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=1794585241; b=0g8gn57+3N8jTBfzPqEFXyuQDZrthViMdwc218yjMzjm8y4HNCcNzKBhSUcQu7cS71ez kk3W5IFOZ/5q5yf7Th4JaKOIBWwxKymdheWOJkAaOgvEARMjp/sPWr/pe7YmHxIDkpMzq WUgeolYU/EWim+DBkEAazglBooUOHPX11YUNeyY3H5fA+XjOuRS7hY+lYulRLHV4IfwWQ qorKBNM9bpznM3DrgSYILbV3SbW1T6WlGyh40k89/TASQkWBT5hlKMVPrwpG3HSIIKOnK DykzC2RYuJqlduN0Mr4iQiXC7B6PLnXvOuvMXYt/WEeg+56hi/bkJYT9UEcdk5ABzrw== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794585241; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:User-Agent:X-stable:X-Patchwork-Hint: MIME-Version:Content-Type:Content-Transfer-Encoding; bh=y3tnhY+eqB0KkqvF+9bTGdX5diQZk6KoJLeKdK6fWcM=; b=Cq8wn4pXKj4aRiNc45SsC/6yJFWGR0jiKjiI5dKNWzNCG0bP0jNREnR6BlmbyfPgPxga 8g18dh5pmgl0QIqltzSVsDcR2Nl5tf5cqoT/c5uZya0XUpX/psCRqE1UHYe7iNWkBPRWv kLrJwPAlBPSEZtMWdpWXJQdopTlraxIh7iyQ4xJH8QzpM+cYPQOgssR/rt8JOW0PmU7RH t7r3YT35QB06BV4Kd4V/S7t5H542I5wNzyJ++II07v9W+rlzDBqvmQ057gMeSe2VVhb67 nMj/Z2TjhdTRFOZXVmUv5973KWaOfOqu8ECyEgdSGXr8yWFnN7TwsXAgVi5rppFKVPg== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=0hOoJsTd; 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 DA112606A880; Fri, 13 Nov 2026 15:54:01 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=0hOoJsTd Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8BE8B1F000C4; Fri, 13 Nov 2026 15:54:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1794585241; bh=y3tnhY+eqB0KkqvF+9bTGdX5diQZk6KoJLeKdK6fWcM=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=0hOoJsTdIvgoSWCggYogrl3fshSun/OqRTrTdJuPB/6QMvG52yjvzXsmmicHM8mQ5 HL7HEr7zon0TBoendbJg2bA8+KB0stztmJlUTuRPts9DPrlFQyCmwPZfGlN/1vImO4 VwErIHdJp610SlOObk0MEMKU3hmcE4Zndni3B0LI= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, David Howells , Marc Dionne , Eric Dumazet , "David S. Miller" , Jakub Kicinski , Paolo Abeni , Simon Horman , linux-afs@lists.infradead.org, Sasha Levin Subject: [PATCH 6.12 002/670] rxrpc: Fix update of call->tx_pending without holding lock Date: Fri, 13 Nov 2026 10:42:46 -0500 Message-ID: <20261113153811.262565183@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261113153811.177190860@linuxfoundation.org> References: <20261113153811.177190860@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore 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 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ 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