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Wed, 26 Aug 2026 10:14:09 -0700 (PDT) Received: from mac.lan ([136.55.173.105]) by smtp.gmail.com with ESMTPSA id 00721157ae682-8570d620433sm19313287b3.42.2026.08.26.10.14.08 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Wed, 26 Aug 2026 10:14:08 -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 v2 0/2] tcp: fix use-after-free in do_tcp_getsockopt() Date: Wed, 26 Aug 2026 13:13:42 -0400 Message-ID: <20260826171344.4133-1-blbllhy@gmail.com> X-Mailer: git-send-email 2.55.0 Precedence: bulk X-Mailing-List: bpf@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 every explicit icsk_ca_ops store 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 v1 [1]: - 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 [2]. [1] https://lore.kernel.org/all/20260821182449.79785-1-blbllhy@gmail.com/ [2] 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 | 2 +- net/ipv4/tcp_minisocks.c | 2 +- net/ipv4/tcp_output.c | 2 +- net/mptcp/protocol.c | 2 +- 6 files changed, 20 insertions(+), 10 deletions(-) base-commit: f967455fb2a5a2079b9eb5823e9ccf359174bf9f -- 2.55.0