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=1793214629; b=qVswnA2mlY+y+EgfMIy1Ghkd4l0+ZMdpPAKXR3PFgBmEd6BfRpH4Y/RmJ5mAIEKWCoVw 81zlzWNlCA2TNN+esgf/cDRr92tUqy0Xyzz3Xyo/Ira8QOcmLEFUc158Azh87OaS+yIjp XnTuVqOauDiBRJD+BdiZGs7CfNwQt6iLW7eCtgALgcLw8NxJfkJ6+dNyy/6wE7dGS3u4f 8JNfY3JsIp9Mfa52+dG0fEBD5IsA9c0tAIxupeJYs9kb5OpJdlhgE/zeNgOKj5PBBjMX3 1Sgz9bEU8b/u0rXjLmpLjK6SAlGriu08ansYcGAZcKj1kis+18HXtkbmZ/DeQ/Ij9ZA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793214629; 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-Transfer-Encoding; bh=RwIHcvbqyBxF69og3/LxUq3xKSkw/sK9S1hrCPvruKs=; b=rOHDm1oRITPdz0AOg74AWlOTT7Yo2U9yD0+RXAWk/XSoN6hig8KIhr1nXpkFP60zjUjx 9O5U4DGQo2ACDckebB6yPskBxEUmgPkX8vkz3GzmD6J1LwG120ovZSTZnBKLi61QDBmuH lLlP4sUvAUQWKiesckQuB37Uky2XxQVRt2iawu/DaDp4TNk4ao978Ph0c6CZC2SCYXyt9 WM2GCPmQV/NE9F8XM0cIBMqfnrFJO1pRlVyb09yKjnGsA/osHs3AfmwodA40k2FHZzHM0 Z7GjL1HL/Xm3uY2pSF1Rio8kS1tZLsX456iGYCEK93i+3gz/HYuOp9t0NvKV3p7JMjg== 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=mJIhZoX7; 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 990A4606AB21; Wed, 28 Oct 2026 19:10:29 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=mJIhZoX7 Received: by smtp.kernel.org (Postfix) with ESMTPSA id EF0B11F01825; Wed, 28 Oct 2026 19:10:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1793214629; bh=RwIHcvbqyBxF69og3/LxUq3xKSkw/sK9S1hrCPvruKs=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=mJIhZoX7sVK2/mA7mW5uxXOc2S0U6LyOqcOrSSYLVKwKBY2qXL4rdxBU43ooVfYPP zQWkeNFPdBr+y3SE+m9xheTqxdZAVRQxH5Tf/RQl0KiWhybtyWeCGmexpl+HHRQJwo rjE1mC+K4XuaYWTEkPPIDWLJrNXefA+eB0RJ9Ajo= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, syzbot+6182afad5045e6703b3d@syzkaller.appspotmail.com, David Howells , Marc Dionne , Simon Horman , linux-afs@lists.infradead.org, stable@kernel.org, Jakub Kicinski , Sasha Levin Subject: [PATCH 6.1 0926/1887] rxrpc: Fix data-race warning and potential load/store tearing Date: Wed, 28 Oct 2026 17:50:22 +0100 Message-ID: <20261028170520.488736142@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261028170459.200466217@linuxfoundation.org> References: <20261028170459.200466217@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore X-Mailing-List: patches@lists.linux.dev List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: David Howells [ Upstream commit 5d5fe8bcd331f1e34e0943ec7c18432edfcf0e8b ] Fix the following: BUG: KCSAN: data-race in rxrpc_peer_keepalive_worker / rxrpc_send_data_packet which is reporting an issue with the reads and writes to ->last_tx_at in: conn->peer->last_tx_at = ktime_get_seconds(); and: keepalive_at = peer->last_tx_at + RXRPC_KEEPALIVE_TIME; The lockless accesses to these to values aren't actually a problem as the read only needs an approximate time of last transmission for the purposes of deciding whether or not the transmission of a keepalive packet is warranted yet. Also, as ->last_tx_at is a 64-bit value, tearing can occur on a 32-bit arch. Fix both of these by switching to an unsigned int for ->last_tx_at and only storing the LSW of the time64_t. It can then be reconstructed at need provided no more than 68 years has elapsed since the last transmission. Fixes: ace45bec6d77 ("rxrpc: Fix firewall route keepalive") Reported-by: syzbot+6182afad5045e6703b3d@syzkaller.appspotmail.com Closes: