() for the lockless load and annotates the relevant icsk_ca_ops stores with WRITE_ONCE(). Patch 2 fixes the TCP_CC_INFO path by keeping the READ_ONCE() load, ca_ops->get_info lookup, and call inside an RCU read-side critical section. Changes since v2 [1]: - Fix the TCP_CONGESTION build failure by loading icsk_ca_ops inline. - Drop the unrelated WRITE_ONCE() conversion in mptcp_ca_reset(). - Add READ_ONCE() to dctcp_get_info()'s icsk_ca_ops comparison. Changes in v2 [2]: - Add READ_ONCE() to both lockless icsk_ca_ops loads. - Add WRITE_ONCE() to all six explicit icsk_ca_ops stores. - Include the data-race annotations in the UAF series as requested by Eric Dumazet [3]. [1] https://lore.kernel.org/all/20260826171344.4133-1-blbllhy@gmail.com/ [2] https://lore.kernel.org/all/20260821182449.79785-1-blbllhy@gmail.com/ [3] https://lore.kernel.org/all/CANn89iKr1ypEFeL+7te3xWoNaK5AFyYQmr+pDh2zSZAxfgNKjw@mail.gmail.com/ Cen Zhang (Microsoft Security FORGE Labs) (2): tcp: fix use-after-free in do_tcp_getsockopt(TCP_CONGESTION) tcp: fix use-after-free in do_tcp_getsockopt(TCP_CC_INFO) net/ipv4/tcp.c | 18 ++++++++++++++---- net/ipv4/tcp_cong.c | 4 ++-- net/ipv4/tcp_dctcp.c | 4 ++-- net/ipv4/tcp_minisocks.c | 2 +- net/ipv4/tcp_output.c | 2 +- 5 files changed, 20 insertions(+), 10 deletions(-) base-commit: a3dee9bb902ee4357fa02e49b415d7724ee0140a -- 2.43.0