From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793968613; b=Y0UELDvEK4zTf0lQqescMuNv8sl79nCPu3Jb80epRfOvnAoHWec393hoAnbSSTRlL/ws SKLL6+L/k0DOJSRKhqQIHuKGMwotEar5xv5wS/zjYPPcwMB91BkBMQZll+tSWafe3qXIp w82P0hQiGRGZcYoYhnQYxFq9S02iNiEO12ts8MWnsSxtbeuE/w9Qu+8xGWs4EkXkDmRlN 8aKNAgh/OP4p9WPErA75AVak1YtLtHLUJPCVNFC9oFq+CRjzVmjooJSCcpC4avffMUjCY VfUlbN1oeu2xOE14ZL1YBKVIvX0u0OGHN/+3ixptxm1rOJf+M87EJw0WqBvAWi4olJw== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793968613; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:Content-Type: Content-Transfer-Encoding; bh=TnLKaglbbXEAFvqSov0AzPE4Tl5hjAM8u+AUSR5bnbk=; b=MhvDFA8bl9IQQLuZbtBLTNxygzsindOLajLSAZ39STH+t59WwpqmdxxHtcdkeiVtcX93 ORcPdyOq20CORe4ecFUjVmLJHDqmCv0oiq0kZ4MZD+3UvWZVvKUvn3WHm13WhcDy9BCP+ 9rWOnHUipxZLTBDVMxR64Yt0Qgn/RGfpqEmO0VDcvM6BGl1fQDsG/jt0d+qz6t+J7n3Ov CV978/zFklW2loXj1+TmMMIjVUPsY0gHJiJiPirq6d0teYfX/pv4+0tzrrdeI0UlQVEYh vhCGSMLpdRN3ihnuRz0JTfACuim0R2Rgu8ciACYhd/xltqV57Gh+d23WQg+4b8wuqcQ== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=XKTJG4Mr; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id CCB25606A326 for ; Fri, 6 Nov 2026 12:36:52 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=XKTJG4Mr Received: by smtp.kernel.org (Postfix) with ESMTPSA id 985001F008A1; Fri, 6 Nov 2026 12:36:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793968612; bh=TnLKaglbbXEAFvqSov0AzPE4Tl5hjAM8u+AUSR5bnbk=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=XKTJG4Mre4RXAtngaJsIWfsYAO1gF4ocMPbb6Z1ImAvolYM5VFb60T0ItSST7THQS 2IgYFEhHe1EfNFb5UwpVXvUsTTrJLsJgob6UY6KRoEAya8I6AIpHfXGhZz1OrBJzU4 6YAzRHgEKQDjOz6LqQTsnlmpqIE6JoRihcSoETL230W+Q0DoK2BAz9kD/cbuUmQUnQ AX3pYztPmUkYC9UF8AXDFf77DbfksGoqg/PplypgwucrMpucsPqdsFeeD0fLlAewn9 wZqtvDpRkMoJxoc/gE7ogMKzdMluodb8BjhWHi5/Dw6pJ3tHaL8tuZK/TZpJIuXyia gXovNZh7Z5YSg== From: Sasha Levin To: stable@vger.kernel.org Cc: David Howells , Marc Dionne , Eric Dumazet , "David S. Miller" , Jakub Kicinski , Paolo Abeni , Simon Horman , linux-afs@lists.infradead.org, Sasha Levin Subject: [PATCH 6.12.y] rxrpc: Fix update of call->tx_pending without holding lock Date: Fri, 6 Nov 2026 07:36:50 -0500 Message-ID: <20261106123625.4013722-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <2026110437-felt-tip-think-1d33@gregkh> References: <2026110437-felt-tip-think-1d33@gregkh> X-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: David Howells [ Upstream commit 7801c42c3bb737cfb06194a383873fcad8daacf5 ] Currently, rxrpc_send_data() updates call->tx_pending just before it returns - but it won't be holding the call->user_mutex when it does this if a wait was interrupted by a signal. This would allow a parallel sendmsg() to race. Further, both the callers of rxrpc_send_data() call it with the lock held, and then it returns an indication through the parameter list to say whether it has dropped the lock or not - after which the callers both just drop the lock if it's