https://lore.kernel.org/r/695e7cfb.050a0220.1c677c.036b.GAE@google.com/ Signed-off-by: David Howells cc: Marc Dionne cc: Simon Horman cc: linux-afs@lists.infradead.org cc: stable@kernel.org Link: https://patch.msgid.link/1107124.1768903985@warthog.procyon.org.uk Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- net/rxrpc/ar-internal.h | 9 ++++++++- net/rxrpc/conn_event.c | 4 ++-- net/rxrpc/output.c | 10 +++++----- net/rxrpc/peer_event.c | 17 ++++++++++++++++- net/rxrpc/proc.c | 4 ++-- net/rxrpc/rxkad.c | 4 ++-- 6 files changed, 35 insertions(+), 13 deletions(-) diff --git a/net/rxrpc/ar-internal.h b/net/rxrpc/ar-internal.h index 8499ceb7719c8..fbec55c7e6dc5 100644 --- a/net/rxrpc/ar-internal.h +++ b/net/rxrpc/ar-internal.h @@ -303,7 +303,7 @@ struct rxrpc_peer { struct hlist_head error_targets; /* targets for net error distribution */ struct rb_root service_conns; /* Service connections */ struct list_head keepalive_link; /* Link in net->peer_keepalive[] */ - time64_t last_tx_at; /* Last time packet sent here */ + unsigned int last_tx_at; /* Last time packet sent here (time64_t LSW) */ seqlock_t service_conn_lock; spinlock_t lock; /* access lock */ unsigned int if_mtu; /* interface MTU for this peer */ @@ -986,6 +986,13 @@ void rxrpc_encap_err_rcv(struct sock *sk, struct sk_buff *skb, unsigned int udp_ void rxrpc_error_report(struct sock *); void rxrpc_peer_keepalive_worker(struct work_struct *); +/* Update the last transmission time on a peer for keepalive purposes. */ +static inline void rxrpc_peer_mark_tx(struct rxrpc_peer *peer) +{ + /* To avoid tearing on 32-bit systems, we only keep the LSW. */ + WRITE_ONCE(peer->last_tx_at, ktime_get_seconds()); +} + /* * peer_object.c */ diff --git a/net/rxrpc/conn_event.c b/net/rxrpc/conn_event.c index 293922df2a891..8079094844c0e 100644 --- a/net/rxrpc/conn_event.c +++ b/net/rxrpc/conn_event.c @@ -142,7 +142,7 @@ static void rxrpc_conn_retransmit_call(struct rxrpc_connection *conn, } ret = kernel_sendmsg(conn->params.local->socket, &msg, iov, ioc, len); - conn->params.peer->last_tx_at = ktime_get_seconds(); + rxrpc_peer_mark_tx(conn->params.peer); if (ret < 0) trace_rxrpc_tx_fail(chan->call_debug_id, serial, ret, rxrpc_tx_point_call_final_resend); @@ -262,7 +262,7 @@ static int rxrpc_abort_connection(struct rxrpc_connection *conn, trace_rxrpc_tx_packet(conn->debug_id, &whdr, rxrpc_tx_point_conn_abort); - conn->params.peer->last_tx_at = ktime_get_seconds(); + rxrpc_peer_mark_tx(conn->params.peer); _leave(" = 0"); return 0; diff --git a/net/rxrpc/output.c b/net/rxrpc/output.c index 3d9032fae9d91..6fb0c67ef8bb4 100644 --- a/net/rxrpc/output.c +++ b/net/rxrpc/output.c @@ -254,7 +254,7 @@ int rxrpc_send_ack_packet(struct rxrpc_call *call, bool ping, rtt_slot = rxrpc_begin_rtt_probe(call, serial, rxrpc_rtt_tx_ping); ret = kernel_sendmsg(conn->params.local->socket, &msg, iov, 2, len); - conn->params.peer->last_tx_at = ktime_get_seconds(); + rxrpc_peer_mark_tx(conn->params.peer); if (ret < 0) trace_rxrpc_tx_fail(call->debug_id, serial, ret, rxrpc_tx_point_call_ack); @@ -333,7 +333,7 @@ int rxrpc_send_abort_packet(struct rxrpc_call *call) ret = kernel_sendmsg(conn->params.local->socket, &msg, iov, 1, sizeof(pkt)); - conn->params.peer->last_tx_at = ktime_get_seconds(); + rxrpc_peer_mark_tx(conn->params.peer); if (ret < 0) trace_rxrpc_tx_fail(call->debug_id, serial, ret, rxrpc_tx_point_call_abort); @@ -449,7 +449,7 @@ int rxrpc_send_data_packet(struct rxrpc_call *call, struct sk_buff *skb, * message and update the peer record */ ret = kernel_sendmsg(conn->params.local->socket, &msg, iov, 2, len); - conn->params.peer->last_tx_at = ktime_get_seconds(); + rxrpc_peer_mark_tx(conn->params.peer); up_read(&conn->params.local->defrag_sem); if (ret < 0) { @@ -525,7 +525,7 @@ int rxrpc_send_data_packet(struct rxrpc_call *call, struct sk_buff *skb, IP_PMTUDISC_DONT); ret = kernel_sendmsg(conn->params.local->socket, &msg, iov, 2, len); - conn->params.peer->last_tx_at = ktime_get_seconds(); + rxrpc_peer_mark_tx(conn->params.peer); ip_sock_set_mtu_discover(conn->params.local->socket->sk, IP_PMTUDISC_DO); @@ -674,6 +674,6 @@ void rxrpc_send_keepalive(struct rxrpc_peer *peer) trace_rxrpc_tx_packet(peer->debug_id, &whdr, rxrpc_tx_point_version_keepalive); - peer->last_tx_at = ktime_get_seconds(); + rxrpc_peer_mark_tx(peer); _leave(""); } diff --git a/net/rxrpc/peer_event.c b/net/rxrpc/peer_event.c index 32561e9567fe3..77005c97dd904 100644 --- a/net/rxrpc/peer_event.c +++ b/net/rxrpc/peer_event.c @@ -515,6 +515,21 @@ static void rxrpc_distribute_error(struct rxrpc_peer *peer, int error, } } +/* + * Reconstruct the last transmission time. The difference calculated should be + * valid provided no more than ~68 years elapsed since the last transmission. + */ +static time64_t rxrpc_peer_get_tx_mark(const struct rxrpc_peer *peer, time64_t base) +{ + s32 last_tx_at = READ_ONCE(peer->last_tx_at); + s32 base_lsw = base; + s32 diff = last_tx_at - base_lsw; + + diff = clamp(diff, -RXRPC_KEEPALIVE_TIME, RXRPC_KEEPALIVE_TIME); + + return diff + base; +} + /* * Perform keep-alive pings. */ @@ -541,7 +556,7 @@ static void rxrpc_peer_keepalive_dispatch(struct rxrpc_net *rxnet, if (__rxrpc_use_local(peer->local)) { spin_unlock_bh(&rxnet->peer_hash_lock); - keepalive_at = peer->last_tx_at + RXRPC_KEEPALIVE_TIME; + keepalive_at = rxrpc_peer_get_tx_mark(peer, base) + RXRPC_KEEPALIVE_TIME; slot = keepalive_at - base; _debug("%02x peer %u t=%d {%pISp}", cursor, peer->debug_id, slot, &peer->srx.transport); diff --git a/net/rxrpc/proc.c b/net/rxrpc/proc.c index 47d36554ad311..ee07785860a01 100644 --- a/net/rxrpc/proc.c +++ b/net/rxrpc/proc.c @@ -234,13 +234,13 @@ static int rxrpc_peer_seq_show(struct seq_file *seq, void *v) now = ktime_get_seconds(); seq_printf(seq, "UDP %-47.47s %-47.47s %3u" - " %3u %5u %6llus %8u %8u\n", + " %3u %5u %6ds %8u %8u\n", lbuff, rbuff, refcount_read(&peer->ref), peer->cong_cwnd, peer->mtu, - now - peer->last_tx_at, + (s32)now - (s32)READ_ONCE(peer->last_tx_at), peer->srtt_us >> 3, jiffies_to_usecs(peer->rto_j)); diff --git a/net/rxrpc/rxkad.c b/net/rxrpc/rxkad.c index 84a61fa18bc06..038c4f2e8cef8 100644 --- a/net/rxrpc/rxkad.c +++ b/net/rxrpc/rxkad.c @@ -780,7 +780,7 @@ static int rxkad_issue_challenge(struct rxrpc_connection *conn) return -EAGAIN; } - conn->params.peer->last_tx_at = ktime_get_seconds(); + rxrpc_peer_mark_tx(conn->params.peer); trace_rxrpc_tx_packet(conn->debug_id, &whdr, rxrpc_tx_point_rxkad_challenge); _leave(" = 0"); @@ -838,7 +838,7 @@ static int rxkad_send_response(struct rxrpc_connection *conn, return -EAGAIN; } - conn->params.peer->last_tx_at = ktime_get_seconds(); + rxrpc_peer_mark_tx(conn->params.peer); _leave(" = 0"); return 0; } -- 2.53.0