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Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , linux-kernel@vger.kernel.org, Henry Martin Subject: [PATCH 3/3] rxrpc: recheck RXRPC_CALL_TX_NO_MORE after sleeping in rxrpc_send_data() Date: Sun, 23 Aug 2026 13:53:18 +0800 Message-ID: <20260823055318.371374-4-bsdhenrymartin@gmail.com> X-Mailer: git-send-email 2.43.7 In-Reply-To: <20260823055318.371374-1-bsdhenrymartin@gmail.com> References: <20260823055318.371374-1-bsdhenrymartin@gmail.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Commit ae4f89989479 ("rxrpc: Fix ability to add more data to a call once MSG_MORE deasserted") added the RXRPC_CALL_TX_NO_MORE flag and an entry check in rxrpc_send_data() to stop late sends on a finalized call. However, the check runs only once at function entry: when the transmit window is full, wait_for_space drops call->user_mutex and sleeps, during which another thread sharing the same user_call_ID can finalize the call (queue the LAST packet, setting TX_NO_MORE and clearing send_queue). Upon waking, the reload path only re-verifies the shutdown flag and call state - and a just-finalized call is still in RXRPC_CALL_CLIENT_SEND_REQUEST until its data is hard-acked - so the thread proceeds to rxrpc_alloc_txqueue() with send_queue == NULL but tx_queue != NULL, triggering: WARNING: net/rxrpc/sendmsg.c:297 at rxrpc_alloc_txqueue and returning a spurious -ENOMEM. The call state itself is entirely legal at that point; the WARN_ON's implied assumption that send_queue == NULL implies tx_queue == NULL simply does not hold after finalization. Re-check RXRPC_CALL_TX_NO_MORE in the reload path after reacquiring user_mutex, mirroring the entry check, and bail out with -EPROTO. Found by the autokbug dynamic kernel fuzzer at Tencent Yunding Lab. Fixes: ae4f89989479 ("rxrpc: Fix ability to add more data to a call once MSG_MORE deasserted") Signed-off-by: Henry Martin --- net/rxrpc/sendmsg.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/net/rxrpc/sendmsg.c b/net/rxrpc/sendmsg.c index ed2c9a51005ad..b39af552c6b46 100644 --- a/net/rxrpc/sendmsg.c +++ b/net/rxrpc/sendmsg.c @@ -358,6 +358,14 @@ static int rxrpc_send_data(struct rxrpc_sock *rx, if (txb) rxrpc_see_txbuf(txb, rxrpc_txbuf_see_send_more); + ret = -EPROTO; + if (test_bit(RXRPC_CALL_TX_NO_MORE, &call->flags)) { + trace_rxrpc_abort(call->debug_id, rxrpc_sendmsg_late_send, + call->cid, call->call_id, call->rx_consumed, + 0, -EPROTO); + goto maybe_error; + } + ret = -EPIPE; if (sk->sk_shutdown & SEND_SHUTDOWN) goto maybe_error; -- 2.43.0