From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A4E1F2F12AE; Thu, 25 Jun 2026 13:06:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782392796; cv=none; b=gG+fC+/7DGMhoVyPIVUHc+xPfOivy8dDnF+DwEwvoNOU2nqgitxZWTH+tCWKfR5HcrlUT72J+pukFqVCeDCsOB6QCQKgkkDocvpe8ARiqTRAbuMScUTQvoYh/SXkRq4eaxujj213pGa+JmV2HBcA3FZjtxN86DuEMLtfth0JhZU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782392796; c=relaxed/simple; bh=KqDqSGRxaqX1UTwyv7O2fx8HJlV/mxHP4rpCaXrS5kU=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=EYXmmq1LCWlPOH20hSK6ApUARzcTayNQCYhCaV7pCRt9ggOF8MoAlS6DmFG7aQ2oyu0OkN6dK6mnFu0nxQk83wDRIaA/XBehqV/4ETYw9L0Qf/FUk8ZyOurFVCOZi6LyH8wf6gSLjcCvE9kJMsn5y9JVO44GcyKawiE42a3g6qw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=Ot7kQKiP; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="Ot7kQKiP" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 637021F00A3D; Thu, 25 Jun 2026 13:06:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1782392793; bh=r/MSc/MgR6Gz9je6AR1jkZup2uosCcFgvF1rclDi/UI=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=Ot7kQKiPueDby6Yo2fAgcTAtkt/yvxLOpCfekgT+HL+Tv8dp8VdxFs376AIZbR/fZ +/7TxuN+rB3YByCj/qyndwn2cjPr2FTGN3ymkyQynXbxraub9EPw3g3Yw0tMNIB5he AP9ojdaoDCAuEcasjJIf7MxQPPWM0D5hQFnisPB8= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Xiang Mei , Weiming Shi , Jakub Kicinski Subject: [PATCH 6.18 11/60] net: qualcomm: rmnet: fix endpoint use-after-free in rmnet_dellink() Date: Thu, 25 Jun 2026 14:02:56 +0100 Message-ID: <20260625125647.153229904@linuxfoundation.org> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260625125645.554579168@linuxfoundation.org> References: <20260625125645.554579168@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Weiming Shi commit d00c953a8f69921f484b629801766da68f27f658 upstream. rmnet_dellink() removes the endpoint from the hash table with hlist_del_init_rcu() and then immediately frees it with kfree(). However, RCU readers on the receive path (rmnet_rx_handler -> __rmnet_map_ingress_handler) may still hold a reference to the endpoint and dereference ep->egress_dev after the memory has been freed. The endpoint is a kmalloc-32 object, and the stale read at offset 8 corresponds to the egress_dev pointer. BUG: unable to handle page fault for address: ffffffffde942eef Oops: 0002 [#1] SMP NOPTI CPU: 1 UID: 0 PID: 137 Comm: poc_write Not tainted 7.0.0+ #4 PREEMPTLAZY RIP: 0010:rmnet_vnd_rx_fixup (rmnet_vnd.c:27) Call Trace: __rmnet_map_ingress_handler (rmnet_handlers.c:48 rmnet_handlers.c:101) rmnet_rx_handler (rmnet_handlers.c:129 rmnet_handlers.c:235) __netif_receive_skb_core.constprop.0 (net/core/dev.c:6096) __netif_receive_skb_one_core (net/core/dev.c:6208) netif_receive_skb (net/core/dev.c:6467) tun_get_user (drivers/net/tun.c:1955) tun_chr_write_iter (drivers/net/tun.c:2003) vfs_write (fs/read_write.c:688) ksys_write (fs/read_write.c:740) Add an rcu_head field to struct rmnet_endpoint and replace kfree() with kfree_rcu() so the endpoint memory remains valid through the RCU grace period. Also remove the rmnet_vnd_dellink() call and inline only the nr_rmnet_devs decrement, since rmnet_vnd_dellink() would set ep->egress_dev to NULL during the grace period, creating a data race with lockless readers. Fixes: ceed73a2cf4a ("drivers: net: ethernet: qualcomm: rmnet: Initial implementation") Reported-by: Xiang Mei Signed-off-by: Weiming Shi Link: https://patch.msgid.link/20260514122511.3083479-2-bestswngs@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman --- drivers/net/ethernet/qualcomm/rmnet/rmnet_config.c | 8 ++++---- drivers/net/ethernet/qualcomm/rmnet/rmnet_config.h | 1 + 2 files changed, 5 insertions(+), 4 deletions(-) --- a/drivers/net/ethernet/qualcomm/rmnet/rmnet_config.c +++ b/drivers/net/ethernet/qualcomm/rmnet/rmnet_config.c @@ -213,8 +213,8 @@ static void rmnet_dellink(struct net_dev ep = rmnet_get_endpoint(real_port, mux_id); if (ep) { hlist_del_init_rcu(&ep->hlnode); - rmnet_vnd_dellink(mux_id, real_port, ep); - kfree(ep); + real_port->nr_rmnet_devs--; + kfree_rcu(ep, rcu); } netdev_upper_dev_unlink(real_dev, dev); @@ -238,9 +238,9 @@ static void rmnet_force_unassociate_devi hash_for_each_safe(port->muxed_ep, bkt_ep, tmp_ep, ep, hlnode) { unregister_netdevice_queue(ep->egress_dev, &list); netdev_upper_dev_unlink(real_dev, ep->egress_dev); - rmnet_vnd_dellink(ep->mux_id, port, ep); hlist_del_init_rcu(&ep->hlnode); - kfree(ep); + port->nr_rmnet_devs--; + kfree_rcu(ep, rcu); } rmnet_unregister_real_device(real_dev); unregister_netdevice_many(&list); --- a/drivers/net/ethernet/qualcomm/rmnet/rmnet_config.h +++ b/drivers/net/ethernet/qualcomm/rmnet/rmnet_config.h @@ -18,6 +18,7 @@ struct rmnet_endpoint { u8 mux_id; struct net_device *egress_dev; struct hlist_node hlnode; + struct rcu_head rcu; }; struct rmnet_egress_agg_params {