still held. Fix this by: (1) Moving the release of call->user_mutex down into rxrpc_send_data() and get rid of the indicator parameter. This makes it easier to see where the lock is held. (2) After waiting, if the attempt to reacquire the mutex is interrupted, just return directly there rather than going to out_unlock (3) Restricting the txb variable to inside the buffering loop and leaving ->tx_pending set until we've queued the buffer. Note that there's a slight change in behaviour in that wait_for_space failure now doesn't check for completion because it doesn't hold the call user_mutex. The caller, however, should re-issue the send and pick up any error at a second attempt. Fixes: b0f571ecd794 ("rxrpc: Fix locking in rxrpc's sendmsg") Closes: https://sashiko.dev/#/patchset/20260702144919.172295-1-dhowells%40redhat.com Signed-off-by: David Howells cc: Marc Dionne cc: Eric Dumazet cc: "David S. Miller" cc: Jakub Kicinski cc: Paolo Abeni cc: Simon Horman cc: linux-afs@lists.infradead.org cc: stable@vger.kernel.org Link: https://patch.msgid.link/20261006133011.531806-4-dhowells@redhat.com Signed-off-by: Paolo Abeni [ sashal: adapted exit handling for code lacking RXRPC_CALL_TX_NO_MORE while preserving existing packet-length bookkeeping and the caller’s if/else structure ] Signed-off-by: Sasha Levin --- net/rxrpc/sendmsg.c | 59 +++++++++++++++++++++------------------------ 1 file changed, 27 insertions(+), 32 deletions(-) diff --git a/net/rxrpc/sendmsg.c b/net/rxrpc/sendmsg.c index c9b85848e825b..9d68e58dace9c 100644 --- a/net/rxrpc/sendmsg.c +++ b/net/rxrpc/sendmsg.c @@ -279,10 +279,9 @@ static void rxrpc_queue_packet(struct rxrpc_sock *rx, struct rxrpc_call *call, static int rxrpc_send_data(struct rxrpc_sock *rx, struct rxrpc_call *call, struct msghdr *msg, size_t len, - rxrpc_notify_end_tx_t notify_end_tx, - bool *_dropped_lock) + rxrpc_notify_end_tx_t notify_end_tx) + __releases(&call->user_mutex) { - struct rxrpc_txbuf *txb; struct sock *sk = &rx->sk; enum rxrpc_call_state state; long timeo; @@ -293,23 +292,18 @@ static int rxrpc_send_data(struct rxrpc_sock *rx, ret = rxrpc_wait_to_be_connected(call, &timeo); if (ret < 0) - return ret; + goto out_unlock; if (call->conn->state == RXRPC_CONN_CLIENT_UNSECURED) { ret = rxrpc_init_client_conn_security(call->conn); if (ret < 0) - return ret; + goto out_unlock; } /* this should be in poll */ sk_clear_bit(SOCKWQ_ASYNC_NOSPACE, sk); reload: - txb = call->tx_pending; - call->tx_pending = NULL; - if (txb) - rxrpc_see_txbuf(txb, rxrpc_txbuf_see_send_more); - ret = -EPIPE; if (sk->sk_shutdown & SEND_SHUTDOWN) goto maybe_error; @@ -337,6 +331,8 @@ static int rxrpc_send_data(struct rxrpc_sock *rx, } do { + struct rxrpc_txbuf *txb = call->tx_pending; + if (!txb) { size_t remain; @@ -355,6 +351,9 @@ static int rxrpc_send_data(struct rxrpc_sock *rx, ret = -ENOMEM; goto maybe_error; } + call->tx_pending = txb; + } else { + rxrpc_see_txbuf(txb, rxrpc_txbuf_see_send_more); } _debug("append"); @@ -392,12 +391,12 @@ static int rxrpc_send_data(struct rxrpc_sock *rx, ret = call->security->secure_packet(call, txb); if (ret < 0) - goto out; + goto out_unlock; txb->kvec[0].iov_len += txb->len; txb->len = txb->kvec[0].iov_len; rxrpc_queue_packet(rx, call, txb, notify_end_tx); - txb = NULL; + call->tx_pending = NULL; } } while (msg_data_left(msg) > 0); @@ -406,45 +405,46 @@ static int rxrpc_send_data(struct rxrpc_sock *rx, if (rxrpc_call_is_complete(call) && call->error < 0) ret = call->error; -out: - call->tx_pending = txb; +out_unlock: + mutex_unlock(&call->user_mutex); _leave(" = %d", ret); return ret; call_terminated: - rxrpc_put_txbuf(txb, rxrpc_txbuf_put_send_aborted); - _leave(" = %d", call->error); - return call->error; + ret = call->error; + goto out_unlock; maybe_error: if (copied) goto success; - goto out; + goto out_unlock; efault: ret = -EFAULT; - goto out; + goto out_unlock; wait_for_space: ret = -EAGAIN; if (msg->msg_flags & MSG_DONTWAIT) goto maybe_error; mutex_unlock(&call->user_mutex); - *_dropped_lock = true; + ret = rxrpc_wait_for_tx_window(rx, call, &timeo, msg->msg_flags & MSG_WAITALL); if (ret < 0) - goto maybe_error; + goto out_nolock; if (call->interruptibility == RXRPC_INTERRUPTIBLE) { if (mutex_lock_interruptible(&call->user_mutex) < 0) { ret = sock_intr_errno(timeo); - goto maybe_error; + goto out_nolock; } } else { mutex_lock(&call->user_mutex); } - *_dropped_lock = false; goto reload; +out_nolock: + _leave(" = %d [intr]", ret); + return copied ?: ret; } /* @@ -611,7 +611,6 @@ int rxrpc_do_sendmsg(struct rxrpc_sock *rx, struct msghdr *msg, size_t len) __releases(&rx->sk.sk_lock.slock) { struct rxrpc_call *call; - bool dropped_lock = false; int ret; struct rxrpc_send_params p = { @@ -717,12 +716,12 @@ int rxrpc_do_sendmsg(struct rxrpc_sock *rx, struct msghdr *msg, size_t len) } else if (p.command != RXRPC_CMD_SEND_DATA) { ret = -EINVAL; } else { - ret = rxrpc_send_data(rx, call, msg, len, NULL, &dropped_lock); + ret = rxrpc_send_data(rx, call, msg, len, NULL); + goto error_put; } out_put_unlock: - if (!dropped_lock) - mutex_unlock(&call->user_mutex); + mutex_unlock(&call->user_mutex); error_put: rxrpc_put_call(call, rxrpc_call_put_sendmsg); _leave(" = %d", ret); @@ -752,7 +751,6 @@ int rxrpc_kernel_send_data(struct socket *sock, struct rxrpc_call *call, struct msghdr *msg, size_t len, rxrpc_notify_end_tx_t notify_end_tx) { - bool dropped_lock = false; int ret; _enter("{%d},", call->debug_id); @@ -763,12 +761,9 @@ int rxrpc_kernel_send_data(struct socket *sock, struct rxrpc_call *call, mutex_lock(&call->user_mutex); ret = rxrpc_send_data(rxrpc_sk(sock->sk), call, msg, len, - notify_end_tx, &dropped_lock); + notify_end_tx); if (ret == -ESHUTDOWN) ret = call->error; - - if (!dropped_lock) - mutex_unlock(&call->user_mutex); _leave(" = %d", ret); return ret; } -- 2.53.0